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UU
THE
meOoCEE DINGS
OF THE
-LINNEAN SOCIETY
OF
Nise SOUTH WV ALDS
FOR THE YEAR
1941
VOL. LXVI.
WITH FOURTEEN PLATES. 206 Text-figures.
SYDNEY: PRINTED AND PUBLISHED FOR THE SOCIETY BY
AUSTRALASIAN MEDICAL PUBLISHING CO. LTD., Seamer Street, Glebe, Sydney,
and SOLD BY THE SOCIETY. 1941.
CONTENTS OF PROCEEDINGS, 1941.
PARTS I-II (Nos. 293-294). (Issued 15th May, 1941.)
Pages. Presidential Address, delivered at the Sixty-sixth Annual General Meeting, PATA Wieyesis BVA tone Whe, Jat, Isl, Jevolerson, IBYSYeVNEIP 55 gn 66 045. co ae i-xxiii OF ETCH X0) oe enn ee eer cine isis tc os Mote Meee aL cat tl lat! Mrchion In oleh alot XXiV Balance Sheets for the Year ending 28th February, 1941 .. .. .. .. .. XXV-XXVii Abstract of “Proceedings: © 22 0 2:2) Se ie eae ce a aera a ce mea XXViii Plant Ecology of the Bulli District. Part ii. Plant Communities of the Plateau and Scarp. By Consett Davis, M.Sc. (Plates i-ii and one Text-figure.) .. 1-19 Plant Ecology of the Bulli District. Part iii. Plant Communities of the Coastal Slopes and Plain. By Consett Davis, M.Sc. (Plates ijii-iv.) .. .. .. 20-32 A Summary of certain Aspects of the Scarab Problem, and a Contribution to a Bibliography of the Family Scarabaeidae. By D. Margaret Cumpston, M.Sc. BS A oe Bala a iabedt a LAIN 4 Se SiG ee re Sea yA er 33-40 Notes on Australian Diptera. xxxix. Family Chloropidae. Part iii. By John R. Malloch. (Communicated by Frank H. Taylor, F.R.E.S., F.Z.S.) (Thirteen Text-figures. ) Sli 38) CREE AE TNE). ROH ANESTH ee T ne a 41-64 Studies on Corticium rolfsii (Sace.) Curzi (Sclerotium rolfsii Sace.). i. Cultural Characters and Perfect Stage. ii. Mechanism of Parasitism. By F. L. Milthorpe, B.Sc.Agr. (Plate v and seven Text-figures.) Saray. 65-75
A Survey of the Mistletoe of New South Wales. By Valerie May, M.Sc. (Plate vi ‘and'fnineteen iMext-ficunes))) sees aii i a ee tn ey pe ee 77-87
CONTENTS.
PARTS III-IV (Nos. 295-296). (Issued 15th September, 1941.)
Nitrogen Fixation and Cellulose Decomposition by Soil Micro-organisms. ii. The Association between Azotobacter and Facultative-aerobic Cellulose- decomposers. By H. L. Jensen, Macleay Bacteriologist to the Society, and R. J. Swaby. (One Text-figure.) Scar MR ERS TUTTE EE oti een URE at Lae 1
Physiological Studies in Drought Resistance. i. Technique. By Eric Ashby and Valerie May. (Two Text-figures.) ide Vea 2
The Heology of the Central Coastal Area of New South Tiaites, iv. Forest Types on Soils from Hawkesbury Sandstone and Wianamatta Shale. By Ilma M. Pidgeon, M.Sc. Linnean Macleay Fellow of the Society in Botany. (Five Text-figures.) _ : ; hae AT CENT SO See aay Nae 2a
The Diptera of the Territory of NT @uineal Xli. Family Tipulidae. Part iv. By Charles P. Alexander. (Communicated by F. H. Taylor, F.R.E.S., F.Z.8.) (Hleven Text-figures. ) eA MarR Beh GL Sreh scence) Sir al aa wet Bn ael
Serological Studies of the Root- edna: Bactorer i. Strains of Rhizobium meliloti. By J. M. Vincent a
The Synonymy, Hosts, and Type Material ‘of Cunihenia i ouGEls Guninen) (Acarina: Trombidiidae). By Carl E. M. Gunther, M.D., B.S., D.T.M.
An Erythraeid Mite from New Guinea (Acarina: Hrythraeidae). By Carl BE. M. Gunther, M.D., B.S., D.T.M. (Four Text-figures.) se oe
Two New Trombidiid Larvae from New Guinea (Acarina: Terapia By Carl H. M. Gunther, M.D., B.S., D.T.M. (Five Text-figures.) .. c
Studies in Silurian Biachiopeda: i. Description of a New Genus and apecion: By Joan Johnston, B.Sc. (Plate vii and two Text-figures. ) SE
Notes on the Measurement of some Physical and Optical Properties of the New South Wales Torbanites. By J. A. Dulhunty, B.Sc., Linnean Macleay Fellow of the Society in Geology. (Four Text-figures.) .
Trichilogaster maideni (Froggatt) (Hymenopt., Gualeideides): a cwaen causing Galls on Acacia implezxa Benth., and A. Maideni F.v.M., with Observations on Australian Chalcidoid Galls. By N. S. Noble, D.Sc.Agr., M.Sc., D.I.C. (Plate viii and five Text-figures.) eS ui
An Illustrated Key to some Common Australian Gulieine ‘Mosquito. larvae ith Notes on the Morphology and Breeding Places. By A. R. Woodhill and G. Pasfield. (Hleven Text-figures.) Bee SP pie tre
Australian Hesperiidae. x. On Hesperilla Toniae Semicon! 1868. nee G. A. Waterhouse, D.Sc., B.H., F.R.E.S. POR en rec ees a) iy he Maer lay tas Lon ea aU
Notes on the Aphididae in Australia. i. Two Aphids new to New South Wales. (Hemiptera: Aphididae.) By H. H. Zeck. (Seventeen Text-figures. )
Miscellaneous Notes on Australian Diptera. viii. Subfamily Lomatiinae. By G. H. Hardy. (Four Text-figures.) : PAAR AA LORE PA Ei ASAE UE ED
Notes on Australian Lycaenidae. Part viii. On Ogyris zosine Hew., and O. genoveva Hew. By G. A. Waterhouse, D.Sc., B.E., F.R.E.S. .. :
Nitrogen Fixation and Cellulose Decomposition by Soil Micro-organisms. iii. Clostridium butyricum in association with Aerobic Cellulose-decomposers. By H. L. Jensen, Macleay Bacteriologist to the Society. (Two Text-figures. )
Some Nematode Parasites of Australian Birds. By T. Harvey Johnston and Patricia Mawson. (Twenty-two Text-figures.)
Notes on the Kamilaroi Stratigraphy in the Western Coalfiela of Naw South Wales. By J. A. Dulhunty, B.Sc., Linnean Macleay Fellow of the Society in Geology. (Plate ix and four Text-figures.)
lii
Pages.
89-106
107-112
113-137
138-144 145-154 155 156 157-159
160-168
169-177
178-200
201-214 215-218 219-222 223-233
234-238
239-249
250-256
257-267
iv CONTENTS.
PARTS V-VI (Nos. 297-298). (Issued 15th December, 1941.)
Pages. Australian Rust Studies. vi. Comparative Studies of Biotypes of Race 34 of Puccinia graminis Tritict. By W. L. Waterhouse and I. A. Watson, (Plate xi.) 269-275 Microbiological Investigations on the Dew-retting of Flax. By H. L. Jensen, Macleay Bacteriologist to the Society. (Plate x and two Text-figures.) 276-286 The Oviposition Responses of Three Species of Mosquitoes (Aédes (Stegomyia) aegypti Linnaeus, Culex (Culex) fatigans Wiedemann, Aédes (Pseudo- skusea) concolor Taylor), in relation to the Salinity of the Water. By A. R. Woodhill. (Two Text-figures.) 287-292 On Certain Debatable Questions in Cranioskeletal Homologies. By H. Leighton Kesteven, D.Sc., M.D. (Forty-four Text-figures.) 293-334 The Physical Effects of Heat on the Torbanites of New South Wales. By J. A. Dulhunty, B.Sc., Linnean Macleay Fellow of the Society in Geology. (Seven Text-figures. ) 335-348 On the Anatomy and Functional Adaptation of the Thorax and Pectoral Girdle in the Wallaroo (Macropus robustus). By W. Boardman. (Plate xii and nine Text-figures.) 349-387 On Australian Dermestidae. Part i. Descriptions of a New Genus and Two New Species; also a Note on the Genus Anthrenus. By J. W. T. Armstrong. (Three Text-figures.) 388-390 Studies in Trombidiidae (Acarina: Trombidiidae). By Carl E. M. Gunther, MIDs BS: Dive 391-395 The Development of Aédes (Pseudoskusea) concolor Taylor in relation to Small Quantities of Salts in Solution and to the Temperature of the Water. By A. R. Woodhill 396-400 Revision of Australian Lepidoptera. Oecophoridae. x. By A. Jefferis Turner, M.D., F.R.E.S. 401-424 The Relation of Temperature and Soil Moisture to the Development of Seedling Blight of Maize due to Gibberella fujikuroi and Gibberella fujikuroi var. subglutinans. By E. T. Edwards, Ph.D., M.Se.Agr. (Plates xiii—xiv.) 425-439 The Genus Pelecorhynchus (Diptera, Tabanoidea). By I. M. Mackerras, M.B., Ch.M., B.Sc., and the late Mary E. Fuller, B.Sc. (Title only.) XXxi (Part 1 of this paper, which was read in September, 1941, has been held over for publication with Part 2 as one paper in These ProcrEepines, Vol. Ixvii, Pts. 1-2, 1942.) Abstract ‘of “Proceedings, 4." 0) 055 Pee ee tee ecb are oem XXIX—-XXNii General Index fvty SLA). das Ae st) tat eee, Ae a eae Reena List of Plates .. XXXVi uist of New Genera: and. Species... C2 ose sS7 eee eee XXXV1iI-XXXViii Corrigendum XXXVI1li
ANNUAL GENERAL MEETING. WEDNESDAY, 26th Marcu, 1941.
The Sixty-sixth Annual General Meeting was held in the Society’s Rooms, Science House, Gloucester Street, Sydney, on Wednesday, 26th March, 1941.
Mr. R. H. Anderson, B.Se.Agr., President, in the Chair.
The minutes of the preceding Annual General Meeting (27th March, 1940) were read and confirmed.
PRESIDENTIAL ADDRESS.
The Sixty-sixth Annual General Meeting of this Society is being held at a time when the distractions of a world at war make it difficult to give due attention to ordinary activities. Nevertheless I have very much pleasure in recording for the Society a successful year in which its objects have been satisfactorily realized. We look forward with confidence to the coming year, being convinced in our minds that the knowledge we pursue has permanent worth in a world of changing values. Following the usual custom the first part of my address is devoted to a brief review of the Society’s activities during the past year.
It was with very great regret that your Council accepted the resignation of Dr. A. B. Walkom from the position of Secretary of the Society. Dr. Walkom resigned on the 81st October, 1940, in order to take up the position of Director of the Australian Museum. He offered, however, to act as Honorary Secretary until 3lst December, 1940, and this offer was gratefully accepted by your Council. Dr. Walkom has served our Society with distinction and efficiency since 1919, when he succeeded the late J. J. Fletcher as Secretary. He obtained the degree of B.Sc. at the University of Sydney in 1910, graduating with First Class Honours and the University Medal in Geology, and in 1918 was admitted to the degree of Doctor of Science, with Medal. He was Linnean Macleay Fellow of this Society in Geology for one year, resigning in 1913 to become Lecturer in Geology and Palaeontology at the University of Queensland, a position which he held until 1919, being President of the Royal Society of Queensland, 1918-19. While Secretary of the Society Dr. Walkom spent twelve months abroad as the holder of a Rockefeller Foundation Scholarship of the International Education Board. He was especially interested in the Mesozoic sediments of eastern Australia and is an out- standing authority on palaeobotany. Since 1926 he has been Honorary General Secretary of the Australian and New Zealand Association for the Advancement of Science, for several years Honorary Secretary of the Australian National Research Council, and also Editor-in-Chief of “Australian Science Abstracts”. He was also Chairman, Honorary Secretary and Honorary Treasurer of the Science House Management Committee for a number of years. As Secretary of our Society Dr. Walkom has carried out his duties with tact and efficiency and has earned the respect and liking of every member. We thank him for his services and wish him every happiness in his new position, knowing that he will fill it with every distinction.
Your Council selected Dr. N. S. Noble as successor to Dr. Walkom and appointed him to the position of Secretary from 2nd January, 1941. Dr. Noble was formerly an entomologist in the New South Wales Department of Agriculture. He graduated as Bachelor of Science in Agriculture with First Class Honours in 1928 and was appointed Assistant Entomologist in the Department of Agriculture. In 1929 he was awarded a Walter and Eliza Hall Agricultural Research Fellowship. With this he proceeded to the University of London, undertaking there graduate study and research in entomology;
A
ii PRESIDENTIAL ADDRESS.
he also worked at the Stored Products Research Laboratory, Bucks., and spent twelve months at the University of California, where he obtained the degree of M.Sc. In 1932 he was awarded the Diploma of the Imperial College of Science, University of London. In May, 1938, he was admitted to the degree of Doctor of Science in Agriculture for a thesis on “Australian Parasitic and Phytophagous Chalcidoidea”’. The results of Dr. Noble’s researches on a number of aspects of entomology have been published in thirty papers in various scientific journals. Dr. Noble has been the Business Manager of the Journal of the Australian Institute of Agricultural Science for the past four years.
Our Society has been singularly fortunate in the calibre of its past Secretaries, and I am quite certain that we have every reason to congratulate ourselves on our present choice. Your Council was thoroughly satisfied that Dr. Noble had the highest qualifi- cations and we hope he will be happy in the services of the Society.
Since the last Annual Meeting the names of eleven members have been added to the list, two members and one Corresponding member have been lost by death, the names of four have been removed on account of arrears of subscription, and three have resigned.
Herbert James Carter, who died suddenly in Sydney on 16th April, 1940, when within a few days of completion of his eighty-second year, was born at Marlborough, Wilts., England, on 28rd April, 1858. He was educated at Aldenham School and Cambridge University, where he was a scholar of Jesus College. He was a mathematics master at the Sydney Grammar School from 1881 to 1901 and was Principal of Ascham Girls’ School from then till 1914. He was President of this Society during 1925-26, and a member of Council from 1920 until 1939; also a Fellow of the Royal Hntomological Society of London. For many years he was honorary entomologist to the Australian Museum. He was science editor of the Australian Hncyclopaedia, published in 1926, and author of Gulliver in the Bush, in which he related many of his experiences in pursuit of his scientific work. He was especially interested in the Australian Coleoptera, particularly the families Tenebrionidae, Buprestidae, Cistelidae, and Dryopidae. In addition to descriptions of large numbers of new species, he paid particular attention , to matters of synonymy, and published a number of check-lists of the families, and revisions of the Australian species of various genera. He did not shirk the drudgery of the work on synonymy, but often deplored the practice of some European colleagues who, on what he considered inadequate evidence, described large numbers of Australian species as new, and so added to the difficulties of Australian coleopterists. His papers appear in a number of scientific journals from 1905 onwards, chiefly these ProcrrpInes, the Royal Zoological Society of New South Wales, and the Royal Society of South Australia. His last completed work, a short note on Dryopidae, was handed to Dr. Walkom only a few days before his death. His fine collection of Australian Coleoptera, including many types, has been given to the Division of Economic Entomology of the Council for Scientific and Industrial Research at Canberra. A charming personality, he left a host of friends in his scientific colleagues and in his former pupils, and our Society holds him in grateful and affectionate memory. §
August Goerling, who died at Pinjarra, Western Australia, in January, 1941, had been a member of the Society since 1936. He was a keen student of natural history and a friend of the late H. J. Carter. He had made extensive collections of insects, being more especially interested in the Coleoptera.
William Mountier Bale, a Corresponding member of the Society since 1888, died on 4th October, 1940, at Kew, Victoria, at the age of eighty-nine years. He was an authority on the Hydrozoa and was a Fellow of the Royal Microscopical Society.
In November, 1940, Mr. A. F. Basset Hull tendered his resignation as a Councillor. Mr. Hull had been a member of the Council for about twenty-five years and his resignation was accepted with very great regret, it being resolved that there be placed on record in the minutes an expression of appreciation of his services to the Society.
In November, 1940, a letter was received from the Under-Secretary, Chief Secretary’s Department, thanking the Council for suggestions in connection with the proposed amendment of the Birds and Animals Protection Act.
PRESIDENTIAL ADDRESS. iil
The proclamation protecting wild flowers and native piants was renewed for a further period of one year from Ist July, 1940, Casuarina Cunninghamiana (River Oak) having been added to the list of protected. plants.
We offer congratulations to Professor J. P. Hill, who, during 1940, was awarded the Darwin Medal of the Royal Society of London; also to Dr. R. J. Noble, who was appointed N.S.W. Under-Secretary for Agriculture, and to Dr. H. G. Raggatt, who was appointed Geological Adviser to the Commonwealth Government in 1940.
The plant house for the Macleay Bacteriologist, the erection of which was made possible through the generosity of the Commonwealth Bank of Australia, Rural Bank of New South Wales, Bank of New South Wales and Commercial Banking Company of Sydney, Limited, was completed early in 1940. Mr. R. J. Swaby, B.Sc.Agr., the Biochemist assisting the Macleay Bacteriologist, resigned on 19th October, 1940, and Mr. R. C. Betty, B.Se., who was selected to take his place, took up his duties on 1st February, 1941.
The year’s work of the Society’s research staff may be summarized thus:
Dr. H. L. Jensen, Macleay Bacteriologist to the Society, has carried out final experi- ments on the occurrence and distribution of free-living nitrogen-fixing bacteria in wheat soils and the results have been published in a paper written in collaboration with Mr. R. J. Swaby. This paper also includes experiments on the activity of anaerobic nitrogen- fixers (Clostridium) under soil conditions. The work on symbiosis between nitrogen- fixing and cellulose-decomposing organisms has been concluded. An introductory paper, dealing with the general aspects of the problem, was published in these ProcrEepINGS in December, 1940. A second paper, on the quantitative relationship between cellulose decomposition and nitrogen fixation under varying experimental conditions, has been submitted for publication in these ProckEpInes, and a third paper, dealing especially with anaerobic nitrogen-fixing bacteria, has been prepared. The results have shown consistently that nitrogen fixation on the basis of cellulosic materials, requires the co-operation of at least one partly or wholly anaerobic component in the association of organisms; this corroborates the results previously obtained in experiments with soils to which straw was added. A number of strains of root nodule bacteria from various clovers and medics have been studied. The bacteria from Trifolium spp. were found able to induce root nodule formation in plants at reactions far more acid than those from Medicago spp. No support has been found for the theory that molybdenum as a “trace element” stimulates nitrogen fixation in leguminous plants as it does in Azotobacter. Stimulation of plant growth by inoculation of the seed with Azotobacter, as claimed by many recent Russian investigators, has not been observed with certainty in leguminous pasture plants.
Miss Ilma Pidgeon, Linnean Macleay Fellow of the Society in Botany, has completed a paper on the ‘‘Ecology of the Central Coastal Area of New South Wales. iii’, dealing with forest types on Hawkesbury Sandstone and Wianamatta Shales, and this has been submitted for publication in the ProcrEpiInes. This paper embodies several new technical features, including an attempt to represent the climatic tolerance of many species of Eucalyptus. It also contains a development of the author’s views on the classification of vegetation. Miss Pidgeon has also prepared a report which has been submitted to the Council, and to the Council for Scientific and Industrial Research on the effects of different salts upon water loss from oranges. Experiments reveal that both uptake of water and water loss are affected by the hydrogen ion concentration of solutions in which the oranges are immersed, and that a desirable detergent should have a low pH value. The work has already provided information of value in the treatment of oranges for storage. Finally, work has been carried out on the developmental anatomy of orange rind.
Miss Valerie May, Linnean Macleay Fellow of the Society in Botany, has carried out experiments to determine the effect of different concentrations of a mineral nutrient on a plant’s resistance to drought. In particular the effect of nitrogen has been studied. The effect of potassium and its interaction with nitrogen is also being examined. Helianthus has been used, as this plant is particularly suitable, for the technique employed, of analysing drought resistance by means of serial readings of a plant’s height. In earlier
iv PRESIDENTIAL ADDRESS.
Helianthus experiments it was shown that plants given abundant nitrogen quickly exhausted their water supply and so suffered severely after a drought of only a fort- night, whereas smaller nitrogen-starved plants were more economical with their water supply and thrived after a drought lasting nearly four months. Further, in these two groups of plants there was no significant difference in the rate of loss of water per unit area. Thus the effect of the difference in concentration of nitrogen on the resistance of a plant to drought, might be only imdirect, through plant size affecting the rapidity with which a given supply of water is exhausted. In a second Helianthus experiment, drought was measured in terms of the volume of water used rather than as the time during which no water was provided. The results will determine whether different concentrations of nitrogen and potassium affect the drought resistance of Helianthus other than by plant size and rate of use of water, both of which factors may be compensated for by root development in the field. Serial readings have been taken of leaf-area and water-use in addition to plant-height. A paper, ‘““A Survey of the Mistletoe of New South Wales’, will be published in the next Part of the ProcrEpines, while a second, to be published jointly with Professor EH. Ashby, has been prepared for publica- tion in the Procrrpines. This paper gives some results of experiments on drought resistance. - :
Mr. John Allan Dulhunty, Linnean Macleay Fellow of the Society in Geology, has made considerable progress in the study of the stratigraphical arrangement of the torbanite deposits in the Upper Coal Measures of the Kamilaroi Basin. The general stratigraphy of the Western Coal Fields has been studied, and a stratigraphical frame- work has been obtained, which is now being used for the purpose of determining the various horizons occupied by the different torbanite deposits. Important developments have been made in connection with the classification of the different types of torbanite and associated materials, and the results obtained from the study of special physical and optical properties of torbanite, are being applied to field and laboratory problems. He has devised special apparatus for studies in the general microscopy of torbanite, and progress has been made in the investigation of micro-constitution and structure.
Miss Margaret Cumpston, Linnean Macleay Fellow of the Society in Zoology, resigned her Fellowship on 30th April, 1940, but before doing so, she prepared a paper which contains a summary of observations on the family Scarabaeidae with a bibliography of the literature of this important economic family of beetles. :
Six applications for Linnean Macleay Fellowships were received in response to the Council’s invitation of 25th September, 1940. I have pleasure in reminding you that the Council reappointed Miss Ilma M. Pidgeon and Mr. J. A. Dulhunty to Fellowships in Botany and Geology respectively for one year from ist March, 1941, and appointed Mr. Mervyn E. Griffiths, M.Se., and Dr. Germaine A. Joplin, B.Sc., to Linnean Macleay Fellowships in Physiology and Geology respectively for one year from 1st March, 1941.
Mr. Mervyn Edward Griffiths graduated in Science at the University of Sydney in 1937: with First Class Honours in Zoology. He carried out research in the School of Zoology, University of Sydney, for several years as holder of a Commonwealth Govern- ment Research Scholarship and was awarded the M.Sc. degree in 1938. In the same year he was awarded a Science Scholarship of the Royal Commissioners for the Exhibition of 1851, carrying out research at the Montreal Neurological Institute, the Biological Laboratories, Harvard University, the National Institute for Medical Research, London, and the Courtauld Institute of Biochemistry, London. Mr. Griffiths’ researches, which have dealt particularly with glandular secretions, have been published in a number of papers in these ProceepINGs and several notes have also been published in Nature.
Dr. Germaine Anne Joplin graduated in Science at the University of Sydney in 1930, with First Class Honours in Geology and the University Medal, and was awarded the Deas-Thomson Scholarship in Geology for 1930, together with a Science Research Scholarship. In 1933, as holder of the Junior Fellowship of the International Federation of University Women, she carried out research at the University of Cambridge, for which she was awarded the Ph.D. degree. Since returning to Australia in iM)syy5 ID)
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Joplin has been employed as acting-assistant lecturer in the Department of Geology, University of Sydney. She has carried out a number of geological investigations and the results of these researches have been published in British and Australian scientific journals.
During the coming year Miss Pidgeon proposes to complete the study of the anatomy and physiology of Hucalyptus globulus and also hopes to continue work on the statistical analysis of regenerating vegetation at Broken Hill. She also proposes to continue work on the physiology of water loss from oranges, and intends to complete her ecological studies of the central coastal area of New South Wales. Mr. J. A. Dulhunty will continue his investigation of the torbanite (oil shale) deposits of New South Wales. This will include a study of the environmental conditions of deposition and metamorphic evolution of the torbanite deposits and a microscopical study of the detailed structure of the gelosite and retinosite bodies in the torbanite. Mr. M. Griffiths intends to investigate the relationship of the secretions of the duodenum and the anterior lobe of the pituitary gland to carbohydrate metabolism with particular reference to diabetes mellitus. Dr. Germaine Joplin proposes to complete a petrological study of the Ordovician rocks at Cooma, investigating the relations between the igneous intrusions, the folding and the regional metamorphism. We wish them all a successful year’s work.
The concluding part of Volume Ixv of the Society’s ProckepINGs was issued in December. The complete volume (568 plus xl pages, seventeen plates, and 605 text- figures) contains thirty-four papers on various branches of Natural History. The volume was again larger than usual, as Council decided that the additional cost of publication of the Macleay Bacteriologist’s extensive paper on the nitrogen economy of Australian wheat soils should be borne by the Income Account of the Bacteriology Fund. On account of rationing of paper, which began in the latter part of the year, it was decided to omit from the ProcrEpineés the printed list of donations and exchanges, the list of members and the biological portion of the index. Moreover, the amount of words on the printed page was increased in Parts 5-6 by altering the length of the line from 28 ems to 30 ems, and the depth of the page from 43 to 48 ems.
Exchanges from scientific societies and institutions totalled 1,383 for the session, compared with 1,865, 1,860 and 1,838 for the three preceding years, this marked decline in the number of exchanges being due mainly to the war.
THE HEFECT OF SETTLEMENT UPON THE NEW SoutH WALES FLORA.
In 1770, when Sir Joseph Banks made his first botanical collection in Botany Bay, he had an opportunity of studying a virgin flora which was apparently little affected by the few human inhabitants. With the arrival of the First Fleet in 1788, however, the first impact of the white man was made on the vegetation, and since that time the effects of settlement have produced many striking changes in the flora. It is probable, as indicated by Osborn (1928), that outside human interference with the indigenous flora does not necessarily date from comparatively recent’ years. It possibly goes back to a remote age, as early visitors to this continent were very likely to have brought plant seeds with them. But the influence of human voyagers prior to 1770 must have been very small, and it is only since the recent settlement by white men that any appreciable changes due to human interference have been made.
The effect on the flora in many districts has naturally been most marked and far reaching. It is, of course, true that many areas show little or no effects of settlement, and it is probably equally true that many of these areas will retain more or less indefinitely their distinctive flora quite uninfluenced by the activities of the white man. For, apart from natural reserves, there are many parts of New South Wales which are quite unsuited for settlement of any kind and sufficiently remote to be left undisturbed even in the midst of an expanding population. Such areas seem quite unsuitable for any likely utilization,-and it is probable that they will always provide examples of natural flora uninfluenced by man.
Many parts of the Hawkesbury Sandstone areas seem to possess an uninviting barrenness which ensures a virgin flora. Parts of the Tablelands seem unlikely to be utilized for any purpose, and the arid country of the far west is, in many cases, unstocked
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and likely to remain so. The Commonwealth Year Book for 1939 indicates that about 8% of New South Wales is unoccupied, the remainder being alienated, in the process of alienation, or held under leases or permits. It is probable, however, that at least some of the alienated land is little, if at all, affected by human settlement.
But the effect of settlement has had very striking results in many parts of the State and it is these which form the subject of this address.
When the white man came into this country he found land which, with a few exceptions, seemed singularly lacking in suitable food plants. He was compelled to clear away the forest and scrub cover to make way for his houses, roads and crops. He brought in domestic animals and made available suitable pasturage for them. In the pursuit of these activities he laid waste the native flora and introduced alien plants and animals, either intentionally or accidentally.
Broadly speaking, the effects of settlement on the flora can be studied under the following sections:
Effects of clearing land for roads, railways, towns, villages and homesteads.
2. Effects of clearing and utilizing land for crops.
3. Effects of utilizing land for pasture, including the introduction of domestic
and other animals.
The effects of fires.
The introduction of insect and fungal pests.
6. The effect of usefulness to the white man upon subsequent distribution of individual plant species.
pa
ote
EFFECTS OF CLEARING LAND FOR ROADS, RAILWAYS, TOWNS, VILLAGES AND HOMESTEADS.
The actual areas cleared for such purposes are, of course, only small, but they are of importance in establishing centres from which the alien or introduced flora can become established. Many naturalized species have originated as escapes from garden cultivation, and some of our most troublesome weeds are ones which were formerly introduced as desirable garden subjects. Hchium plantagineum (Paterson’s Curse) was introduced into the Albury district as a garden plant about 1875. It escaped on to a travelling stock reserve and was subsequently distributed over a wide area. To-day it is firmly estab- lished in many parts of the State, being declared a noxious plant in over 50 shires and 40 municipalities. Hichhornia speciosa (Water Hyacinth) was introduced to the northern rivers as an attractive flowering plant. It was placed in Swan Creek on the Clarence River and found conditions so congenial that in two years it had taken possession of the creek. Subsequently pieces were taken and grown in other water-ways by people attracted by its ornamental character. In a few years it had grown so luxuriantly that it became a serious problem in northern rivers and streams.
Hypericum perforatum var. angustifolium (St. John’s Wort) was also very probably first grown as a garden plant, but it soon escaped from cultivation and to-day it has been proclaimed noxious in a very large number of shires and municipalities. Although species of Opuntia were probably first brought to Australia as food. plants for the cochineal insect, the true pest Pear was very probably introduced as a garden or hedge plant. The heavy infestation in the Scone district appears to have been started by Dr. Carlisle, who introduced it to his station garden in 1839, his manager subsequently planting it through the paddocks as a standby for stock during drought periods. So rapid was the spread of Prickly Pear from various centres that in 1925 some 60,000,000 acres were covered by it in Queensland and New South Wales. Since that time the area has been very much reduced by the activities of the larvae of the introduced moth Cactoblastis cactorum.
A fairly large proportion, however, of naturalized plants which have escaped from cultivation, shows little tendency to invade natural areas unless the way is prepared by considerable human interference. Many of them have little liking for straying beyond the artificial conditions created by man, and, although they have been recorded as naturalized for many years, cover only very small areas.
Alien plants are common along roadsides passing through natural country which is neither cultivated nor stocked, but there is usually very little evidence of them
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spreading beyond a few yards from the road except at points which show signs of human interference.
When travelling along railway lines it is quite noticeable that the alien plants usually occur in a narrow fringe along the lines and do not invade to any appreciable extent the adjoining natural areas. It is also often noticed that the aliens are most conspicuous on moist better class soils on level ground and do not occur so frequently on dry soils on embankments. In some cases, of course, species like Rubus fruticosus (Blackberry) and Lantana camara invade adjoining areas, but even then their successful competition with the native flora is limited to certain areas.
A minor result of roads and rail lines being taken through densely covered country is the change in the composition of the flora along the fringe of the clearings due to the greater development of light-demanding or light-loving species.
Where roads or railways pass through cultivated or pastoral areas they are far more important as centres for the distribution of introductions. This is particularly the case where stock use the roads for travelling, as their fleeces or coats carry the seeds of plants from other districts. On country stock routes the vegetation has naturally undergone many changes, being subject to severe grazing, trampling and the deposition of dung. Stock travelling in trucks along railways spread the seeds of plants in dung or in other ways, railway embankments being often characterized by a flora very different to that of the surrounding country.
EFFECTS OF CLEARING AND UTILIZING LAND FOR CROPS.
The actual amount of land in New South Wales which has been under cultivation at one time or another is relatively small, the New South Wales Statistical Register for 1939 showing 7,044,038 acres as under cultivation, 3,199,626 under sown grasses, and 3,565,371 acres as land previously cropped, but not ploughed during the year.
These combined figures indicate that the total area which has been sown or cropped at any time is only about 7% of the total land area of the State. The area suitable for cultivation is estimated at between 15% and 16%.
Alien plants introduced on to such cultivated areas, however, spread to adjoining country to some extent, especially where the flora is disturbed by human interference other than direct cultural operations. The native flora on areas utilized for cultivation has, of course, very largely disappeared and been replaced by deliberate introductions such as food and forage plants, or by accidental introductions especially of those weeds which have shown particular ability for following the plough in most parts of the world.
At present there are some 546 species which have become naturalized in New South Wales, including 128 grasses. -These come from many different countries, but the great majority are natives of Hurope, Africa and North and South America. Countries having a somewhat similar climate naturally supply many of our introduced plants, so that regions round the Mediterranean, South Africa and South America are well represented. China and Japan contribute only six species, including one grass.
The family Gramineae contains the largest number of introduced species, many of which have been purposely brought here for their fodder value. The next most important family is the Compositae, which has supplied 75 species to our naturalized flora. Fifty species of Leguminosae have become established, including many useful fodder plants such as the various species of Medicago and Trifolium. Other families which are more or less strongly represented are the Cruciferae, Caryophyllaceae, Scrophulariaceae and Solanaceae.
These aliens, apart from those brought in as useful crop or forage plants, have been introduced in a number of ways. The principal source was impurities in seed imported for agricultural or pastoral purposes. For many years there was no check on such introductions, and a very large number of weeds and undesirable aliens must have become established in this way..
Breakwell (1918) gives an example of White Clover seed which contained 37,440 seeds of impurities to each pound. In 1908 the Federal Quarantine Act was passed which included an appendix forbidding the entry of certain plants. Gradually the
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regulations enforcing this act were tightened so that at the present time seed impurities are not so likely a source of further introductions. As an example of seed impurities a fairly recent sample of perennial rye grass tested at the New South Wales Department of Agriculture showed approximately 12% of foreign seed, representing fourteen different species. The number of seed impurities per pound was estimated at 27,500. Some samples tested have shown impurities as high as 22%.
It is very likely that many plants have been introduced in fodder for stock during drought periods. Following such drought years and the importation of fodder from other countries, there has usually been local development of species new to this country. In some cases these have failed to retain their original hold, but in others they have found conditions to their liking and have become firmly established.
Quite a number of plants have been introduced in packing round goods, 35 species of plants being recorded in one occasion in the packing around some glass beakers. The ballast from ships emptied out on beaches or coastal land has been responsible for the entry of quite a number of aliens. Several interesting plants, for example, have been found at Stockton near areas where ballast had been discarded.
Noxious Weeds.
The naturalized flora has contributed most of our troublesome agricultural and pastoral weeds, the wide distribution of which has been helped by their rapidity of growth, great powers of reproduction, and the absence of natural enemies. During recent years Chondrilla juncea (Skeleton Weed) has proved particularly troublesome and has provided a serious problem in wheat-growing areas. Its rapid growth has been phenomenal since 1917 when it was first recorded, and to-day it covers many thousands of acres. Its wide distribution is due largely to its very efficient seed production and dispersal, its deep rhizomes, and its comparative unattractiveness to grazing animals. The most troublesome weeds contributed by alien floras include Inula graveolens (Stinkwort), Lepidium draba (Hoary Cress), Hypericum perforatum var. angusti- folium (St. John’s Wort), Convolvulus arvensis (Bindweed), Rubus fruticosus (Black- berry), Xanthium spinosum (Bathurst Burr), Alternanthera echinata- (Khaki Weed), Centaurea calcitrapa (Star Thistle), Hchium plantagineum (Paterson’s Curse), Lantana camara and Rosa rubiginosa (Sweet Briar), but there are many others which have provided a serious problem for our landowners. In addition, some introductions, such as Conium maculatum, Homeria collina, Salvia reflera and Lamium amplexicaule, are poisonous to stock and have been associated with stock losses.
Some of the naturalized species have become extremely widely distributed, but are not regarded as troublesome weeds, being usually quite easily controlled if desired. Included in this group are Plantago lanceolata, Polygonum aviculare, Chenopodium album, Capsella bursa-pastoris, Euphorbia Peplus, Anagallis arvensis, Sonchus oleraceus, Malva parviflora, Amaranthus spp., Rumex spp., Medicago spp., and Trifolium spp. These are mainly free-seeding, rapidly maturing annuals, which have a marked ability for adapting themselves to a wide range of soil and climatic conditions.
Native Plants as Weeds.
Although the aliens provide most of our weed problems yet some of the native species have found the new conditions created by man’s interference quite favourable to their development. During recent years particularly, there has been a distinct tendency for native species to become rather troublesome to the farmer and pastoralist. Bassia Birchii (Galvanized Burr) has spread to a very considerable extent, especially in the north-west, and has been proclaimed a noxious plant throughout the State. Until about twenty-five years ago it was by no means common, but it gradually asserted itself in heavily stocked areas as its spiny nature renders it unattractive to stock. The spiny fruits adhere readily to wool and permit distribution over wide areas. After rain on overstocked land it often comes up in considerable quantity, and in some cases is even invading agricultural land. The closely related species Bassia quinquecuspis has also become moderately troublesome, but is not regarded so seriously. It becomes detached from the ground, and is blown along by the wind, being one of the several
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plants known as ‘Roly-poly’. The dried plants are often piled up along fences making these more likely to be destroyed by fire by providing additional fuel.
Solanum cinereum (Narrawa Burr) is another spiny native plant which has been proclaimed noxious in quite a number of shires and municipalities. Tribulus terrestris (Caltrops) and Hmez australis (Cat’s Head) are further examples of native plants which have become troublesome chiefly because of their spiny fruits. Quite recently it was reported that Hremocitrus glauca was spreading in the Warren district on black soils as its rather prickly nature made it objectionable to stock, and it did not appear to be palatable in any way. Carex longifolia, one of the native sedges, has become fairly troublesome in pastures of the Illawarra and South Coast. It has harsh sharp-edged leaves which are avoided by stock. Fairly large tussocks are formed, occupying in some cases up to 25% of the paddocks. Abundant seed is produced during the summer months and the species is steadily increasing the area under its control.: It appears possible that in some districts it will in time take possession of pastures or seriously diminish their value, especially on the poorer types of soil. Free-seeding shrubby species like Cassinia arcuata and Olearia viscidula often appear on cleared land and soon take possession. Kunzea corifolia and Dodonaea triquetra also tend to spread over cleared areas. Sida rhombifolia (Paddy’s Lucerne) is another of the native plants which have prospered under the new conditions following settlement.
Increase of Mistletoe.
During recent years there has been a marked increase in the effects of Mistletoe in many districts. The problem is becoming quite a serious one, as many valuable trees are being killed by this parasite. In other cases trees are losing their vigour or are becoming mis-shapen. Most observers agree that the amount of infection is far greater than previously, but the reasons for this increase are by no means clear. It seems, however, that the problem is partly one resulting from the effects of settlement. The results of mistletoe infection are usually much more apparent on fairly open country than on closely timbered areas. Mistletoe is quite rare, for example, in rain-forest, and is essentially a light-loving plant. As the country is opened up infection is more common, possibly because of the greater light provided, or because the birds carrying seeds have fewer resting places. If there are fewer trees for the mistletoe bird on which to alight, the chances of an individual tree being infected must be increased. If this were so, however, the number of trees infected may not be actually increased although the effects of the parasite may be more noticeable. At all events the spread of Mistletoe does appear to be associated with the opening up of the country, and is probably one of the results of settlement. -
Some observers also state that the increase in Mistletoe is due to the decrease in the numbers of koalas and opossums brought about by the demand for their skins. Evidence on this point, however, is contradictory, and it is by no means definite that koalas or opossums exercise any great effect in controlling Mistletoe. In some western districts, Mistletoe is relished by stock and is regarded as a useful standby during bad periods. One effect of settlement in this case might be the decreased quantity of Mistletoe in such districts, but no reliable observations are available on this point. In many parts of the State, however, the disturbance brought about by settlement has set up the problem of increasing parasitism of valuable trees and shrubs.
Possibilities of Further Additions to the Naturalized Flora.
No doubt the number of alien species established in New South Wales will increase from time to time, but the recording of new aliens is becoming far less frequent than formerly. The factors. operating against the introduction of new species are the more rigid and efficient enforcement of legislation governing seed impurities and noxious plants, the less tolerant attitude of the landowner to aliens on his property, and the general effects of closer settlement.
The farmer and grazier no longer view with easy complacency the appearance of a new plant on their property. They tend to regard the strange plant as a potential trouble maker, and take steps to prevent its establishment. Of recent years the question of
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noxious weeds has become a fairly acute one, and the farmer is far more concerned with the weed problem than formerly. In addition governmental authorities take the necessary steps to secure the eradication of any new arrival which has a bad record in other countries, or which is likely to prove troublesome in any way. For example, some years ago Allium vineale (Wild Garlic) made its appearance at Berridale on the Southern Tablelands. It is a fairly common weed in America, where it is troublesome in fields of small grain and in pastures, adding a garlic taint to wheat and dairy products. It has particularly efficient methods of reproduction, spreading from under- ground bulbs, aerial bulbils and seed. The aerial bulbils, being much the same shape and size as wheat grains, are difficult to separate from seed wheat and it therefore appeared to have serious potentialities as a noxious weed. Steps were accordingly taken to ensure its complete eradication, and warnings were issued to landowners to be on the outlook for it in other districts. The alien plant, recently arrived on our shores, does not experience so hearty a welcome as in former years.
Some recent introductions, however, have appeared to spread rather widely and rapidly. The Central American plant Gomphrena dispersa was first recorded in New South Wales only about five years ago, but since that time it has appeared in quite a number of localities, and is evidently increasing.
Regeneration of Abandoned Land.
Land once under cultivation but subsequently abandoned generally carries, at first, a high proportion of introduced species which, however, are often gradually replaced by the native ones. In other words, provided man’s interference is withdrawn, the native species usually tend to dislodge the aliens. Hamilton (1919), in a study of salt marsh vegetation, describes an area at Cook’s River where the land had been laid down in pasture. He found that the original vegetation was reappearing, and already some of the shrubby species had recaptured small areas and were driving back the introduced vegetation. Adamson and Osborn (1924) state that stringybark forests rather rapidly recapture cleared ground when this is abandoned. The forests developing on these cleared areas soon assume the same general features as the surrounding untouched portions, although certain species when once eliminated seem to have difficulty in returning. It was noted, however, that very few aliens survived.
Such reversion of abandoned land to the native flora seems to be quite the general rule, although in cases where the area is invaded by such vigorous competitors as Black- berry, Lantana and Prickly Pear the native plants have difficulty in re-establishing themselves.
THE EFFECTS OF UTILIZING LAND FOR PASTURES.
Probably the most far-reaching effect of settlement in New South Wales upon the indigenous flora was that produced by the introduction of animals, the grazing habits of which differed profoundly from those of the native fauna. With the white man came his Sheep, cattle, horses, camels, foxes, and goats, all of which have become naturalized or live under conditions very closely approaching the wild state. One of the most important introductions, however, was the rabbit, which multiplied to such an extent that it soon became a major problem for the pastoralist.
The methods of grazing of these introduced animals were very different to those of the native marsupials. Osborn (1929) has pointed out that the damage done by kangaroos, even when they are numerous, is probably quite small. In observations at the Koonamore reserve he found that the marsupials did not graze closely, but merely pruned the grass tufts, leaving three or four inches of the leaf untouched. On the other hand, sheep and rabbits graze closely and the plants are frequently killed by heavy or sustained stocking.
Since settlement the number of stock in New South Wales has risen steadily. In 1939 there were approximately 49,000,000 sheep, 3,000,000 cattle and 548,000 horses. In some years the number of sheep has reached 53,000,000 and the effect on the native flora of supporting these animals has been enormous. Sheep tend to be very selective in their feeding, preferring low-growing fine plants. They relish the most tender shoots
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and avoid as far as possible the coarser tall-growing species. Horses are even more selective, often concentrating on patches of the finer grasses until eaten out. Cattle, on the other hand, will consume the coarser grasses and herbage far more readily.
The rabbit, which became a pest after 1880, exercised a profound effect on the vegetation, being responsible for reducing the carrying capacity of the land to an alarming extent. Rabbits graze closely, and in addition, are most destructive of the perennial flora, including shrubs and trees. Woody plants, especially, find survival and regeneration difficult to accomplish in rabbit-infested country. They are often ring- barked, and many edible trees have been destroyed by rabbits eating the bark away from the trunk and even the lower branches. When reasonable amounts of feed are available rabbits exhibit certain selective habits, preferring some species to others. Peacock (1908) has pointed out that rabbits do not care for one of the White Ever- lastings (Helipterum sp.), and as a consequence this plant had taken possession of large areas.
Effect of Stocking on Purely Natural Pastures.
In the first place we might consider the effect of stocking on natural pastures which have not been sown, cultivated, or top-dressed in any way. Such pastures constitute the great bulk of land utilized by stock, particularly in the western division of the State. In many parts of New South Wales the native flora, although quite adequate for the needs of the indigenous animals, could not be expected to withstand the heavy demands of large numbers of close grazing animals. Osborn (1928) has pointed out that the indigenous grasses have not the underground renewal buds often associated with grasses on areas carrying a large herbivorous fauna. In addition, very few of the native plants produce rhizomes which would enable them to resist the effects of stocking. Some of our grasses, however, notably Danthonia bipartita, Eragrostis eriopoda and Neurachne Mitchelliana, have buds which appear to be better protected from grazing by the fact that they are very close to the ground or are situated just below soil level. In addition some protection to the buds seems to be given by woolly bracts. However, a fairly large proportion of our grasses and herbage plants appears more suitable for the sustenance of nomadic marsupials than the needs of modern, concentrated, stock- raising practices.
The temptation to exploit the pastoral wealth of the country soon led to an increase in the number of flocks and herds. The general tendency was for stock to eat out the more favoured species, resulting in a gradual alteration of the flora accompanied by a decrease in the carrying capacity of the country. In extreme cases practically the whole of the vegetation was destroyed. On most areas, however, the effects of stocking became apparent through the gradual disappearance of those species favoured by stock and which had limited powers of reproduction or little capacity for withstanding the effects of grazing. For example, it is generally recognized that Themeda australis will not stand much stocking and soon disappears from pastures. It is handicapped by the facts that it is relished by stock and has rather poor reproductive powers. The various species of Danthonia also tend to disappear under stocking. On the other hand species of Aristida and Stipa usually increase their numbers owing to comparative unpalatability and perhaps to their capacity for withstanding depleted soil fertility. Chloris truncata is another grass which is not so affected by stocking and which is usually one of the early colonizers of over-grazed land. This is probably due to its production of very abundant seed with high germination capacity, whereas many of the other grasses have rather poor seed production and low percentage of germina- tion. Tragus racemosus is another species not so adversely affected by stocking.
In some paddocks after grazing Hragrostis leptostachya appears to be quite prominent, although a very palatable grass. It is probably aided by its habit of growth which is rather low and mat-like, and therefore better able to withstand certain types of stocking. In any case, it is apparent that some native species are better equipped than others to withstand grazing by introduced animals, and it is inevitable that such plants will become more prominent while others disappear.
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The introduction of large numbers of animals also provides a vehicle for the wider distribution of those species producing burr-like fruits or seeds which can become attached to fleeces and coats. It is probable that the various species of Calotis have become more widely spread because of this factor, and possibly Stipa and Aristida species are favoured in the same. way. Other native species adapted for distribution in the coats or fleeces of animals are Tragus racemosus, Cenchrus pauciflorus, Acaena spp. Glycyrrhiza psoraleoides, Desmodium spp., Oncinocalyx Betchei, Bassia spp. and Daucus brachiatus. Among the introduced plants might be mentioned Medicago spp., Xanthium spinosum, Rumex spp. and Marrubium vulgare.
Apart from actual grazing, heavy stocking may have the effect of loosening or pulverizing certain soils, resulting in drifting of the surface portion and exposure of the hard clay underneath. Suitable seed-beds are no longer available, and gradually the whole of the vegetation is destroyed, giving rise to the “scalded” plains of western areas. Clayey soils which are at all heavily stocked become hardened and offer very adverse habitats for regeneration of plants. Osborn, Wood and Paltridge (1935) found that the hard loam soils supporting Kochia sedifolia rapidly lost the surface mulch of fine soil under the combined influence of trampling by stock and of wind. This condition offered great obstacles to the establishment of any seedlings.
Broadly speaking, in New South Wales the effects of stocking on the native flora depend on the climatic and soil conditions of the area concerned and the nature of stocking. In many western portions of the State little or no clearing has been necessary. Such areas support two plant communities consisting of hardy perennial shrubs or trees and a large variety of annual herbs. The annual plants grow very quickly after rainfall, flowering and seeding in a very short time. Botanically this annual flora consists of a very wide range of species, most of which are eaten by stock during the short time they are available. But they are able to flower and mature seed in so short a time that stocking seldom results in wiping them out. The shrubs or small trees which constitute the permanent part of the vegetation consist largely of species of Acacia, Myoporum, Eremophila, Casuarina, Atriplex, Bassia, Kochia, Geijera, Capparis, Owenia, Grevillea, Atalaya, Hakea, Apophyllum and other genera. This flora provides the main reserve supply of fodder and is, unfortunately, often the most affected by continual stocking. Seedlings are destroyed and further growth is made difficult by continual trampling preventing the formation of suitable seed-beds. Rabbits destroy mature plants by ring-barking them, apart from eating seedling growth. It is there- fore common to find very little development of seedlings and young growth of most woody shrubs and trees in areas subject to continuous stocking. Indeed, when travelling around New South Wales, one is impressed by the almost total absence of young trees or seedlings in most districts where settlement has taken place. The few trees left in many paddocks are becoming aged and unsuited for the provision of efficient shade and shelter. A great deal of planting will be necessary in many parts, although much could be done by encouraging natural regeneration through the exclusion, of stock from selected portions.
Collins (1924) states that very few, if any, seedlings of Mulga were seen in a strip 300 miles in length in the far west of New South Wales, and that local observers asserted that crops of seedlings were very rare. On the other hand Nichols (1988) quotes Melville as showing evidence that stocking in Western Australia has probably little effect on Mulga regeneration, as young seedlings are distasteful to stock and are hardly ever touched. This is stated as probably due to the nature of the resinous secretions on the phyllodes and stems which vary according to the age of the plant, seasonal conditions, and the variety of the species. The tree is not considered edible until it reaches a height of about twelve feet. These are most interesting observations, but it is not certain how they are borne out by the behaviour of Mulga in New South Wales. It is a widely accepted opinion that Mulga seedlings are destroyed by stock, but more definite investigations are necessary on this point. Botanically, Acacia aneura, which is the most common species known as Mulga, is extremely variable, and it is quite possible that a number of very distinct varieties are involved. In different parts of
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Australia the name Mulga is given to quite a number of distinct species of Acacia, and conflicting statements may therefore be due to the fact that reference is being made to entirely different species.
On western areas which are fairly heavily covered with trees or scrub some clearing is necessary. This is usually followed by good grass growth, but the tendency then is to overstock, resulting in the increased development of non-edible shrubs. The growth of these unpalatable species is also assisted by understocking of the rough growth in seasons of good rainfall. During recent years such species as Cassia eremophila, Cassia artemesioides, Bertya Cunninghamii and Hremophila Mitchelli have overrun some districts and are spreading from the poorer soils to better class ones. Carn (1938) states that on some areas there are 250 plants of Cassia spp. to the acre. Such growth of non-edible species has, of course, some value in preventing wind erosion.
In other parts of the State it is necessary to carry out a good deal of clearing in order to establish pastures. In many cases such clearing has been excessive, not even sufficient trees being left for shade and shelter. After clearing there is usually a considerable alteration in the ground flora due to the development of grasses and rosette plants. An apparently stable grassland community is produced which, how- ever, is usually only maintained by grazing. If animals are excluded the tendency is for shrubs and young trees to reappear.
Regeneration on Areas following Protection from Animals.
It is frequently noted that areas fenced off from stock and rabbits show quite striking natural regeneration and a definite increase in the size, number and variety of plants and species constituting the ground flora. Provided stock are excluded, the natural flora has considerable recuperative powers, the marked improvement in the cover being due either to increased vigour and size of the original plants, or to the development of new plants. Fenced off areas in the neighbourhood of towns in western districts provide the botanist with the best opportunity of studying the natural flora, especially if he is in search of good specimens. Along many western rivers to which stock have access, for example, it is rare to see young plants of the River Gum, Hucalyptus camaldulensis, or of the River Oak, Casuarina Cunninghamiana. If such areas are fenced off, however, young seedlings soon make their appearance. Some western landowners have estab- lished small breakwinds or shelter belts by the simple expedient of fencing off strips, allowing regeneration to take place, and subsequently planting larger growing trees in the shelter provided by the naturally regenerated plants. An interesting example of regenera- tion following protection from grazing was that resulting from the efforts of the late Albert Morris in the Broken Hill district. wing to the cutting of trees and larger shrubs for fuel and mining timber, and through the effects of very heavy stocking, the land in the neighbourhood of Broken Hill had become practically denuded of vegetation. Sand drift was common, and the difficulties in the way of planting trees seemed insuperable. Morris, however, was instrumental in having areas completely fenced off from stock, as he was convinced that the vegetation would “come back” if rested. The natural regeneration following on fencing justified his judgment, and he took advantage of the cover provided to plant out young trees. The experiment is only in the early stages, but it promises to yield far-reaching results which should be of great assistance in over- coming similar problems in other parts of the State.
In a statistical analysis of these areas Pidgeon and Ashby (1940) found that protection given by fencing over a period of less than two years increased the density of perennial plants on areas previously heavily grazed. There was also evidence that fencing increased perennials relatively more than annuals, both in variety and numbers. In some cases the number of annuals was found to be considerably lower in fenced than in unfenced areas, probably because of the greater competition offered by strong growing perennials. It was also observed that, in some cases, although the difference was very great in the amount of vegetation existing in fenced and unfenced parts, this was due to the increased growth of the individual plants rather than to an increase in numbers. Another interesting observation was that protection decreases the number of weeds or undesirable species while increasing the number of perennials, particularly of palatable
XIV PRESIDENTIAL ADDRESS.
species. A great deal of work remains to be done before we know very much of the detailed effects of regeneration on areas following protection from animals, but we know enough to feel sure that this method of allowing natural regeneration to take place is one of the most promising ways of remedying, to some extent, the tremendous damage done to our natural pastures by continuous stocking. Protection from stock, although beneficial, is not sufficient as it is also necessary to exclude rabbits and to ensure their destruction within the area. At the Koonamore reserve the perennial flora was not restored after twelve years’ protection from stock, and this result may have been due in part to the fact that, although the fencing was rabbit-proof, rabbits were common within the area and at times were numerous.
Effects of Mineral Depletion and Lowering of Soil Fertility on Natural Pastures.
Apart from the effects of grazing the composition of the flora may be altered by the results of mineral depletion and lowering of soil fertility. Although wool itself is relatively low in mineral constituents, yet its removal year after year involves a steady depletion of the mineral substances in the soil. A thousand pounds of unscoured wool is quoted by Wadham and Wood (1939) as containing 54 lb. of Nitrogen as N.,, 0-7 lb. of Phosphorus as P.O,, 56:2 lb. of Potassium as K.O, 1:8.lb. of Calcium as CaO, 0:4 lb. of Magnesium as MgO, and 35:5 lb. of Sulphur. One whole sheep of 150 Ib. live weight, however, contains 5:3 lb. of Phosphorus, so that, on properties from which sheep are sold, there is.a much greater drain. The authors state that in southern Australia, where phosphate deficiency in soils is common, continuous grazing has almost certainly led to a depreciation in the type of herbage, due to the inability of many of the more valuable species to tolerate the low phosphatic status of the soil. A serious feature of phosphatic deficiency is the gradual disappearance of the more valuable natural grasses and their replacement by inferior species such as Bothriochloa decipiens or Stipa spp.
Bothriochloa decipiens (Red Grass) is an example of a species which has spread rapidly in some districts because of the effects of continuous grazing or cropping in reducing soil fertility. Moodie (1934) states that this grass has a wide range in New South Wales and is tolerant of extremely low fertility conditions. On better class soils it is not aggressive, but on poorer soils it soon becomes dominant and crowds out more valuable pasture plants. It grows fairly vigorously during spring and summer, and is eaten by stock, although they prefer other grasses if available. In good seasons, there- fore, it is rejected by stock and produces large quantities of seed, which help it in the gradual elimination of other species. It provides fair summer pasturage but very little winter feed. Many pastures of this grass develop Medicago spp. and Trifolium spp. during winter, but eventually these disappear and an almost pure pasture of Bothriochloa decipiens is established which gives poor quality summer grazing, and which has a negligible winter carrying capacity. The pastoralist: meets this problem by attempting to raise soil fertility through the use of superphosphate, and by sowing Subterranean Clover. After four or five years perennial grasses such as Lolium perenne (Rye grass), Dactylis glomerata (Cocksfoot) and Phalaris tuberosa can be established. The interesting point, however, is that on such areas the natural pastures have gradually been converted through the effects of stocking to an almost pure association of a comparatively unpalat- able native grass. This necessitates treatment aimed at the establishment of introduced species. It is unlikely that any methods will be adopted which would have as an object the re-establishment of the better class native species formerly occupying the area.
It has been customary to divide pasture plants in New South Wales into two groups, namely, those demanding high fertility soils, and those which tolerate low fertility types. In the first group are species like Lolium perenne, Trifolium spp., Phalaris tuberosa and, to a less extent, Paspalum dilatatum, all of which have heavy carrying capacity. In the second group are Sporobolus capensis, Chloris Gayana, Axonopus affinis and most of the native species. These are not so suitable for heavy stocking. The opinion is often expressed that the low fertility tolerant plants, which usually give poor grazing, are succeeding in crowding out the better quality plants over large areas in the State. On many parts of the North Coast, for example, Paspalum dilatatum is finding it difficult
PRESIDENTIAL ADDRESS. XV to compete against Axvonopus affinis. Continuous grazing certainly does appear to lead to a regression in the type of vegetation owing to the inability of many of the better class species to tolerate phosphatic deficiency in the soils.
Beneficial Effects of Stocking on Pastures.
The effects of stocking in producing pasture deterioration are so obvious that the reverse side of the picture is often overlooked. In a few cases at least the presence of stock has a beneficial effect on pastures in certain respects. Blake (1938) draws attention to such improvement in typically ashy downs to the north of Barcaldene in Queensland. Areas which had been consistently and heavily stocked with sheep for several years carried a good stand of Mitchell grass and herbage, whereas adjoining land, which had been idle for many years, had very sparse vegetation. The loose nature of the soil is given as the probable reason. Continual trampling by stock compacts such soils, enabling them to hold moisture better, thus inducing better growth.
Osborn, Wood and Paltridge (1932), in a study of the growth and reaction to grazing of Atriplex vesicarium, one of the perennial saltbushes, at the Koonamore reserve, found that moderately heavily grazed areas showed no significant ‘difference in the number of plants, but carried more healthy and vigorous plants. Grazing was observed to result in the mechanical removal of dead bushes, and to exercise a pruning of the live bushes, owing to the repeated removal of the terminal buds. Such pruning caused the develop- ment of lateral shoots and the formation of a more compact and vigorous bush. It was concluded that, under moderately heavy stocking, the health and vegetative vigour of the community was increased, and the area thus made more valuable for grazing. It was also observed that intermittent stocking was valuable in allowing seedlings to become established, and it was suggested that heavy intermittent stocking might be the most desirable type of stocking in saltbush country. On the other hand, lightly stocked saltbush country was found to be less healthy than moderately heavily stocked areas er even than completely unstocked country. This was attributed to the develop- ment of overcrowded communities, owing to the planting of seed by the hooves of sheep and the failure to remove old or dying plants by light trampling. On heavily over- stocked areas, of course, the vegetation was completely destroyed.
In many parts of the State the trampling of sheep has been found useful as a fairly | efficient and cheap method of covering grass or clover seed that has been broadcast.
Effect of Pasture Improvement on the Vegetation.
In the early days of settlement the natural grasses and herbage were relied upon to provide pasture. Improvements were made in the composition of the pasture by clearing and firing, but, as a general rule, no other methods were employed. Soon, however, the pastoralist, especially in districts of good rainfall, had to face the problem of replacing the natural vegetation with some more useful and productive type. In some cases, as for example on sandy coastal soils, the natural vegetation is poor, and the light soils are unable to support anything other than low-grade plants or weeds. In other districts continual stocking has reduced soil fertility and consequent carrying capacity. During recent years, therefore, there has developed a definite tendency to change from pure exploitation to a more intensive and intelligent utilization of the land.. The sowing of introduced grasses and clovers is by no means new, as some areas have been sown with Perennial Rye, Cocksfoot, and clover for many years past.
The introduction of Paspalum dilatatum, which did so much to establish the dairying industry, was brought about as far back as 1883. It was not, however, until 1920 that declining fertility led to systematic investigations with fertilizers. It was found that the main requirement was to raise soil fertility in respect to both phosphates and nitrogen. Most New South Wales soils are deficient in phosphoric acid, and the use of superphosphate was found to produce quite striking improvements in many districts. Pastures fertilized with superphosphate were found to develop clovers to a marked extent, this in turn leading to nitrogen accretion and increased fertility. When the fertilizer is applied it is customary to sow seed of suitable grasses and fodder plants, so that the vegetation on these grasslands is undergoing considerable changes.
Xvi PRESIDENTIAL ADDRESS.
Moodie (1940) refers to the increase in the area of improved pastures, pointing out that there were only 19,314 acres of top-dressed pastures in 1927, but in 1938 this figure had increased to 875,730 acres. The top-dressing of pastures is not necessarily accom- panied or preceded by cultivation. Only in a comparatively few cases is the area ploughed, but harrows or cultivators may be used to break the soil and cover the seed. All species recommended for sowing are introduced ones, and it is evident that there is in progress, in many parts of the State, a gradual conversion of natural grasslands to artificial pastures. In some districts and in certain sections of primary production there has always been a tendency to replace the natural vegetation entirely by introduced species. Wadham and Wood (1939) point out that it is approximately true that satis- factory dairying is seldom achieved in districts where native plants form the bulk of the vegetation. Dairying requires areas of fairly heavy rainfall, and these usually support dense growth of trees and shrubs. The natural herbage in such associations is generally scanty and usually consists of a few shade-loving species. When the ground is cleared, new plants suitable for pasture must be introduced, and these are almost always exotic species. In some dairying districts native grasses still form the bulk of the pasture, but with the increased popularity of the use of fertilizers such pastures will be gradually converted to introduced species. The native plants, generally, do not give the best returns on good soils where the rainfall is high, and therefore the effects of settlement in such districts will be ultimately to replace the natural vegetation with an exotic one. ;
In many parts of New South Wales, however, especially in the drier Western Division, there is no evidence to show that we can improve on the existing pastures by the intro- duction of alien plants. It is, of course, possible, that eventually some introduced plants will be found that will prove suitable for western districts, but the immediate prospect is that the native species will continue to provide the bulk of the vegetation.
MeTaggart (1939) is of the opinion that plant introduction in Australia, as a whole, is restricted to a definite fringe belt, although in New South Wales this covers over half the State. There is, however, a substantial part of the State which is unlikely to be suitable for the establishment of exotic species.
Indeed it is generally true that native pastures throughout the State are not markedly invaded by introduced species, except where the soil has been disturbed or fertilized. There are, however, a few introduced plants which show ability for invading natural pastures. The various species of Medicago have spread very widely over the State, probably because their burry fruits are carried about by stock. They are so common and so firmly established that many landowners regard them as native plants. The several species of Vulpia also occur frequently in native pastures. These are free- seeding annuals which make rapid growth in early spring before the native grasses show much development. Koeleria phleoides, Hordeum murinum and Briza spp. are other aliens which are found widely throughout the State. In coastal areas Paspalum dilatatum has spread far beyond cultivation areas, although not so,common on land which is not subject to man’s influence in some way or another. Axonopus affinis spreads through the natural vegetation in North Coast districts, and the short-lived Poa annua makes its appearance under a wide range of conditions.
It might be concluded that the introduction of fodder plants and grasses and the wider use of fertilizers and grassland improvement methods have led to the replace- ment of the natural vegetation in many districts. The introduced plants in some cases have invaded the natural pastures, but on the other hand have not greatly altered their composition. Unless disturbed by cultivation or by the use of fertilizers, the natural pastures are likely to continue to consist very largely of native species.
THE EFFECTS OF FIRES.
Although naturally it is impossible to bring forward statistical proof it is reason- able to assume that, since settlement by the white man, bushfires have become far more frequent and widely distributed. Fires arising from natural causes have always existed but the great majority of fires are caused by human agency, either deliberately or through carelessness. No doubt the aborigines used fire when hunting game and it is probable
PRESIDENTIAL ADDRESS. Xvil
they fired grasslands in order to promote fresh young growth which would attract the animals they desired to hunt. It is possible that fire was used by them in a number of ways and at fairly regular intervals, but the extent of fires caused was probably small. Some evidence, however, has been brought forward to indicate that in some districts at least fires were common before the advent of the white man and may have actually decreased since his occupation. Howitt (1890) states that, in the Gippsland district of Victoria, country which was once open grassland was now covered with sapling growth of Eucalypts. The coming of the white man had resulted in the development of forests on grassland, and he attributed this to the less frequent occurrence of fires since settle- ment. The aborigines burnt off the grass either accidentally or intentionally each year preventing the seedling growth of trees. The white man excluded fire as far as possible, giving young tree growth opportunity to develop.
Domin (1911) formed the conclusion that some of the open forests of Queensland were not natural associations, but secondary ones changed mostly by bushfires started by aborigines. It is, therefore, difficult to estimate the extent and frequency of bushfires prior to settlement, but the general evidence points to the conclusion that, with possibly a few exceptions, fires have been far more frequent and extensive since the advent of the white man.
Settlers have used fire freely in order to clear land for cultivation and for the improvement of pastures by promoting fresh young growth of grasses. Many people have become careless in its use, with the result that widespread and disastrous fires have been far more common in recent years. One has only to go back to the hot, dry summer of 1938-1939 for an example of bushfires which have devastated wide areas. Few bushlands, especially those close to settlement, do not show signs of frequent firing, and such fires must have an effect on the vegetation varying in extent according to severity and frequency. They are usually most severe on forested areas or dense scrub- land as, apart from containing much inflammable material, these areas are.not utilized by private landowners, who naturally are not so concerned about preventing fires or controlling them once they have started. In addition such areas are usually remote from densely settled areas, so that fires are often not observed until they have obtained a good start. Grass fires are not so common unless deliberately started and are more easy to control. The effects of fire, therefore, are more commonly observed on forest land, on areas carrying fairly dense shrubby growth, or on poor soil types such as the Hawkesbury Sandstone soils, which may support considerable natural growth, but which are not fertile enough for crop or pastoral utilization.
According to severity and frequency, fires may cause total destruction, partial destruction, or light burning. Total destruction of plant life on an area seldom, if ever, occurs, especially as the native flora has unusual powers of renascence. In such rare cases, however, where all or most of the vegetation is destroyed, restoration depends on invasion from adjoining areas. Thus species in the neighbourhood which produce wind- borne seed and which happen to be seeding at the time will have a big initial advantage in the colonizing of the denuded area. Some of the Compositae such as Cassinea aculeata and Hrechtites species seem especially prolific on fired areas. However, there is always a certain amount of survival, and in many cases this is quite extensive, so that the association does not lose its identity. In other countries extensive fires appear to leave very few survivors of the original population, but it is characteristic of the Australian flora that the survival rate is high and that regeneration is rapid. Climax associations are seldom destroyed, and the effects of fire are less obvious than in other parts of the world. In many cases the plants forming the community, although considerably damaged by fire, establish themselves either by epicormic shoots or by shoots from root-stocks, ligno-tuiber's, or rhizomes. Many native species produce epicormic shoots, but the various species of Hucalyptus are most outstanding in this respect. The great majority of these produce suckers from trunks and branches very freely after fire, although a few do not. Jarrett and Petrie (1929) have pointed out that the big majority of trees in a Eucalyptus regnans Association were killed by fire, rarely producing new shoots. Regeneration, was only possible through seed, and if the fires were frequent this would become impossible.
B
XViil PRESIDENTIAL ADDRESS.
MeLuckie and Petrie (1927) state that on the Kosciusko plateau the Hucalyptus coriacea Association did not possess the rapid renascence characteristic of other Eucalypt forests. After six years there was little evidence of shoots on the stems of Hucalyptus coriacea and B#. stellulata, although shoots from the root-stock were common. In the most exposed situations no renascence was evident. It is often observed that Hucalyptus oreades and E. nitens find recovery difficult after fire. The ability to survive fires by Eucalypts appears to depend to some extent on the nature of the bark. Those species producing thick rough bark seem to insulate the cambium layer to some extent and are not so affected as the thinner smooth-barked species.
Apart from Eucalypts a number of other species produce epicormie shoots quite freely. Jarrett and Petrie (1929) quote Senecio Bedfordii as producing copious adven- titious shoots on the stem, and also mention Aster argophylla and Acacia melanoxylon. Other species which come readily to mind are Syncarpia laurifolia, Ceratopetalum gummi- ferum, Casuarina spp. and Banksia spp. Even some of the more tender semi-brush type of trees found along water courses such as Ceratopetalum apetalum, Tristania laurina and Hugenia Smithii, have strong powers of regeneration provided the fires are not too severe.
Renascence after fire is also greatly helped by the production of ligno-tubers by many shrubs and the ability of many species to shoot from the root-stocks. Beadle (1940) points out that ligno-tubers are a peculiar feature of many Australian plants and are most common in the families Proteaceae and Myrtaceae. Plants having such tubers are seldom entirely destroyed by fire as they are often buried deeply enough in the soil to avoid excessively high temperatures. Species such as XYylomelum pyriforme, Telopea speciosissima, Leptospermum spp., Banksia spp., and mallee Hucalypts usually show strong powers of renascence from the root-stock after fire.
The possession of rhizomes is also of assistance in withstanding destruction by fire. Such rhizomes are often little affected by fires passing over the area and shoot strongly, especially after good rainfalls. Pteridiwm aquilinum is a common example of a species which strongly asserts itself on land which has been fired. Shoots coming from the rhizomes are often so dense that other species have some difficulty in establishing them- selves although usually eventually successful. Jmperata cylindrica var. Koenigii also exhibits good renascence owing to its possession of rhizomes. Jarrett and Petrie (1929) quote Oxalis corniculata and Viola hederacea as other examples.
Apart from rhizomes some species produce bulbs or other underground organs of propagation which help their regeneration after fire. This is particularly common in the Liliaceae, Orchidaceae and some of the Gramineae. One peculiar characteristic of some native ground orchids is that they flower far more freely after a fire has passed over the area. A well known example of this is Lyperanthus nigricans.
Plants not possessing any of these aids to regeneration, however, depend on fire- resistant seeds which are present in the soil or on the plants themselves. Thus regenera- tion is by no means confined to regrowth of surviving plants, but is often largely due to seedling development. Williams (1940) has stated that the regrowth after fire of swamp tea tree in the coastal areas at Dromana consisted almost entirely of seedlings as the damaged shrubs did not produce suckers. The fire-resistant qualities of the seed of many Australian plants is very well known, the most common examples being provided by the families Proteaceae, Myrtaceae, and Leguminosae. The seeds of Acacia have a very hard coat which protects the embryo from damage, and it is a common experience for seedling growth to be greatly stimulated by fire passing over the area. Many landa- owners have been surprised to find a growth of Acacia on their land, following on grass or stubble fires. In some cases there has been no evidence of Acacia spp. in the district for many years, but the seed has lain dormant in the soil until turned up by the plough and subjected to fire. Growing plants of Acacia seldom recover after fire as they do not produce epicormic shoots or possess renascent root-stocks, regeneration thus depending on seed. The hard, woody fruits of Hakea and other genera of the Proteaceae are admirably adapted for survival after fire. The seed is well protected from all but the hottest fires, but the heat is sufficient to perform the useful function of opening the fruits
PRESIDENTIAL ADDRESS. IDX
and shedding the seeds. Hakea pugioniformis, for example, is often strongly in evidence on areas after fire. Species of this type possess a marked advantage over others. Actually fire by hastening the dehiscence of the fruits is a distinct aid to natural regeneration, especially as the ash and litter often provide a useful germinating bed. The seed of Callitris is also protected by the woody cone. Ability to survive fires, however, is not limited to those species with woody fruits as some plants with succulent fruits are quite fire-resistant, the seeds themselves having a good protective coat. Species of Persoonia provide examples of this. Beadle (1940) quotes figures showing that the number of seedlings which appear on a burned area far exceeds the number on an unburned area, particularly in moist communities, and he brings evidence indicating that the average bushfire does not kill the seeds of many species. He found that a temperature of 110°C. for four hours did not greatly reduce the percentage germination while a few seeds could withstand a temperature of 120°C. or even 130°C. for the same time.
In New South Wales, therefore, natural regeneration after fire is usually quite strong and the structure of the community may not be very greatly altered, especially if the percentage of species exhibiting strong powers of renascence is very high. In most plant communities, however, there is a certain alteration and simplification because of the elimination of non-renascent types. These may become re-established by migration and the original community restored, but where fires are frequent a more or less permanent change may be brought about, as the interval between fires is not sufficiently - long to allow higher phases to develop again. Pidgeon (1938) attributed the compara- tive paucity of species in some localities in the central coastal areas of New South Wales to the effects of repeated fires which resulted in the complete elimination of many species.
Even, however, where there is little apparent change in the composition of the community there is often considerable alteration in the condition of the individual plants, especially trees. Collectively the vegetation on areas which have regenerated after fire may appear quite good, but individually the trees are unsound, especially from a timber-producing point of view. After repeated firing many trees become hollow at the base and may blow over. Fire scars permit the entrance of timber-destroying fungi and insects, and the leading shoots are often destroyed, resulting in distorted growth. Sound straight growing trees become fewer and fewer.
The effects of frequent fires on the physical and other properties of the soil are imperfectly known as regards New South Wales soils, but the general effect is to reduce the amount of humus and to destroy the source of further humus by burning leaf litter. The soil tends to become hard and baked and does not provide good physical conditions for seedlings although the addition of ashes is helpful. Erosion may become more evident as surface run off is increased owing to the hardening of the soil. Useful micro- organisms may be destroyed. On hilly country the effects of forest fires may be especially harmful, as not only is the humus burnt away, but the ash may be washed away by rain. Unless the ash and leaf litter is restored to the soil the growth of trees and shrubs must result in impoverishment, especially in regard to the minor mineral constituents so necessary for plant growth. It might, however, be remembered that, in some parts of the world, soil burning is practised to obtain fertility. It is considered that firing produces a more friable seed bed and one which has been more or less efficiently sterilized. Beadle (1940) states that the Hawkesbury Sandstone soils are not affected to any great extent by fire. He supplies figures showing that fire does not appreciably alter the water-retaining capacity, loss on ignition, or pH value. But these figures show a definite, although slight, alteration in the physical properties of the soil, and it is likely that frequent firing would have an appreciable effect. The Hawkesbury Sandstone soils also, as a rule, have a lower percentage loss on ignition than other soils, and therefore may not be so affected by fire as other types.
An interesting result of fire in forest areas is the reduction of Mistletoe, as in many cases these parasites seem much more susceptible to fire injury than their hosts. After a fire has swept over an area it is quite common to notice how very few Mistletoes survive although the hosts make good recovery. Cleland (1940) records 36 dead Mistle- toes on a tree of Hucalyptus lewcoxrylon which had recovered after a fire.
XX PRESIDENTIAL ADDRESS.
In summing up it might be stated that the more frequent and widely distributed fires following on settlement have caused some modifications of the flora in many districts. These changes, however, are not so great as in other parts of the world owing to the ability of the native species to survive after most fires, or to regenerate success- fully from fire-resistant seeds. The effects of fire are rather imperfectly known and there is abundant opportunity for interesting investigational work. Apart from bush or forest fires there is room for detailed study on the use of fire on pastoral areas, especially as it affects yield, regeneration, soil conditions, and the structure of the plant community. Fire is used fairly commonly in some New South Wales pastures io burn off rank or old growth, the principal objects being to encourage fresh young growth, to provide more uniform grazing, and to permit the better distribution of stock. Little information, however, is available concerning the exact effect of firing on our pastures. It has been suggested that firing results in the elimination or reduction of Medicago species, as the seeds of these cannot survive the fairly great heat developed by some grass fires. In this respect fires may adversely affect grasslands. It is possible that in time they might greatly affect the botanical composition, but whether adversely or beneficially is not known.
Experience in other countries does not help us very much in estimating likely results. Bews (1918) found that continual burning on the eastern grasslands of South Africa had a very marked effect on the composition. Anthistiria imberbis was dominant before firing, but it was gradually replaced by other species, chiefly of Aristida. Experi- ments carried out by Hensel (1923) on Kansas pastures indicated that burnings were not injurious. It was found that burnings did not decrease the number of grass plants and that in the early part of the season there was considerably more grass growth after fire. He showed that both the mean maximum and mean minimum soil temperatures were higher on the burned pastures, and suggests that this might explain the earlier growth of grass. He found, however, that there was a change in the composition of the pastures, one result being a decrease in the number of sedges in the burned area. Australian pastures, however, offer an almost virgin field for this class of research work.
THE INTRODUCTION OF INSECT AND FUNGAL PESTS.
The native plants appear to have been little affected by the introduction of insect and tungal pests. These have caused considerable injury. to the introduced flora, but there is little evidence of them having any noticeable effect on the indigenous plants. A number of introduced species of insects are known to infest some native plants but cause little injury.
Ceroplastes destructor (White Wax Scale) is found on quite a number of native plants, and the related species Ceroplastes rubens (Pink Wax Scale) is not uncommon. In addition a number of species of Coleoptera and Hemiptera, including Aphididae, occur on native plants, but they have little, if any, noticeable effect on the vegetation. None of the introduced fungal pests has any destructive effect on the natural flora, so that it seems correct to say that the native vegetation has remained unaffected to any appre- ciable extent by the fungal and insect pests introduced since settlement.
SPECIFIC USEFULNESS OF INDIGENOUS PLANTS AS A FACTOR IN SURVIVAL AND DISTRIBUTION.
From the early days of settlement the white man found that certain native species supplied some of his needs and were therefore much in demand. The first phase was undisguised exploitation of such plants without any consideration being given to the need for replacement. Early pioneers, for example, found certain timber-producing species most suitable for their requirements. In some cases species like Cedrela australis (Red Cedar) and Araucaria Cunninghamii (Hoop Pine) soon became comparatively rare except in the more inaccessible districts. As supplies became limited attention was given to the conservation of remaining supplies and the establishment of plantations. The general effect of settlement, therefore, was the gradual disappearance of certain species, but as the consequences of this were realized conservation and planting resulted.
The value of native shrubs and trees for, feeding stock, especially during drought periods, was soon appreciated, Here again we notice a gradual disappearance of certain
PRESIDENTIAL ADDRESS. Xxi
species followed by conservation and later by an extension of their range and numbers. For example, Brachychiton populneum (Kurrajong) was soon valued as a very useful fodder and shelter tree. Many trees were sacrificed to ruthless lopping or even felling, but the pastoralist eventually realized that it was to his advantage to conserve supplies. Nowadays this species is widely planted in many parts of the State, and the present effect of settlement is to increase its numbers and to extend it beyond its natural range.
Species with horticultural value, or which are useful for shade and shelter purposes, have secured a wide distribution through planting. Acacia Baileyana, for example, had a very restricted natural distribution, being found only in one or two districts in the south-west of the State. Subsequently, however, it was widely cultivated in many parts of the State, and in quite a number of cases has started to spread naturally from the old planted trees. Acacia podalyraefolia is another wattle which has been cultivated widely because of its attractiveness, and which has become established in some districts. Grevillea robusta and Melia azedarach provide very interesting examples of native species which have extended their range through settlement, although in their case natural regeneration from artificially cultivated trees is seldom seen. Although limited in natural distribution to high rainfall areas of the North Coast and Queensland, where conditions are very favourable for tree growth, they have proved some of the hardiest species for planting in districts of comparatively low rainfall in western New South Wales. Their hardiness under conditions far removed from their natural range is surprising, but is probably due to the fact that they are most sensitive to adverse conditions during - the very early part of their life, and, provided they survive this period, become quite hardy. As this sensitive stage is passed under favourable conditions in the nursery they are able to withstand the less favourable conditions met in later life. One effect of settlement therefore is to extend the range of useful species far beyond their natural habitat.
A similar interesting result of man’s intrusion has been the exploitation of those species which appealed to him because of their floral beauty. Not prepared to admire them only in their natural setting, he felt urged to remove them to adorn his homes and his dwellings. The flower seller harvested his natural crops of native flowers, and all was well until even the unobservant noticed the gradual disappearance of species of Boronia, Telopea, Eriostemon and similarly attractive plants. The advent of motor transport extended the field of exploitation, public interest was stimulated, and eventually the legislature reacted with the Wild Flowers and Native Plants Protection Act. The result of this Act, although difficult to enforce because of inadequate policing facilities, has been to increase the number of plants of protected species in most districts. At least, if not more numerous, they are certainly more noticeable, and there appears to be adequate provision for regeneration. Thus the turn of the wheel passes again through exploitation to conservation.
DISCUSSION.
One hundred and fifty-three years of settlement have produced rather profound changes in the vegetation of New South Wales. The cultivation of crops and the intro- duction of exotic species have resulted, in some cases, in the complete or partial displace- ment of the native flora. The requirements of more concentrated grazing practices in districts of reasonably good rainfall have brought about a conversion of natural grass- lands into pastures consisting almost entirely of introduced plants. But, in areas of low rainfall, the native vegetation still forms the most important part of the pastures and is likely to continue to do so. It seems true that the alien plant makes little headway against the indigenous species in most districts unless favoured by human interference.
Forest lands have been exploited and destroyed, and a forest policy has only begun to emerge from the disturbances created by pioneering settlement. As in the case of most newly settled countries, the utilization of land has been haphazard and based on a short-sighted policy of exploitation. To-day we find that in many districts carrying capacity appears to be declining owing to a deterioration in the grazing material. The results of erosion have become increasingly obvious, and other signs have pointed to the
Xxii PRESIDENTIAL ADDRESS.
unfavourable effects of a disturbed vegetation. But there are indications that we are attempting to do something towards a proper utilization of our land resources. It is becoming more widely realized that the future of Australia is largely dependent on a wise and proper use of her land, and that this in turn necessitates a far more compre- hensive knowledge of our natural flora. It would, of course, be entirely wrong to say that the years since settlement have brought little progress in botanical knowledge. If this were said, a long line of brilliant and indefatigable botanists would turn in their graves with every justification. Considerable taxonomic research has been carried out on the New South Wales vegetation, and we know a great deal about its uses. But two things are necessary. We need to extend our knowledge, and we require that botanical workers, equipped with that knowledge, should play a far more important part in deter- mining the forms of land utilization and in guiding the practices governing primary industries.
Systematic botany has a good record and has produced many able workers, but anyone familiar with the classification of our plants is only too painfully conscious of the many gaps in our knowledge. Ecological research can be said to have only commenced. We know little or nothing about various characteristics of our native species. Our knowledge of root habits, for example, is negligible. We have very few accurate details about reproductive methods and life histories of plants, and have little information concerning capacity to resist grazing. We are confused by variations in palatability in what is regarded as the one species. The erratic behaviour of supposed poisonous plants is a problem only lightly touched upon. In other words the study of our vegetation, in many respects, is only in the preliminary stages. Our knowledge of the results of past settlement indicates the necessity for making such study as complete as possible if land utilization is to have a proper basis. Because my interests lie largely in taxonomic botany, I would emphasize the necessity for a re-awakening of interest in that phase of botanical research, and would stress its importance in a close study of our vegetation. It is true that some workers in systematic botany have suffered from a lack of a proper appreciation of other botanical viewpoints, and have become ‘“‘cribbed, cabined and confined” in the narrow fields of purely herbarium studies. We systematists have sometimes produced species which are merely fictions, useful in some respects, but lacking biological reality. Classification is now regarded as essentially team work, requiring not only the systematist, but the ecologist, geneticist and cytologist. Experi- mental taxonomy is being given increased attention and has great possibilities. The “new systematics” promise us a new heaven and a new earth in which the old-fashioned taxonomist must mend his ways. No doubt we are entering upon a new epoch of changed methods and concepts in classification, and most workers look forward to the future with anticipatory pleasure. At this point, however, my enthusiasm for the new order in systematic botany is checked by one or two practical doubts. I feel rather old fashioned when I admit a conviction that the classification and limitation of species will continue for a long time to be largely based on the classical method of comparative morphology. At all events that basis appears to be the most practical, even if it occasionally produces fictions. Knowing the difficulties involved in obtaining anything approaching completion in the classification of the New South Wales flora, even when based on easily observed morphological differences, I rather fear that classification based on biological team work is a thing of the dim and distant future. It is probable, however, that special groups of plants will receive such treatment. With the development of other branches of botany, especially those involving the stimulating use of experiment, taxonomy has been relegated to the background and given a lower status than it merits. But it seems to me that if we are to get anywhere with a proper study of our native plants we must first put our taxonomic house in order. There can be few developments without the preliminary work of the taxonomist, and we cannot deal. with vegetation reliably or to the best advantage, unless we can first recognize the units of which it is composed. Ecological studies are, of course, extremely necessary and desirable. But in some cases the ecologist is inclined to underrate the importance of knowing his species. He often expresses the opinion that communities are more important than species, and that
PRESIDENTIAL ADDRESS. XXill
ability to recognize all the species in a community is unnecessary in order to make a study of the vegetation. Certainly a limited knowledge of systematic botany does not preclude the student from attacking and solving many problems, but I cannot help feeling that. the ecologist would be a far better ecologist if he had a thorough grip of the species involved. This of course implies close co-operation with the specialist in systematic botany, but there appears to be growing a rather regrettable tendency to underestimate the value of taxonomic knowledge. At times I am troubled by an unworthy suspicion that this represents a very human desire to belittle knowledge, the acquire- ment of which is considered too tedious. My emphasis on the importance of systematics in botanical research, apart from being probably unconvincing, may seem somewhat outside the subject of this address. But, if a study of the effects of settlement upon our vegetation has any lesson for us at all, it is to indicate clearly the necessity for a closer and more detailed examination of our native plants in all their aspects. In this taxonomy must play its fundamental part.
References.
ADAMSON, R. S., and OSBORN, T. G. B., 1924.—Eecology of the Hucaiyptus Forests of the Mount Lofty Ranges, South Australia. Trans. Roy. Soc. S. Aust., xlviii, 87-144.
BEADLE, N. C. W., 1940.—Soil Temperatures during Forest Fires and their Effect on the Survival of Vegetation. J. Hcology, xxviii, 180-92.
Baws, J. W., 1918.—Grasses and Grasslands of South Africa.
BLAKE, S. T., 1938.—The Plant Communities of Western Queensland and their Relationships with Special Reference to the Grazing Industry. Proc. Roy. Soc. Qd., xlix, 156-204.
BREAKWELL, E., 1918.—Weed Seeds and Impurities in Imported Seed. Agric. Gaz. N.S.W., xxix, 633-38.
“CarN, K. G., 1988.—Non-Edible Scrubs. Agric. Gaz. N.S.W., xlix, 124-27.
CLELAND, J. B., 1940.—Rejuvenation of Vegetation After the Bushfires in the National Park, South Australia. S. Aust. Nat., 20, 43-48.
COLLINS, MARJORIE I., 1923.—Studies in the Vegetation of Arid and Semi-arid New South Wales. Part i. The Plant Ecology of the Barrier District. Proc. LINN. Soc. N.S.W., xlviii, 229-66.
—, 1924.—Studies in the Vegetation of Arid and Semi-arid New South Wales. Part ii. The Botanical Features of the Grey Range and its Neighbourhood. Proc. LINN. Soc. N.S.W., xlix, 1-18. i :
DomiIn, Kk., 1911.—Queensland’s Plant Associations. Proc. Roy. Soc. Qd., xxiii, 57-74.
HAMILTON, A. A., 1919.—An Ecological Study of the Saltmarsh Vegetation in the Port Jackson District. Proc. LINN. Soc. N.S.W., xliv, 463-513.
HENSEL, R. L., 1923.—Effect of Burning on Vegetation in Kansas Pastures. J. Agric. Res., 23, 631-42.
Howitt, A. W., 1890.—The Eucalypts of Gippsland. Trans. Roy. Soc. Vict.. ii, 81-120.
JARRETT, PHYLLIS H., and PETRIE, A. H. K., 1929.—The Vegetation of the Blacks’ Spur Region. J. Ecology, xvii, 250-80.
McLuckis£, J., and Petrigz, A. H. K., 1927:—The Vegetation of the Kosciusko Plateau. Proc. LINN. Soc. N.S.W., lii, 187-221.
McTacGart, A, 1939.—The Areas of Australia in which the Hstablishment of Exotic Plants is, or appears to be, Practicable. J. Cowne. Sci. Industr. Res., Melbourne, 12, 151-54.
Moopign, A. W. S., 1934.—Red Grass. Agric. Gaz. N.S.W., xlv, 601-3, 680-84.
————, 1940.—Grassland Improvement in N.S.W. J. Aust. Inst. Agric. Sci., 6, 85-90.
Morris, MARGARET V., 1939.—Plant Regeneration in the Broken Hill District. Aust. J. Sci., ii, 43-48.
NicHo.us, J. E., 1938.—Investigations on the Pastoral Areas in Western Australia. J. Aust. Inst. Agric. Sci., 4, 10-17.
OsBorn, T. G. B., 1928.—The Biological Factor in the Study of Vegetation. Rept. Aust. Ass. Adv. Sci., xix, 611-26.
, Wood, J. G., and Paltridge, T. B., 1935.—On the Climate and Vegetation of the
Koonamore Vegetation Reserve to 1931. Proc. LINN. Soc. N.S.W., Ix, 392-427.
Peacock, R. W., 1908.—Rabbits and the Western Flora. Agric. Gaz. N.S.W., xix, 46-48.
PIDGEON, I~MA M., 1938.—The Ecology of the Central Coastal Area of New South Wales. Proc. LinN. Soc. N.S.W., Ixiii, 1-26.
, and Ashby, E., 1940.—Studies in Applied Ecology. i. A Statistical Analysis of Regeneration following Protection from Grazing. Proc. Linn. Soc. N.S.W., Ixv, 123-43. WapDHAM, S. M., and Woop, G. L., 1939.—Land Utilization in Australia. Melbourne University
Press.
XXIV PRESIDENTIAL ADDRESS.
Dr. G. A. Waterhouse, the Honorary Treasurer, presented the balance-sheets for the year ended 28th February, 1941, duly signed by the Auditor, Mr. S. J. Rayment, A.C.A. (Aust.); and he moved that they be received and adopted, which was carried
unanimously.
No nominations of other candidates having been received, the Chairman declared the following elections for the ensuing session to be duly made: President: A. B. Walkom, D.Sc. Members of Council: E. C. Andrews, B.A., Ida A. Brown, D.Sec., W. R. Browne, D.Se., Professor J. M. Holmes, B.Se., Ph.D., F. H. Taylor, F.R.E.S., F.Z.S., A. B. Walkom, D.Sc. Auditor: S. J. Rayment, A.C.A. (Aust.).
The retiring President, on behalf of members, then made a presentation to Dr. A. B. Walkom in appreciation of his long service with the Society as Secretary.
A cordial vote of thanks to the retiring President was carried by acclamation.
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XXVili ABSTRACT OF PROCEEDINGS.
ABSTRACT OF PROCEEDINGS.
ORDINARY MONTHLY MEETING. 26th Marcu, 1941. Dr. A. B. Walkom, President, in the Chair.
The Donations and Exchanges received since the previous Monthly Meeting (27th November, 1940), amounting to 16 Volumes, 319 Parts or Numbers, 15 Bulletins, 10 Reports and 16 Pamphlets, received from 102 Societies and Institutions and 3 private donors, were laid upon the table.
PAPERS READ.
1. Plant Ecology of the Bulli District. ii. Plant Communities of the Plateau and Scarp. By Consett Davis, M.Sc.
2. Plant Ecology of the Bulli District. iii. Plant Communities of the Coastal Slopes and Plain. By Consett Davis, M.Sc.
3. A Summary of certain Aspects of the Scarab Problem, and a Contribution to a Bibliography of the Family Scarabaeidae. By D. Margaret Cumpston, M.Sc.
ORDINARY MONTHLY MERTING. 30th Aprin, 1941, Dr. A. B. Walkom, President, in the Chair.
The President announced that the Council had elected Mr. E. C. Andrews, Mr, T. C. Roughley, Professor J. Macdonald Holmes and Mr. R. H. Anderson to be Vice-Presidents for the Session 1941-42.
The President also announced that the Council had elected Dr. G. A. Waterhouse to be Honorary Treasurer for the Session 1941-42.
The President, on behalf of members, expressed congratulations to Professor W. N. Benson on his election as a Fellow of the Royal Society of London.
The Donations and Exchanges received since the previous Monthly Meeting (26th March, 1941), amounting to 18 Volumes, 120 Parts or Numbers, 4 Bulletins, 3 Reports and 3 Pamphlets, received from 59 Societies and Institutions, were laid upon the table.
PAPERS READ.
1. Notes on Australian Diptera. xxxix. Family Chloropidae. Part iii. By John R. Malloch. (Communicated by F. H. Taylor, F.R.E.S., F.Z.8.)
2. A Survey of the Mistletoe of New South Wales. By Valerie May, M.Sc. 3. Studies on Corticium rolfsii (Sace.) Curzi. By F. L, Milthorpe, B.Sc.Agr.
PLANT ECOLOGY OF THE BULLI DISTRICT. PART Il: PLANT COMMUNITIES OF THE PLATEAU AND SCARP. By Consetr Davis, M.Sec., Lecturer in Biology, New England University College. (Plates i-ii; one Text-figure.)
[MS. received 9th February, 1940.* Read 26th March, 1941.]
Foreword.
Unavoidably, a considerable period has elapsed between the appearance of Part i of this series (Davis, 1936) and the completion, for publication, of the remaining parts. During the interval, several important papers have appeared, dealing with the plant ecology of the New South Wales coastal region (Pidgeon, 1937, 1938; Fraser and Vickery, 1987, 1988, 1939; Osborn and Robertson, 1939). With reference to the classification of the Hucalyptus forest communities submitted in Part i, some further clarification is now necessary.
Pidgeon (1937) has advanced a classification of the Hucalyptus forests of the central coastal area of New South Wales, recognizing six associations in the entire region, with subordinate consociations, and giving much broader limits to the association unit than those adopted in Part i of this series. While it is freely admitted that this broader limitation for the association is in accordance with the application of North American workers, and that certain of the ‘associations’ listed in Part i of this series will in time take their place as ‘consociations’ within broad association limits, it is submitted that insufficient is known of the environmental, genetic and phylogenetic relations of the various Hucalyptus forest communities safely to dogmatize on the natural grouping of consociations at the present stage. If the association be regarded as generic, and the consociation as specific, the procedure adopted in Part i represents the erection of a number of monotypic genera, whereby, admittedly, natural relationships cannot be indicated; the alternative procedure, however, runs the risk of erecting genera including unrelated species.
The following table sets out the differences in the two classifications:
Situation of Community. Classification of Part 1. Classification of Pidgeon (1937). Hawkesbury Sandstone, little or Eucalyptus Sieberiana Mixed Hucalyptus Forest Asso- no physiographic shelter. Association. ciation. Do., moderate physiographic E. piperita Association. Do. shelter. Do., good physiographic shelter. E. pilularis Association. Do. Narrabeen Sandstone, little or E. piperita Association. Do. no physiographic shelter. Do., moderate physiographic EF. saligna Association ; ? H. saligna-EH. pilularis Associa- shelter ; Chocolate Shale, little E. pilularis Association tion. or no physiographic shelter. (upper coastal slopes).
* Note added 23rd September, 1940.—An important paper on plant succession by Pidgeon (Proc. Linn. Soc. N.S.W., Ixv, 221-249; issued 16th September, 1940) deals with the general aspects of the area of which the Bulli district forms merely a unit. Circumstances forbid the modification of the present two papers (Plant Ecology of the Bulli District. ii and iii) in the light of knowledge therein presented, or any discussion of points raised. Nevertheless, although much of the ground has been covered, it is still considered worth while to present these two papers in their original form, both as independent (though local and less complete) evidence of certain facts and as maintaining a somewhat different viewpoint on controversial issues.
D
2 PLANT ECOLOGY OF THE BULLI DISTRICT. MII,
Situation of Community. Classification of Part i. Classification of Pidgeon (1937). Wianamatta Shale, little or no E. piperita - Angophora Mixed Hucalyptus Forest Asso- physiographic shelter. lanceolata Association. ciation. Upper Coal Measures (shales J£. pilularis Association. E. saligna-E. pilularis Associa- and sandstones), little or no tion.
physiographic shelter.
Upper Coal Measures (tufface- Mixed Hucalyptus Forest. Mixed Bucalyptus Forest Asso- ous mudstone), little or no (a). ciation. physiographic shelter.
Recent Alluvial Soil, little or no Mixed Hucalyptus Forest. Do. physiographic shelter (climax (Db). of lagoon succession).
The separation, in Part i, of the ‘Hucalyptus piperita-Angophora lanceolata Association’ from the normal EH. piperita Association is not justified, and the former is henceforth referred to as the Angophora lanceolata facies of the Hucalyptus piperita Association.
Pidgeon’s grouping of the Hucalyptus saligna and #H. pilularis communities as a single association is probably justified. In Part i the relationship was marked by referring to the communities as corresponding associations (p. 295). The tendency of £. saligna to predominate at the ecotone of the H#. pilularis Association and the rain forest formation on the coastal slopes suggests that it requires better environmental conditions than #. pilularis. The distinction of the two associations is tentatively retained in this and subsequent parts for uniformity with the smaller sense of ‘association’ used throughout.
Pidgeon’s separation of the Hucalyptus pilularis Community into two associations depending on soil origin (on Hawkesbury Sandstone, Mixed Hucalyptus Forest Association, pars; on richer soils, consociation of H. saligna-H. pilularis Association) seems to add to the complexity of the classification. The community on Hawkesbury Sandstone is closely similar to its manifestations elsewhere, both in the form and height of the dominant tree, and also in the presence of certain species of the lower strata (e.g., Casuarina torulosa, Leucopogon lanceolatus, Pteridium aquilinum, Imperata cylindrica var. koenigti, Hardenbergia monophylla) which are characteristic of the E. pilularis Community on Upper Coal Measures soils, but absent from poorer sandstone soils, such as in the #. Sieberiana Association. Even the soil properties are similar, due to the improvement of the water-retaining capacity of sandstone soils carrying E. pilularis, by humus accumulation, up to a point comparable with that of soils derived from less coarsely-grained rocks.
The Hucalyptus Sieberiana Association is a widespread and important unit, which scarcely appears in its typical form north of the Bulli district. It is extensively developed on soils derived from Devonian sandstones on the far south coast of New South Wales, particularly in the Eden district. It also occurs in Victoria and Tasmania, where it assumes the appearance of a wet sclerophyll forest, regarded by some workers as a distinct formation or sub-formation (Wood, 1937), although the distinction is arbitrary. North of the Bulli district other species (e.g., H. gummifera, H. haemastoma) occupy more important places on correspondingly poor soils, although £. Sieberiana extends north as far as the Hawkesbury River.
The separation of the communities dominated by Eucalyptus piperita from the E. Sieberiana Association appears to be justified, in order to emphasize the fact that E. piperita represents a definite grade higher than #. Sieberiana in soil requirements, just as HL. pilularis represents a grade above E. piperita. This gradation tends to be obscured by grouping together under the one unit, as the Mixed Hucalyptus Forest Association of Pidgeon. It could be equally emphasized by calling the grades consociations (as allowed by Pidgeon, 1937, p. 335), but it would be difficult to group three such consociations into an association without harming other parts of the
classification system, e.g., the recognition of the Z. pilularis unit on all soil types, discussed above.
BY CONSETT DAVIS. 3
The classification of Part i is therefore retained throughout the series, with the exception of the EH. piperita-Angophora lanceolata Association noted above. The classification has sufficient utility for the limited district here dealt with, although it would be difficult to apply it, even with logical extensions, throughout the entire sclerophyll formation of eastern Australia. This difficulty need not be met in the present series, which is purely local in nature; it is hoped that some synthesis of the different classifications will develop when the entire formation comes to be considered. It is further emphasized that the divergence from the classification of Pidgeon does not indicate a divergence in the observance of facts, but merely in opinion as to convenience of tabulation.
Nomenclature.
In general, the same procedure in taxonomic names is followed as in Part i, authors’ names being appended to species only where the names given by Moore and Betche (18938) are not adhered to. For Pteridophytes the names given by Melvaine (1936) are used throughout, without authors. Many of the names used by Moore and Betche have now been superseded, but this work is nevertheless the only flora available to field workers. In a few cases the names used in Part i have been changed in this and subsequent parts for uniformity with the ecological papers mentioned above. The following are the changes:
Eucalyptus gummifera (Gaertn.) Hochr. (E£. corymbosa of Part i); Imperata cylindrica Stapf. var. koenigiti D. & S. (1. arundinacea of Part i); the generic name Lomandra is henceforth used in place of Xerotes. The name Gymnoschoenus sphaero- cephalus (R.Br.) Hook. f., as used in Part i, is retained; this is apparently the correct name (see, e.g., Black, 1929, p. 91), although the species is listed by Moore and Betche as Schoenus sphaerocephalus Poir. (syn. Mesomelaena sphaerocephala Benth.), and by the Census (Maiden and Betche, 1916) as Gymnoschoenus adustus Nees.
METHODS.
(i). Soil Analyses.—A large number of soil samples were tested for various properties, and since the methods used, though constant throughout, were not the usual standard methods, they are detailed fully. The figures are strictly comparable inter se, but not necessarily with those given by other workers.
Except for pH and water content, all samples were passed through a sieve with circular holes of diameter 1 mm. The pH was determined by the quinhydrone method (gold electrcde), standard procedure being adopted to eliminate the vitiation of the results for comparative purposes by drift. Soils were stirred with distilled water and quinhydrone, stood for 45 minutes, and again stirred. At the end of a further 15 minutes the E.M.F. was read without further stirring.
To estimate comparative water content the soils from a series were collected at the same time in sealed jars, and samples weighed as soon as possible. These were then dried at 90-100°C., the water content being calculated as a percentage of the dry weight.
The method of determining water-retaining capacity gives a higher reading than the methods usually adopted. Metal cylinders (height 2-5 cm.; diameter 5 cm.) with gauze bottoms were lined with filter-paper, cut to cover the bottom but to allow drainage at the periphery, since drainage through the filter-paper becomes impeded by clay particles. The lined cylinders were weighed dry (m,) and wet (m,). They were then filled with saturated soil, drained for 30 minutes, and weighed (m,). The whole was then dried to constant weight (m,) at 90-100°C. The water-retaining capacity is calculated
m,;-m,— (m,-m, ) ; 3 thus: ———————————- . 100, representing a percentage of the dry weight. The usual m,-M,
method of weighing soil dry, and allowing it to take up water, proved impracticable, as dry soils, especially sandy soils with high organic content, could not be caused to take up water without loss of part of the sample from the container. The high temperature of drying (90-100°C.) in the method used was essential from considerations of time; but it renders the final figure for water-retaining capacity high by including in it some water not available to plant roots.
4 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
Loss on ignition, of soils previously dried at 110°C., expressed as a percentage of the dry weight, gives a reasonably close approximation to the total organic content (humified and unhumified). Exceptions are soils of high clay content (especially Wianamatta Shale soils, and to a less extent soils from Chocolate Shale and some of the Upper Coal Measures), and the early stages of the sand-dune succession described in Part iii, where a fair proportion of calcium carbonate is present.
In representative samples the portion of the figures for loss on ignition, represented by humus, was estimated by determining the percentage of the original soil decomposed to gaseous and volatile substances by continued treatment with hot 6% hydrogen peroxide.
The chloride contents (listed in Part iii) were obtained by lixiviating a known weight of oven-dry soil with distilled water, and estimating the filtrate with standard silver nitrate. The chloride contents are expressed as a percentage weight of chlorine (chloride ion) per dry weight of soil. This figure is undoubtedly variable for any situation, due to seasonal factors of spray incidence and leaching. All the figures given refer to soils collected in July 1938, a period preceded by some time of low rainfall and little leaching. Figures for salinity of soil solution, as sodium chloride, grm. per litre (Lagatu and Sicard, 1911), depending on the water-content of the soil, may be caleulated from the data of Table 4, Part iii. This factor, although it is at any one time a truer index of the conditions to which plant roots are subjected, must be exceedingly variable for any situation, due to seasonally varying soil moisture.
For all the above factors, soils of the A, horizon (1—4 inches), the zone of maximum utilization by plant roots, have been determined.
Percentage of water held at sticky-point and sand fraction were estimated for soils of varying origin. From these results the index of texture (Hardy, 1928) was calculated (percentage of water held at sticky-point less one-fifth percentage of sand). The samples used for this work were from the A, horizon, as in the A, horizon varying organic content would affect the water held at sticky-point; whereas the property, the investigation of which is here desired, is that of the original soil as conditioned by parent rock, and not the soil resulting from the interaction of vegetation with original soil.
The index of texture actually appears to be a less useful index of the soil with respect to vegetation than is the percentage of water held at sticky-point alone. The index of texture suffers further in that no distinction is made in its calculation between coarse and fine sand, both lowering the index of texture figure equally. Thus almost all the sand fraction of Hawkesbury Sandstone soils is coarse sand, and almost all that of Chocolate Shale soils is fine sand, the latter with a greater capacity to hold water in the estimation at sticky-point.
(ii). Floristics—Only in the relatively homogeneous Gymnoschoenus sphaero- cephalus Community (swamp subclimax on Hawkesbury Sandstone) were accurate quadrats undertaken. These took the form of metre-quadrats, each shoot of the rhizomatous vegetation being removed by shears and counted as one unit. This procedure was necessitated by the density of the vegetation (Pl. ii, C).
In the lower strata of the remaining communities, and in the tree stratum of the brush or rain-forest, rough counts of the numbers of each species in a series of areas were made. These areas were circles of 10 yard radius or, for brush trees, 20 yard radius. For each community, the number of individuals of each species was multiplied by the factor necessary to bring the commonest species to 100 units. The species were then graded into five classes: abundant (A), 100-41; common (C), 40-16; occasional (O), 15-6; rare (R), 5-3; and very rare (VR), 2 or less. These limits were chosen in consideration of the lack of complete domination by one species of the strata examined; it is clear that a species occurring in a ratio of 1:25 to the commonest species would not be rare, in the accepted sense, if the commonest species practically dominated the
community; but in the communities examined co-dominance of a number of species was the rule.
BY CONSETT DAVIS. 5
Some modification of the results obtained was found necessary, due to the accumulation of additional data by inspection, without analysis, of certain areas not visited when the counts were made. This applies especially to the Hawkesbury Sandstone shrubs. The classes are therefore only approximate, but probably closer to the truth than a gradation by inspection alone could attain.
The proportion of the counts in which each species appeared gave some indication as to localization, and in the floristic lists species are tabulated as local (L) if this feature is particularly marked.
PLANT COMMUNITIES OF THE PLATEAU AND SCARP. (1) Hawkesbury Sandstone.
-(a). Eucalyptus Sieberiana Association.
This community (Pl. i, A and B), present in situations on the Hawkesbury Sand- stone lacking physiographic shelter, is usually associated with fairly efficient drainage conditions, although the dominant occasionally approaches positions of fairly high water-table near the ecotone with swamp communities. Soils are typically of a depth greater than three feet, often much more, but in some places the association occurs on shallower soils, the dominant then being dwarfed and often malformed. These areas may be regarded as a stage in the lithosere, detailed later, immediately preceding the true climax.
Soil properties for certain typical parts of the association are given in Table 1. The texture of the soil originating from Hawkesbury Sandstone is coarse, although the weathering of local shale bands in this series gives a small but definite clay fraction in some places, and in particular gives the B horizon in most places the nature of a elay-sand. The following estimates were obtained for A. soils:
Water held at sticky-point 22-29%; sand fraction 96-97%; index of texture 3-10.
The uniformly low organic content is insufficient to counteract the coarseness of the soil, and the water-retaining capacity is low. The highest figure for water-retaining capacity (37%) represents a sample with higher clay-content than normal. Of the figures given for loss on ignition (2:3-3:5%), some 50% appears to represent humus. The soils are markedly acid, and appear to be poor in nutrient elements.
TABLE. 1. Properties of Soils on Hawkesbury Sandstone carrying Climax and Post-climax Communities.
W.R.C. Loss on Jgnition pH. ar (%). (%).- Eucalyptus Sieberiana Association ake aay ae ab 25 P2015) 5-4 29 372 4-9 28 3:0 4-9 29 2-9 5-2 37 P3083 4-5 33 Bobs) 4-9 Eucalyptus piperita Association. . 43 he 5-2 46 8-0 4-4 49 8:7 4:6 78 26-0 4-9 83 30-0 4-7 76 23-0 5-1 Eucalyptus pilularis Association 80 23-0 5-0 91 3: 5-0 Eucalyptus piperita Association, near Brush Ecotone (Loddon Falls) .. ay bie ok ae af a ne 113 49-0 4-6 Brush oe He ae ah ne ite ae ov 90 30-0 5:2 120 35-0 5:2 120 49-0 53 130 48-0 5:0
6 PLANT ECOLOGY OF THE BULLI DISTRICT. ILI,
Some indication of the range of the dominant has been given earlier. A consideration of its environment elsewhere suggests that neither poor drainage nor shallowness of soil is one of the limiting factors here preventing the development of species such as Eucalyptus piperita and E. pilularis. These factors are rather to be sought in the coarseness of the soil texture, and the resulting low water-retaining capacity in the absence of humus development.
Structurally the association is composed of a tree stratum typically 40-60 feet high, with discontinuous canopy. Low trees are relatively unimportant, Banksia serrata being common only in limited areas; some of the larger shrubs, however, fall within the microphanerophyte class. The shrub stratum is prominent and floristically diverse, though usually not continuous. The ground stratum seldom forms a complete cover, except in areas tending towards swamp conditions. The classification into life-forms is indicated in the floristic lists.
Floristically, the composition of the association is as follows:
MM:* A, Eucalyptus Sieberiana (dominant); O(LC), H. gummifera, E. micrantha Benth. ; VR(L), Casuarina suberosa, Acacia elata.
M: LC, Banksia serrata (Shrubs); C, Leptospermum stellatum, L. flavescens, Banksia ericifolia; O, Hakea acicularis; VR(L), Kunzea corifolia. N: A, Grevillea oleoides, Hakea dactyloides, H. pugioniformis, Isopogon anemonifolius,
Lambertia formosa, Persoonia lanceolata, P. salicina, Petrophila pulchella, Leptomeria acida, Olax stricta, Acacia discolor, A. juwiiperina, A. suaveolens, Aotus villosa, Bossiaea heterophylla, B. scolopendria, Dillwynia floribunda, Pultenaea elliptica, Ricinocarpus pinifolius, Pimelea linifolia, Leptospermum scopariuwm, EHpacris microphylla, EH. obtusifolia, Leucopogon juniperinus, L. microphyllus, Sprengelia incarnata, Dampiera stricta; C, Banksia spinulosa, Conospermum ellipticum, C. taxifoliwm, Grevillea sericea, G. punicea, Lomatia silaifolia, Acacia myrtifolia, Gompholobium latifolium, Comesperma ericinum, Baeckea crenulata, B. linifolia, Kunzea capitata, Trachymene linearis, Epacris paludosa; O, Sympho- nema paludosum, Xylomelum pyriforme, Daviesia wulicina, Gompholobium grandi- florum, Hriostemon Crowei, Phebalium diosmewm Juss., Dodonaea triquetra, Stackhousia viminea, Callistemon lanceolatus, Calythrix tetragona, Darwinia virgata, Leucopogon collinus, Woolsia pungens, Hemigenia purpurea; R, Banksia paludosa R.Br., Telopea speciosissima, Phyllota phylicoides, Boronia pinnata, Lasiopetalum ferrugineum, Epacris longiflora, Leucopogon virgatus, Chloanthes Stoechadis; VR, Banksia aemula, Grevillea sphacelata, Cryptandra ericifolia, Melaleuca squamea, Leucopogon amplexicaulis, \L. esquamatus, Dampiera Brownii.
Ch: A, Lomandra obliqua MacBride, Patersonia glauca; C, Doryanthes excelsa, Mirbelia reticulata, Tetratheca ericifolia, Ampera spartioides, Hibbertia stricta, Stylidiwm graminifolium Swartz; O, Xanthorrhoea hastilis, Patersonia sericea. Conospermum tenuifolium, Grevillea capitellata, Darwinia taxifolia, Xanthosia pilosa, Opercularia ovata, Pomax wmbellata, Lobelia dentata; R, Gompholobiwm minus, Hovea hetero- phylla, Hybanthus filiformis, Viola hederacea, Styphelia triflora, Goodenia heterophylla; VR, Kennedya prostrata, Comesperma volubile.
Inb¢ A, Haemodorum planifolium, Actinotus minor; LC, Selaginella uliginosa; O, Gahnia psittacorum, Lomandra longifolia Labill., L. filiformis J. Britten; R, Hragrostis Brownii, Stipa pubescens, Caustis flexuosa, ‘Tricostularia paludosa Benth., Haemodorum teretifoliwum; VR, Entolasia marginata Hughes, Caustis pentandra, Stypandra caespitosa, Rubus fruticosus (introd.).
G: A, Leptocarpus tenax, Lepyrodia scariosa; O, Thelymitra ixioides; VR, Burchardia umbellata, Cryptostylis longifolia, Glossodia major. BH: O, Cassytha paniculata, C. pubescens;+ VR, Loranthus celastroides.t
The above lists include some species (e.g., Symphyonema paludosum, Olax stricta, Baeckea spp.) which are more characteristic of swampy areas, and others (e.g., Lepto- carpus tenax, Lepyrodia scariosa) which occur in this association and in swamps in approximately equal frequencies. The frequency given above in all cases represents
* Abbreviations for life-forms, frequency, and localization used throughout paper: MM, mega- and mesophanerophytes; M, microphanerophytes; N, manophanerophytes; Ch, chamaephytes; H, hemicryptophytes; G, geophytes; HH, helo- and hydrophytes; S, stem- succulents; BE, epiphytes. (Actually, no hydrophytes are present in the species listed under HH.) A, abundant; C, common; O, occasional; R, rare; VR, very rare; L, local or locally; LC, locally commion (see METHODS, Floristics).
7 Rooted hemiparasites, classed as ‘‘H’’, the nearest life-form.
i In these lists the species are arranged in order of families according to the classification of Engler and Prantl, and within each family, alphabetical.
BY CONSETT DAVIS. 1
that observed in the Hucalyptus Sieberiana Association, regardless of the frequency of the species elsewhere; it has been noted earlier that this association extends in some cases to rather poorly-drained soils.
Apart from minor environmental variations, such as in efficiency of drainage, with their resultant influences, e.g., on the proportion of swamp-tolerant species, the association is characterized by local variations, often striking, without apparent environ- mental cause. These variations are most marked in the shrub stratum; they may well be due to chance occurrences in seed dispersal, and to the extinction of some species in belts where bush-fires of preceding years have been most severe.
Two environmental variants were noted in Part i:
(1). On the eastern edge of the plateau, particularly north of Sublime Point, on the gradual slope running down towards the sandstone scarp (Fig. 1), the vegetation assumes ‘an aspect slightly different from other parts of the plateau. Drainage conditions are good, so that species favoured by swampy conditions are absent. Hucalyptus gummifera increases in abundance, often becoming nearly as important as H. Sieberiana; both species are frequently stunted, as the soil is often very shallow. In most places the cover by the lower strata increases, often to 100%. Additional species found in this zone, but not elsewhere in the association, include:
N: Xanthorrhoea arborea R.Br., Hakea saligna, Persoonia revoluta, Pultenaea daphnoides,
Correa speciosa, Actinotus Helianthi, Dracophyllum secundum, Cassinia denticulata, Olearia elliptica DC.
N (climbers): Smilax glycyphylla, Billardiera scandens.
Ch: Dianella coerulea, Halorrhagis teucrioides, Helichrysum scorpioides.
G: Lycopodium densum, Gleichenia flabellata.
Certain species found elsewhere in the association increase in prominence; the following may be specified:
N: Banksia spinulosa, Boronia pinnata, Phebalium diosmeum Juss., Lasiopetalum
ferrugineum, Epacris longiflora, Chloanthes Stoechadis.
Ch: Xanthosia pilosa, Opercularia ovata.
The factor inducing this variation seems to be the shelter from the west, which, while too slight to affect the trees, allows certain more mesophytic types to develop in the lower strata. The soil differs little, if at all, from that in other parts of the association. Certain species cannot be considered more mesophytic than those of other areas; such forms as Xanthorrhoea arborea and Actinotus Helianthi, occurring only at the very edge of the plateau, are to be considered rather as species limited to very dry, rocky habitats.
(2). The slopes facing west, in the more westerly parts of the area studied, are characterized by better drainage and lower rainfall than the flatter areas of the eastern parts of the plateau (cf. Parti). Hucalyptus gummifera increases in relative abundance; in the lower strata there are a decrease in percentage cover and a general absence of swamp-tolerant species.*
The Hucalyptus Sieberiana Association is in general similar to much of the low forest on sandstone in the Sydney district, although its dominant fails to reach such development near Sydney either in size or frequency. The lower strata are somewhat poorer floristically than in corresponding situations near Sydney, and possess very few additional species (e.g., Grevillea oleoides).
(0). Developments subject to Physiographic Shelter.
With increasing physiographic shelter, Hawkesbury Sandstone soils carry successively higher types of vegetation, the sequence being Hucalyptus piperita Association-H. pilularis Association-Brush (sub-tropical rain-forest) (Pl. i, C, D, E respectively). The characteristics of the soils of this series are listed in Tables 1 and 2. The series is characterized by a successive rise in organic content of the soil, proportionally raising the water-retaining capacity, which appears to be the chief factor influencing the development of the first two associations. The addition of a higher
* The occurrence of some well-developed trees of Syncarpia laurifolia Ten. near the Bulli
Lookout, intermingled with #. Sieberiana in an otherwise normal part of the association, is absolutely unexplained. Syncarpia is a unit of a much higher vegetational community.
8 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
TABLE 2.
Hawkesbury Sandstone Soils on Transect with Increasing Shelter.
Loss on Water Content - W.R.C. Ignition pH. (69%) (%). (%)- (10.7.38). Eucalyptus Sieberiana Association fe 37 203 4-5 1-9 E. piperita Association ae i FAS 46 8-0 4-4 8-2 E. pilularis Association 80 23-0 5-0 12-9
proportion of humus* to a soil of coarse texture raises the water-retaining capacity to the level of finer soils with less humus, such as carry these associations on the other geological series of the district.
The rise in organic content seems to be associated chiefly with a high average moisture-content, a result of drainage conditions and weak insolation, depending on the physiography. It is not comparable with the rise of organic content under swampy conditions, to which are limited plants tolerant to low pH and poor root aeration. Apart from moisture-content, other factors inducing a high organic content in this series are decreased insolation and infrequency of bush-fires, both factors directly combating oxidation of soil humus. The infrequency of bush-fires is dependent on the relatively moist nature of the habitat and vegetation.
In no case studied could the full vegetational sequence be observed on a single transect. In the more gradual valleys south of Cataract Reservoir, Hucalyptus Sieberiana gives place to H. piperita (on the upper slopes) and WH. pilularis (on the lower slopes and valiey floor); shelter is throughout insufficient for brush, which however develops where erosion has led to the penetration of the Narrabeen beds at the bottom of some gullies. In the abrupt Hawkesbury Sandstone gorge at Loddon Falls, brush is developed at the lower levels; on the steep sides, Hucalyptus piperita occurs. EH. pilularis does not
* Humus accounts for approximately half of the loss-on-ignition figures of Tables 1 and 2.
rus micrantha
andslone shrubs
¢ ise ea WL ——_——_— SOUL SUT CO COGS -OS~S 0-005
rs i eae Ud glu ceiletabscue pueda F/n pi ORDO at Seta Ljunipermum Gymnosch® ere ENCES Uae ie ; eZ aa) oe af soil surfoce ov | ee %, ee | Properties [Loss on ignition lo Cnorock at i7 ft debh } Peete pie ==, 1c
sur face H 5:0 : oie Wie contenl 14.7.38 83%
Fig. 1.—Section west of Hawkesbury Sandstone scarp, about half a mile north o average water-tablew}
BY CONSETT DAVIS. 9
develop, the ecotone between the Hucalyptus piperita Association and the brush formation, where soil conditions are suitable for H. pilularis, is very narrow, due to the steepness of the slope. Brush is developed to a limited extent in several ravines in the Hawkesbury Sandstone scarp at the eastern limit of the plateau; Hucalyptus piperita and. E. pilularis do not develop here as intermediates, the belt between EH. Sieberiana (on the edge of the plateau) and the brush (in the floor of the ravine) constituting the rocky shoulders of the ravine, almost devoid of soil.
The limitation of brush to the lower parts of the Loddon Falls gorge and to the scarp ravines, together with a general consideration of brush development in the Bulli district as a whole, suggests that this formation is conditioned primarily by shelter from wind and sun, secondarily only by soil requirements. The assumption that Hucalyptus piperita and H. pilularis are conditioned by soil alone, and not by wind and sun, is based on the fact that their canopies are fully exposed in most situations studied on Hawkesbury Sandstone as on other soils.
Additional elements of the Hucalyptus piperita and EH. pilularis Associations on the Hawkesbury Sandstone include the mesophanerophyte, Casuarina torulosa (second association only), and the microphanerophytes, Hakea saligna, Persoonia linearis, Hxocarpus cupressiformis, Acacia longifolia, A. mollissima and Hlaeocarpus reticulatus; the nanophanerophytes, Trachymene Billardieri and Leucopogon lanceolatus; the chamaephytes, Hibbertia Billardieri and Hardenbergia monophylla, and the geophyte Pteridium aquilinum. These are absent from the H. Sieberiana Association. There are also present species found in the H. Sieberiana Association only at the extreme east of the plateau (e.g., Smilax glycyphylla, Pultenaea daphnoides, Halorrhagis teucrioides and Cassinia denticulata), and species of the normal H. Sieberiana Association (e.g., Banksia spinulosa, Persoonia salicina, Lasiopetalum ferrugineum and Dodonaea triquetra), sometimes increased in frequency compared to the #. Sieberiana Association (e.g., Hntolasia marginata Hughes and Viola hederacea).
The high and low trees are characteristic of the Hucalyptus piperita and H. pilularis associations on other geological formations, the Eucalypts in some cases reaching nearly 100 feet in height. The lower strata include many of the same species as are found in these associations on other geological series, but are structurally different,
} 5 Sieberja Alsi fang
Oe ee irre a Vg
ubs
| gana sfone ales
soil sur fact : 5
| ae
of aot ee eee
100 yards
is height and composition of vegetation, outline of soil surface, soil properties, tour of rock surface.
10 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
especially in the lower percentage cover. This latter is partly due to the fact that Hawkesbury Sandstone situations carrying these associations (sloping valley sides) have a fairly high percentage of exposed rock.
Brush, as developed at Loddon Falls (Pl. i, E), has a structure more or less typical of this formation on other geological series (closed canopy, absence of shrubs, presence of a ground layer of ferns), but is very poor floristically:
MM: Doryphora Sassafras, Cryptocarya glaucescens, Callicoma serratifolia, Pittosporum undulatum, BHueryphia Moorei, Tristania laurina.
M: Drimys insipida Druce, Tristania neriifolia.
Che Todea barbara.
IBis Adiantum diaphanum, Asplenium flabellifolium.
B: Davallia pyxidata, Pleopeltis diversifolia, Tmesipteris tannensis.
(Epiphytes, also growing on rock surfaces.)
The only common tree amongst these, which is characteristically a brush type (as opposed to a member of the ‘wet gully’ or creek-edge flora), is Doryphora Sassafras. Callicoma and Pittosporum, though often occurring in true brush, also extend to the ‘wet gully’ flora, a brush-sclerophyll ecotone community, while the species of Tristania commonly occur beside rocky creeks, often with little shelter from wind and sun.
(c). Lithoseres.
It is impossible adequately to account for rock succession or zonation without first considering the past history and present course of the physiographic development of the area studied. The sandstone plateau, part of the Nepean Ramp, is an example of rejuvenated physiography, representing a late Tertiary peneplain raised by Pleistocene uplift.* As such, its exposed rock surfaces are mostly manifestations of a highly immature topography. To this extent, the postclimax communities detailed in the preceding section may be considered expressions of a purely allogenic succession.
On the evidence of the physiographic facts cited above, zonations between bare rock and forest, except possibly in the case of certain of the moist lithoseres detailed later, are, on the average, retrogressive, though many simulate temporal succession, and in some cases exposure of a new rock surface by physiographic change (falls of rock, or scouring of soil into a relatively recently-formed gully) may be followed by colonization and true succession up to a certain stage, that is, up to a time when denuding factors once again come into play. In spite of general retrogression, it is convenient to regard the zonation stages from rock to forest as a lithosere, whilst remembering that allogenic factors prevent true succession to a climax under the average conditions of the area. The ultimate peneplanation of the area, in the processes of which plant life undoubtedly plays a part (e.g., in rock decomposition), is too distant to visualize in terms of the present flora.
Bare rock surfaces, leading by a vegetational zonation of xeric communities to forest, are to be found at the extreme easterly edge of the plateau, and also on its more dissected parts (e.g., west of Darkes’ Forest, above Cataract Reservoir, and near Loddon Falls). Where the plateau abuts on the scarp, and on the gullies of these dissected regions, it exhibits bare rock at the edge, leading back to forest by a sequence of stages of vegetation, accompanied by an increase in soil depth. The plants nearest to the bare rock surface are most frequently xeric mosses, less frequently lichens, ferns (Polypodium Billardieri, Cyclophorus serpens) or orchids (Dendrobium lingui- forme, D. speciosum). Next in linear sequence comes a zone of herbs and straggling shrubs (e.g., Tillaea Sieberiana Schultes, Darwinia taxifolia), leading to a community of typical sandstone shrubs (notably Boronia pinnata, Actinotus Helianthi, and certain Epacridaceae), and so to Eucalyptus forest, the trees being frequently stunted in the zone of shallower soil.
The floristics and soil changes of this sere have been fully detailed by Pidgeon (1938, pp. 4-15), and will receive no further consideration here. The situations listed above, where the plateau gives place to the easterly scarp or to dissecting gullies, are characterized by a soil becoming more shallow as the sudden fall in surface is approached. It should be obvious that westerly migration of the scarp, or further
* Or uplift immediately preceding Pleistocene times.
BY CONSETT DAVIS. ial
dissection of the plateau by gullies (processes which are surely though gradually going on) can lead only to a decrease in size of the plateau, the communities of the plateau edge, which may be assumed to be more or less in equilibrium with the existing topography, being gradually forced backwards, whilst maintaining their present zonation. The immediate result of this process of erosion will be to denude of soil a greater percentage of rock than is exposed at present, although in some local instances conditions in newly-formed gullies will possibly be suitable for some of the postclimax communities dealt with in the preceding section.
Young trees of Hucalyptus gummifera have been noted on certain of the most easterly parts of the plateau, where shallow soil and bare rock form a mosaic of fairly level surface. Were it not for the westerly migration of the scarp, such a situation would almost certainly lead to the formation of the Hucalyptus Sieberiana Association. This development may be taking place in a few isolated cases, as the migration of the scarp is slow in terms of plant growth.
The rock exposures of the dissected areas (e.g., alternating ridges and gullies leading down to Cataract Reservoir) are more confused than those on the plateau edge, being usually represented by boulders projecting well above the soil surface. In such cases zonation is more abrupt and irregular than on the rock exposures of the more level areas of the plateau.
Zonation from rock to forest under wet, Swampy conditions is characteristic of many parts of the plateau. In some cases at least, as where the rock exposure is surrounded by soil, deepening to carry forest vegetation, it seems probable that autogenic succession in time is proceeding. The succession is marked by an increase in soil depth and, in the later stages, a lowering of the water-table. Soil properties, illustrating this, and the decreasing organic content, are listed in Table 3. It should be noted that, although the water-content of the soil is here shown as successively decreasing, this does not apply under all weather conditions; in dry weather, the water-content of the soil of the first stage falls below that of the swamp stage.
TABLE 3. Soil Properties for Moist Lithosere on Hawkesbury Sandstone.
Loss on Water — W.R.C. Ignition pH. Content (%
(%). (%). (2.7.38.) Wet Moss Stage : or sg aig AS 73 17-0 4-9 71-0 “*“Hemicryptophyte Stage ”’ at a 57 12-0 5-0 61-0 Local Swamp an fe ae a4 39 5:6 5-1 47-0 Local Swamp (with shrubs) Be ois 37 4-3 5:1 35-0 Eucalyptus micrantha Stage ae ahs 32 ae 5-4 14:0 Eucalyptus Sieberiana Association (climax) 25 205) 5-4 4-4
The earliest stage of this moist lithosere (Pl. i, G) consists of mosses (unidentified), which are followed by the ‘hemicryptophyte stage’ (Pidgeon, l.c.), the most prominent species of which is Lepyrodia scariosa; the herbs Drosera peltata, D. pygmaea, D. spathulata, Mitrasacme polymorpha and Utricularia lateriflora are also common. This stage leads, by deepening of the soil, to the swamp stage, of the following floristic composition:
N: A, Banksia latifolia, B. latifolia var. minor, Hakea pugioniformis, Epacris microphylla, Sprengelia incarnata; C, Symphyonema paludosum, Olax stricta, Viminaria denudata, Baeckea crenulata, B. linifolia, Leptospermum juniperinum Sm. ; O, Grevillea oleoides, Persoonia salicina, Aotus villosa, Dillwynia floribunda, Callistemon lanceolatus, Leptospermum lanigerum, Melaleuca squarrosa, Epacris obtusifolia, H. paludosa, Dampiera stricta; R, Banksia paludosa R.Br., Hakea dactyloides, Isopogon anemonifolius, Lambertia formosa, Stackhousia viminea;
12 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
VR, Persoonia lanceolata, Petrophila pulchella, Pultenaea elliptica, Pimelea linifolia, Melaleuca thymifolia, Trachymene linearis.
(Note: Some of the above shrubs, e.g., Grevillea, Isopogon, Lambertia, do not extend to the wettest parts of the swamps; most, however, are present under all conditions. The frequencies are for the average of a variety of local swamps.)
Ch: A, Bauera rubioides (incl. var. microphylla), Mitrasacme polymorpha; C, Drosera binata, D. spathulata, Euphrasia Brown, Utricularia lateriflora, Goodenia bellidi- folia; O, Drosera peltata, D. pygmaea, Boronia parviflora, Stylidium graminifolium Swartz; R, Hibbertia stricta; VR, Xanthorrhoea hastilis, Mitrasacme paludosa, Villarsia exaltata F.v.M., Utricularia dichotoma.
Islt A, Selaginella uliginosa, Gymnoschoenus sphaerocephalus, Hypolaena lateriflora Benth., Xanthorrhoea minor; C, Lindsaya linearis, Actinotus minor; O, Gahnia psittacorum, Tricostularia paludosa Benth., Xyris gracilis, Haemodorum plani- folium; VR, Caustis flexuosa, Juncus planifolius, Haemodorum teretifolium.
HH: A, Gleichenia dicarpa, Leptocarpus tenax, Lepyrodia scariosa, Restio complanatus, Chorizandra sphaerocephala, Lepidosperma laterale; LC, ‘Lycopodium laterale ; O, Blandfordia nobilis, Sowerbaea juncea; VR, Burchardia umbellata.
(Note: All apparently cryptophytie species are classed as helophytes.)
Th: O, Halorrhagis micrantha; R, Centrolepis strigosa.
E: R, Cassytha pubescens.
The Eucalyptus Sieberiana Association, which may be regarded as the climax under these conditions, is reached only where drainage factors allow the lowering of the average water-table. Hucalyptus micrantha Benth. usually forms a definite ecotone between the swamp and the climax (PI. i, H).
The parts of the swamp closer to the forest may be recognized as ‘shrub swamp’ (Pidgeon, l.c.); they are composed of the same species as are found in the swamp stage, with an increase in abundance of the shrubs found in the swamps, together with some shrubs less tolerant of a very high water-table. Even in the ‘shrub-swamp’, the shrub stratum is not nearly continuous; the ground stratum of both swamp and ‘shrub-swamp’ is continuous, the height of the vegetation being from 1—2 feet.
In one case, a young tree of Hucalyptus nicrantha was noted in the ‘shrub-swamp’ stage, well beyond the limits of the older trees, indicating successional relationship
in time.
(d). HEaxtensive Swamp or Moor Communities.
On the relatively flat parts of the plateau, usually on deep soils (presumably part of the late Tertiary peneplain), extensive swamp or moor communities develop, sometimes up to 2-3 miles in extent. These swamps are particularly well developed immediately to the north and west of Sublime Point. The inhibition of tree development is due primarily to the high water-table; wherever the average water-table falls below 3-4 feet, Hucalyptus Sieberiana, or more often H. micrantha Benth., develops. This relationship is shown in Figure I, a section west of the scarp about half a mile north of Sublime Point. The soil properties of this large swamp, which may be termed the Gymnoschoenus sphaerocephalus Community (Pl. ii, A), are shown in Table 4. The soil is characterized by a high organic content (some 60% of the loss-on-ignition figure
TABLE 4. Swamp Soils on Hawkesbury Sandstone.
= W.R.C. (%). Loss on Ignition (°%). pH.
Gymnoschoenus sphaerocephalus Community .. 81 21-0 4°8 91 23-0 4-7
120 25-0 4-8
Local Swamp 4 A a ake tt 58 16-0 5:0 Moor at Madden’s Plains =e hee a 33 3°5 seg) 39 4-2 4°8
40 BEvt 4°8
Shrub Swamps .. a 4 4 ae 45 4°6 4-8 46 6-1 5-0
37 4-3 oy
BY CONSETT DAVIS. 13
representing humus) and low pH. The plants of this community must tolerate a high water-table, with its resultant poor root aeration and high acidity. They are seldom subject to water shortage, although the surface soil to a depth of several inches occasionally becomes very dry in the higher parts of the community.
The floristics of this rather homogeneous community are set out below, the figures being those for eight quadrats each of one square metre. The numbers refer to each ascending shoot or cluster of vegetation; thus each ascending shoot of NSelaginella uliginosa was taken as one unit, and each tussock of Gymnoschoenus sphaerocephalus is made up of from six to ten units, representing separate clusters of vegetation. Life forms are given for the vascular species, the seedlings of shrubs being classed as nanophanerophytes. Because of the density of the vegetation (Pl. ii, C), it was necessary to remove each shoot or plant with shears as it was counted.
Species. Life-form. Shoots per sq. metre for eight quadrats Fossombronia sp. .. as ae is co —— iss + + Sphagnum sp. ae a on ae ve = sf a ar Dichaeta sp. ne me ae NE AiG —- + at ba Lycopodium laterale 3 x6 ae a HH. bys) | lb ae 3 1 29 57 Selaginella uliginosa He ee oN ate Tel. Wale RA aUAXGS SIZ 73 ‘1:29 98 167 Schizaea bifida .. oe oe af a HH. oh ee ae re Entolasia marginata Hughes .. as is H. ae 32 Ma 9 é ee ne ons Chorizandra sphaerocephala on a ef. HH. 12 7 12 11 9 15 5 2 Gymnoschoenus sphaerocephalus .. ae ps H. 18 12 12 46 46 21 17 Bul Hypolaena lateriflora Benth. .. oF oh 1els 49 28 47 69) (108) 5 alan 31 37 Lepidosperma Forsythii Hamilt. 5s a HH. 54 94 36 67 11 5 51 47 Lepidosperma laterale oA nts AG a HH. a} ate 2 Ee 4 fs 5 1 Leptocarpus tenax Pe is. BS sa AH. a 5 We 15 iat 29 3 15 Lepyrodia scariosa cee Se ae ie HH. a 5 30 1 27 5 13 Restio complanatus Bie ate Ae Ts HH. 10 4 2 19 21 5 11 Xyris gracilis x me A ot ye. H. ae 5 7 35 5 21 6 Xanthorrhoea minor os Ae Be an lal. 6 1 8 5 7 Banksia latifolia var. minor ae Phe Be N. Xs 27 ‘4: ate Sic At 1 Hakea pugioniformis a6 sis ee a N.- 1; isp isp 1t 1 Persoonia salicina ie we fis af N. a: pa 1 ae aS A As ae Drosera pygmaea .. oe a bes wh Ch. Je ae bus ie 3 i mF 2, Viola hederacea .. ie ae we ee Ch. bs ae is 3* Baeckea linifolia aN on ae ays N. a 1y eet Epacris obtusifolia ae hs ae Re N. ihe A47TT ws be QT 2 12; ye Mitrasacme polymorpha .. ae se oe Ch. as SG 19 10 20 iil a 15 Villarsia exaltata F.v.M. as a3 3 Ch. 37 QT 17 e ne 47 oe Utricularia lateriflora sg a ae Be Ch. Be cae ye 5 ae 3 oe 1 Goodenia bellidifolia Ss ae a = Ch. ae a 307 oy | 24 Dis; 57
* Weak plant. +Seedling. All apparently cryptophytic species are classed as helophytes.
From general inspection of other parts of this community, this table would appear to give a substantially correct picture of the floristics, except that Banksia latifolia (normal form) is as common as B. latifolia var. minor, and Lepidosperma Forsythii is generally less common than in the measured quadrats. In the lower parts of the swamp (Fig. 1), where the water-table is continuously at the surface, and where the water is usually moving in runnels or small creeks, Leptospermum juniperinum Sm. is developed in definite belts, sometimes with the addition of Gahnia psittacorum, rarely with a prominent belt of Lepidosperma Forsythit.
The community is exactly similar to the extensive ‘Button-grass Plains’ of Tasmania (especially important in western Tasmania and on the central plateau). The structure (tussocky vegetation 3-4 feet high, with smaller sedge-like vegetation and chamaephytic herbs at ground level, and occasional shrubs) is identical, and the most prominent species (Gymnoschoenus sphaerocephalus) is common to both. Many of the subsidiary species are common to both expressions of the community, though the Tasmanian development is, as would be expected, richer floristically, the present example being extra-limital.
14 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
Near the northern limit of the area studied, at Madden’s Plains, equally extensive swamp-like tracts occur for two to three miles west of the scarp. The soil is here shallower than in the swamps immediately north of Sublime Point, rock level often being reached at 18 inches, and the conditions are throughout drier. The vegetation, which may be conveniently termed a ‘moor’, has more of the appearance of the ‘shrub swamp’ stage noted above (under wet lithosere). Gymnoschoenus sphaerocephalus is less, Xanthorrhoea minor more prominent, than in the swamps near Sublime Point. Shrubs are generally more abundant, those present in the Sublime Point swamps being increased in frequency, and others (e.g., Melaleuca squarrosa) added. In one sector, the Madden’s Plains moor continues over a gentle rise to become continuous with the Sublime Point swamps immediately to the south.
The soils of the Madden’s Plains moors are less subject to high water-table, and have a correspondingly lower organic content, although the pH is as low as in the Sublime Point swamps (Table 4).
These swamp and moor communities, both in the Bulli district and in Tasmania, are, surprisingly, very liable to fires. This is most likely in dry seasons, but even in rather damp weather a fire will ‘run’ through the Gymnoschoenus sphaerocephalus Community, each tussock of the dominant having always a basal residue of dead, combustible leaves. In the spring of 1935, almost the entire area of the swamps near Sublime Point, and parts of Madden’s Plains, were swept by a fire which removed all the aerial parts of the vegetation. However, nearly all species of this community have hypogeal parts which, buried in wet soil, survived the fire. The sedge-like types possess submerged or half-submerged rhizomes, while some of the shrubs have subterranean root-stocks capable of regeneration. Within three weeks from the time of the fire, the rhizomes had begun to send up new shoots (Pl. ii, D); in one year the community had regained its normal appearance, both in height and structure, and floristically. The only noticeable change was the unexplained decrease in abundance of Lepidosperma Forsythii Hamilton.
The value of cryptophytic and hemicryptophytiec life-forms in swamp communities subject to fire is obvious; fire here replaces the unfavourable season, resistance to which formed the original criterion on which Raunkiaer based his life-form classification.
In the Bulli district, the high rainfall and relatively low saturation-deficit of the eastern parts of the plateau, where these swamp communities occur, probably assist in the retention of swamp conditions; other parts of the coastal range (e.g., the mountains behind Bateman’s Bay), where similar conditions of rain and mist prevail, possess similar extensive swamps. The regeneration of the swamp communities, after fire, to their former level, indicates that the reduction of saturation-deficit at the soil surface, due to the dense tangle of vegetation characteristic of these communities, is relatively unimportant in maintaining the communities in their present state. After fire, the vegetation being removed, there is no delay in evaporation due to vegetational cover; nevertheless, this temporary removal of the vegetation has no effect in raising the shrub element of the subsequent vegetation, or in altering the community in any way towards a drier state.
In Tasmania, the reasons for the high water-table conditioning this community are more dependent on climate (rainfall, saturation-deficit), and less on drainage- inhibiting topography, than in the present case. The Gymnoschoenus sphaerocephalus Community is so widespread in Tasmania as almost to justify its recognition as a climax formation (high moor), although the presence of neighbouring formations (sclerophyll forest, temperate rain-forest) where drainage is more efficient renders such a classification doubtful. The general preponderance of forest communities in the Bulli district, however, leaves no doubt that the Gymnoschoenus sphaerocephalus Community should there be regarded as a subclimax, widespread in extent, controlled topographically by poor drainage conditions. Causes of the high water-table, which in many cases is higher than the slope of the ground would otherwise allow, are the clay horizon at 4 feet depth (probably formed by the weathering of shale bands in the Hawkesbury Sandstone when these soils were originally formed, rather than by vertical
BY CONSETT DAVIS. 15
movement of the clay fraction), and the presence in many places of soil furrows at right angles to the slope (PI. ii, B), impeding water flow. These furrows alternate with parallel ridges carrying tussocky vegetation, distant from one to two yards, the variation in height between peak and trough of the soil surface being 4-12 inches. The furrows were particularly apparent in a visual survey of the area from the air. The troughs of these furrows have a relatively low percentage cover by vegetation. Their origin may possibly be sought in the burrowing activities of swamp crayfish,* which are very common in this area; the troughs of the furrows are characterized by the presence of holes, the retreats of the crayfish. Once started, the maintenance of this system of furrows is not difficult to explain, the crayfish remaining in the moister and more congenial trough regions, the vegetation favouring the better-drained and less disturbed ridges. The initiation of the furrow system, with its surprising regularity, is more difficult to explain. It has not been observed in this community in Tasmania, where, however, crayfish of the same general habits are equally common.
In the swamps noted under ‘wet lithoseres’, the high water-table is usually due to the contour of the underlying rock; this does not apply in the Sublime Point swamps, where the soil is very deep (Fig. 1), and even at Madden’s Plains, where the soil is shallower, the contour of the underlying rock is convex, and apparently would be ineffective in preventing lateral drainage.
Within the general area of the swamps, Hucalyptus micrantha Benth. develops wherever local conditions cause a lower water-table to occur (Pl. ii, E, F and G). These conditions are fulfilled in some cases by gentle hillocks or ridges, or above certain slight increases in the slope of the soil surface. Thus the Hucalyptus micrantha clump of Figure 1 (Pl. ii, F and G) is allowed by a relatively sudden, though still gentle, fall of the soil surface to the west of the clump (left in Figure 1) and to the north; the ground to the south of this clump carries the typical Gymnoschoenus sphaerocephalus Community, though it is on a slightly higher level than the clump. All such developments of Hucalyptus micrantha are bordered by a shrub zone (PI. ii, F and G).
In the cases of two such clumps, younger trees of H. micrantha extend beyond the general outline. This would indicate a local forward succession, possibly caused by a fall in water-table following erosion of the soil below the clump, with a consequent increase in slope.
Throughout the swamp and moor communities, species of ants (Myrmecia nigrocincta, and others) form nests by raising dead leaves and sand grains onto the tussocky vegetation. Calcination of such nests leaves a residue of over 50% by weight. In the forest communities, especially at..the ecotone of H. micrantha and swamp, these nests occur in considerable numbers, not raised, but on the surface of the drier soil. While this carriage of soil particles is discounted as a cause of local forward succession from swamp conditions, the effect of these ants in aerating the soil of swamp ecotone communities cannot be considered negligible.
On the rise between Madden’s Plains and the Sublime Point swamps, in a typical moor community, young trees of Hucalyptus gummifera have developed during the last eight years (Pl. ii, H). The reason for this is unknown. It is very surprising to find this species apparently initiating a local succession to forest vegetation, instead of EH. Sieberiana or E. micrantha, which are more tolerant of swamp conditions.
In conclusion, it may be stated that a general succession from these swamps and moors to forest can occur only when the drainage conditions are improved by a change in topography, by artificial drainage channels or by the gradual erosion of the plateau surface, e.g., further extension of the Loddon Falls gorge.
(e). Vegetation of the Scarp.
The vegetation of the scarp is efficiently sheltered from westerly winds, and from the sun after noon. Variations in the water-supply, from situations where the soil is continuously damp to those where it is usually very dry, account for the diversity of
* Huastacus hirsutws (McCulloch).
16 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
species encountered. As a whole, the vegetation may be regarded as a retrograde lithosere, growing in unstable circumstances. In general, dynamic equilibrium obtains between the normal processes of autogenic succession and the retrograde influences of soil denudation and falling rock.
Drier areas consist of bare rock, partly covered by mats of Cyclophorus serpens, Polypodium Billardieri and Dendrobium linguiforme, with the nanophanerophytes, Xanthorrhoea arborea R.Br. and Actinotus Helianthi, developing where sufficient soil is formed. Moister areas consist of a mosaic of bare rock, liverworts and mosses, and, where sufficient soil is formed, the following species:
N: (Shrubs, or trees less than six feet in height.) Banksia ericifolia, Doryphora Sassafras, Callicoma serratifolia, Ceratopetalum apetalum, Pultenaea daphnoides, Cryptandra ericifolia, Pomaderris phillyroides, Backhousia myrtifolia, Leptosper- mum stellatum, Melaleuca hypericifolia, Tristania laurina, Dracophyllum secundum, Epacris coriacea, E. longiflora and Leucopogon lanceolatus.
Ch: Todea barbara, Billardiera scandens, Viola hederacea, Halorrhagis teucrioides, Xanthosia pilosa, X. tridentata. EG: Blechnum capense, B. Patersoni, Gleichenia dicarpa, Gahnia psittacorum, Hypolaena
lateriflora Benth. (N.B. Hemicryptophytic under these conditions; some of the species are cryptophytic in deeper soils.) B: Cassytha paniculata. The above species include some of the more mesophytic species of the Hucalyptus Sieberiana Association, some brush species, and a few swamp types restricted to seepage areas on the scarp.
(2). Wianamatta Shale.
Vegetation at Darkes’ Forest may be classed as the Angophora lanceolata facies of the Hucalyptus piperita Association (Pl. i, F). Structurally, it represents high forest (80-100 ft.), canopy subdiscontinuous, with a prominent low-tree stratum, an almost continuous shrub stratum, and a ground stratum, continuous only where the shrubs are least dense. Floristically, its composition is as follows:
MM: A, Angophora lanceolata, Eucalyptus piperita; O, Hucalyptus eugenioides, FE. gummifera; R, Hucalyptus micrantha Benth., H. Sieberiana.
M: C, Acacia binervata, A. longifolia; O, Hakea saligna, EHxocarpus cupressiformis, Rapanea variabilis Mey.; R, Acacia decurrens var., A. rubida, Leptospermum stellatum.
N: A, Banksia ericifolia, B. spinulosa, Persoonia salicina, Acacia myrtifolia; C, Hakea
pugioniformis, Lambertia formosa, Acacia discolor, Pultenaea daphnoides, Dampiera Brownii; O, Hakea dactyloides, Lomatia silaifolia, Persoonia ferruginea, P. lanceo- lata, Leptomeria acida, Pimelea linifolia, Hpacris pulchella, Olearia ramulosa Benth. ; R, Banksia paludosa R.Br., Lomatia ilicifolia, Leucopogon esquamatus, L. lanceo- latus, Cassinia aurea, Olearia viscidula Benth.
N (climber): C, Smilax glycyphylla, Kennedya rubicunda.
Ch: C, Doryanthes excelsa, Hibbertia Billardieri, Halorrhagis teucrioides; O, Schoenus imberbis, Glycine clandestina, Viola hederacea; R, Patersonia glauca.
Isle A, Paspalum dilatatum Poir. (introd.); C, Culcita dubia, Blechnum cartilagineum, Lindsaya microphylla, Lomandra longifolia, Rubus fruticosus (introd.). :
G: C, Pteridium aquilinum; R, Pterostylis nutans.
Th: C, Hypochaeris glabra (introd.); O, Poa annua (introd.), Gnaphalium purpureum.
B: C, Loranthus celastroides.
Soil properties for this community are given in Table 5. They give no indication why the community should appear to be a.sandstone one, enriched by a few more mesophytie species, rather than a true shale community. The absence of such trees as Bucalyptus pilularis and Syncarpia laurifolia Ten., characteristic of the Wianamatta Shale in other districts, is inexplicable. Trees of Eucalyptus globulus, introduced in this area, flourish at Darkes’ Forest.
(3). Narrabeen Series.
In some areas between Bulli Lookout and Broker’s Nose, the Hawkesbury Sandstone beds have been removed by erosion to expose the Narrabeen beds (ezine al, deal, Say). These latter consist of an upper layer of Chocolate Shale some 50 feet in depth, below which is a considerable thickness of rather fine-grained Narrabeen Sandstone. Erosion
BY CONSETT DAVIS. ily?
TABLE 5. Properties of Soils of Wianamatia and Narrabeen Series.
— W.R.C: (%). Loss on Ignition (%).* pH. Wianamatta Shale. Eucalyptus piperita Association (Angophora 91 28 5:0 lanceolata facies) .. V6 ae Ses 91 25 5-1 97 24 5-5 Narrabeen Sandstone. Eucalyptus piperita Association, no physio- graphic shelter .. as he ay 50 18 5:6 Eucalyptus saligna Association, partial physiographic shelter Se ae Me 58 31 5-6 Chocolate Shale. Eucalyptus saligna Association, no physio- 53 16 5-6 graphic shelter .. Ko o8 bet 60 14 6:3 62 16 5-2, 71 16 522, 76 23 5-9 Brush, partial physiographic shelter ee 100 39 5-5 130 36 HOB}
* Only a small fraction of this figure represents humus.
A, Horizon. Water Held at Sand Fraction Index of Derivation of Soil. Sticky-Point (%). (%). Texture. Wianamatta Shale aye ae XG be 49-0 82 33 50-1 83 33 53-0 72 39 55:0 70 41 Chocolate Shale .. Abe Pi ns ie ~ 46-4 94 28 49-0 92 31 50-7 89 33 Narrabeen Sandstone, relatively pure. . aes 30-0 93 11 Narrabeen Sandstone, contaminated with 45-0 95 26 _ Chocolate Shale =e Ae ue Le 46-7 95 28
of these beds is only incipient, and the Chocolate Shale weathers more rapidly than the underlying sandstone; under these circumstances, it is impossible to find a Narrabeen Sandstone soil uncontaminated with at least a small fraction of the shale soil. This, and the variation in slope and shelter, lead to some confusion in the arrangement of communities. It appears that on the least contaminated of the Narrabeen Sandstone soils, Hucalyptus piperita is dominant in unsheltered situations, with E. eugenioides, H. gummifera, EH. pilularis and EH. saligna of occasional occurrence, E. paniculata and #. Sieberiana rare. On the soils of the Chocolate Shale (except where physiographic shelter leads to the development of brush), and in moderately sheltered positions on the Narrabeen Sandstone, Hucalyptus saligna is dominant, with #. pilularis and Syncarpia laurifolia Ten. common, and H. eugenioides, H. paniculata and EL. piperita rare. Introduced pine-trees (Pinus radiata) also occur in these communities.
The structure of these communities, which may be termed the Hucalyptus piperita and H. saligna associations respectively, is similar to the Darkes’ Forest (Wianamatta Shale) community. Soil properties are shown in Table 5. The following represents a reasonably complete estimate of the floristics, most species being common to both associations:
MM: See above. M: C, Hxocarpus cupressiformis, Acacia longifolia, A. mollissima; R, Hakea sailigna.
18 PLANT ECOLOGY OF THE BULLI DISTRICT. II,
N: A, Persoonia salicina, Idigofera australis, Pomaderris elliptica, Pimelea ligustrina, Prostanthera Sieberi Benth.; C, Banksia spinulosa, Persoonia ferruginea, P. lanceo- lata, Acacia discolor, A. suaveolens; O, Persoonia revoluta, Acacia myrtifolia, Zieria Smithii, Astrotricha floccosa, Cassinia longifolia; R, Persoonia linearis, Pultenaea daphnoides, Dodonaea triquetra, Lasiopetalum ferrugineum, Helichrysum diosmi- folium, H. elatum; VR, Xylomelum pyriforme, Citriobatus multiflorus, Pultenaea
flexilis.
Ch: C, Hibbertia Billardieri, Halorrhagis teucrioides; O, Kennedya rubicunda, Viola hederacea; R, Billardiera scandens, Geranium pilosum.
IShE LC, Blechnum cartilagineum, Imperata cylindrica var. Koenigii, Paspalum dilatatum
Poir. (introd.), Rubus fruticosus (introd.) ; O, Cynodon dactylon; R, Culcita dubia, Bragrostis Brownii, Stipa pubescens.
G: A, Pteridiuwm aquilinum.
Th: O, Poa annua (introd.), Hypochoeris glabra (introd.); R, Gnaphalium luteo- album, G. purpureum. ;
E: O, Loranthus celastroides, Cassytha paniculata; VR, Cymbidium suave.
In conditions of partial shelter from the west, brush develops on the Chocolate Shale; this formation occurs in efficient shelter on the Narrabeen Sandstone. It is structurally similar to the coastal brush to be described in the next part of this series. The only species present in the brush of the Narrabeen beds on the plateau area yet absent from the brush of the coastal slopes is the tree-fern, Dicksonia antarctica.
In parts of the Hucalyptus saligna Association (supra), where shelter is slightly too inefficient for true brush to develop, some species (e.g., Livistona australis, Alsophila australis) are added, giving the vegetation the nature of an ecotone community.
Around the borders of Cataract Reservoir (Pl. i, 1), the vegetation shows a regular zonation conditioned by artificial raising of the water-table. Myriophyllum propinquum A. Cunn. is the chief representative of the floating stage; occasionally, fall in water level in the reservoir leaves this species on the drying mud surface, where it persists for a time as a land plant, usually forming red pigment. Near the upper limit of the water a hemicryptophytic zone occurs, with Juncus pallidus, J. bufonius, Poa annua (introd.), Gratiola Peruviana and, further back, Imperata cylindrica var. Koenigii. When expanses of mud are exposed below this zone by a fall in water level of long duration, therophytes temporarily colonize it (e.g., Centipeda minima A.Br. et Aschers, Hrigeron crispus Pourret (introd.)). Behind the hemicryptophytic zone, the Hucalyptus saligna Association is present, shrubs of Melaleuca squamea and Leptospermum flavescens occupying an intermediate position where the high water-table inhibits tree development.
Acknowledgements.
My thanks are due to Mr. O. D. Evans of the Botany Department, Sydney University, and to Dr. F. Rodway of Nowra, for determining many of the species cited. Thanks are also due to Mr. D. Rochford of the Zoology Department, Sydney University, for the estimation of chloride in soil filtrates.
List of References.
Buack, J. M., 1929.—Flora of South Australia, i-iv. S. Aust. Govt. Printer. Davis, C., 1936.—Plant Ecology of the Bulli District, Part i. Proc. Linn.’Soc. N.S.W., 1xi, 285-297. FRASER, LILIAN, and VickERY, Joyce, W., 1937.—The Ecology of the Upper Williams River and Barrington Tops Districts. i. Introduction. Proc. Linn. Soc. N.S.W., lxii, 269-283. , 1958.—The Ecology of the Upper Williams River and Barrington Tops Districts. ii. The Rain-forest Formations. Ibid., lxiii, 139-184. , 1939.—The Ecology of the Upper Williams River and Barrington Tops Districts. ili. The Eucalypt Forests and General Discussion. Movil, Ibahie Iles} Harpy, F., 1928.—An Index of Soil Texture. J. Agric. Scet., xviii. Lacatu, H., and Sicarp, L., 1911.—Contribution a l’étude des terres salées du littoral méditer- ranéen. Ann. Ministére d’Agric., 40. Maipen, J. H., and Bercuer, E., 1916.—A Census of New South Wales Plants. N.S.W. Govt. Printer. MELVAINE, ALMA T., 1936.—A Check-list of the New South Wales Pteridophytes. Proc. LINN. Soc. N.S.W., Ixi, 111-121. rigs et and Brercue, B., 1893.—Handbook of the Flora of New South Wales. N.S.W. Govt. *rinter.
OsgBorN, T. G. B., and Ropertson, R. N., 1939.—A Reconnaissance Survey of the Vegetation of the Myall Lakes. Proc. Linn. Soc. N.S.W., Ixiv, 279-296.
BY CONSETT DAVIS. 19
PIDGEON, ILMA M., 1937.—The Ecology of the Central Coastal Area of New South Wales. i. The Environment and General Features of the Vegetation. Proc. LINN. Soc. N.S.W., Ixii, 315-340.
, 1938.—The Ecology of the Central Coastal Area of New South Wales. ii. Plant Succession on the Hawkesbury Sandstone. Ibid., Ixiii, 1-26.
Woop, J. G., 1937.—The Vegetation of South Australia. S. Aust. Govt. Printer.
EXPLANATION OF PLATES I-II. Plate i.
A.—EHucalyptus Sieberiana Association on Hawkesbury Sandstone, south of Cataract Reservoir.
B.—Eucalyptus Sieberiana Association on Hawkesbury Sandstone, south of Sublime Point. The soil is rather shallow, and rock outcrops occur.
C.—Eucalyptus piperita Association on Hawkesbury Sandstone, upper slopes of gully south of Cataract Reservoir.
D.—Eucalyptus pilularis Association on Hawkesbury Sandstone, lower slopes of gully south of Cataract Reservoir.
H.—Depauperate brush (subtropical rain-forest formation) on Hawkesbury Sandstone, bottom of Loddon Falls Gorge.
F.—Eucalyptus piperita Association (Angophora lanceolata facies) on Wianamatta Shale soil, Darkes’ Forest.
G.—First stages of zonation from exposed Hawkesbury Sandstone rock under moist soil conditions (moist lithosere) ; mosses, and Lepyrodia scariosa. Near Loddon Falls.
H.—Moist lithosere near Loddon Falls. Hawkesbury Sandstone outcrop in foreground, leading by moss and ‘hemicryptophyte’ stages to swamp and forest. Trees with pale trunks in middle distance are Hucalyptus micrantha Benth., passing to Hucalyptus Sieberiana Associa- tion in background.
I.—Zonation beside Cataract Reservoir, Narrabeen Series.
Plate ii.
A.—Gymnoschoenus sphaerocephalus Community north of Sublime Point.
B.—Natural contour furrows in Gymnoschoenus sphaerocephalus Community north of Sublime Point. The position of the furrows is indicated by oblique lines of darker vegetation, corresponding to the wetter nature of the soil.
C.—Metre quadrat in Gymnoschoenus sphaerocephalus Community, north of Sublime Point.
D.—Gymnoschoenus sphaerocephalus Community north of Sublime Point, regenerating after a fire which had removed all aerial parts one month previously. Gymnoschoenus sphaerocephalus and Xanthorrhoea minor shooting from hypogeal remains.
H.—Clump of trees of Hucalyptus micrantha Benth. surrounded by Gymnoschoenus sphaero- cephalus Community, south of Cataract Reservoir. Note young tree on left of clump.
F, G.—Clump of young trees of Hucalyptus micrantha Benth. in Gymnoschoenus sphaero- cephalus Community north of Sublime Point. The zone of shrubs outlying the trees corres- ponds to intermediate conditions of water-table (cf. Fig. 1).
H.—Gymnoschoenus sphaerocephalus Community at Madden’s Plains, with bushes and young trees of Hucalyptus gummifera developing.
APPENDIX. Life-Form Spectra for Communities of Plateau.
No. of MM. M. N. Ch. H. (Gi IeUEI, Nn, S. E. Species.
Eucalyptus Sieberiana Association .. 4 5 54 19 11 5 ae Ade @ 130 Swamp and Shrub Swamp (moist
lithosere) .. bos a a aS at 43 22 18 = 13 3 a 1 74 Gymnoschoenus sphaerocephalus Com-
munity Ave os Ns ae ae a 20 24 24 at 32 os a a 25 Eucalyptus piperita Association (Ango-
phora lanceolata facies) , 12 14 42 12 10 3 5) 2 59
Eucalyptus saligna and EH. piperita Associations (Narrabeen Series) 15 7 41 10 13 2 ae 7 tne 5 59
PLANT ECOLOGY OF THE BULLI DISTRICT. PART II: PLANT COMMUNITIES OF THE COASTAL SLOPES AND PLAIN. By Consett Davis, M.Se., Lecturer in Biology, New England University College. (Plates iii—iv.)
[MS. received 9th February, 1940. Read 26th March, 1941.]
(1). Eucalyptus pilularis Association.
This community occupies soils of the Narrabeen Sandstone and Upper Coal Measures on the coastal slopes and plain where conditions are not favourable for the development of brush (subtropical rain-forest) or brush ecotone communities. One exception is the community occurring on soils derived from tuffaceous mudstone (Upper Coal Measures) at Towrodgie (infra). Settlement has caused destruction or alteration of large areas of the Hucalyptus pilularis Association, much of the community as it exists at present representing second-growth timber of the dominant. Even where the high trees are untouched, the lower strata are often much altered by clearing and grazing, fire, and introduced plants. Areas from which the dominant has been entirely cleared have been omitted from the present study. j
Structurally, the community (Pl. iv, A) comprises a high tree stratum of the dominant, together with Hucalyptus paniculata and Syncarpia laurifolia Ten., reaching over 150 feet in height in some cases; the canopy is never continuous. Mesophanerophytes (Casuarina torulosa, Acacia binervata) are moderately frequent on the slopes; micro- phanerophytes are seldom prominent. The shrub layer is rather sparse; the ground layer, chiefly hemicryptophytic, is almost continuous except on the driest ridges.
Soil properties (Table 1; for methods, see Part ii of this series) exhibit a wide range. The lowest figures for water-retaining capacity (30-36%) show no improve- ment over the Hawkesbury Sandstone soils of the plateau (cf. Hucalyptus Sieberiana Association, Part ii of this series), but the lower (e.g., B) horizons of the Upper Coal Measures soils show a marked increase in water-retaining capacity over the surface soils to which Table 1 applies.
TABLE 1. Soil Properties for Eucalyptus Associations of Coastal Slopes and Plain.
Loss on Ignition
a W.R.C. (%). (%). pH. Eucalyptus pilularis on soils of Upper Coal 30 2°38 6-2 Measures (Shales and Sandstones) a 34 (2% 5:8
36 10-0 : 5:5
49 5e3 57
49 9-2 5-5
69 4-8 6-2
69 11-0 5-8
Mixed Eucalyptus Forest on tuffaceous mudstone 53 14:0 5°5 soil, Upper Coal Measures a wa 88 18-0 5-2
97 19-0 5-2
Mixed Lucalyptus Forest on recent alluvial soil 63 13:0 6-3 (climax to subsaline lagoon succession) .. 71 14:0 6°3
83 18:0 6-1
91 20-0 6-0
The following is a floristic estimate of the less disturbed parts of this association:
MM: A* (dominant), Hucalyptus pilularis; C, Casuarina torulosa (slopes only), Hucalyptus paniculata, Synecarpia laurifolia Ten.; O (LC), Acacia binervata,
* Abbreviations for life-form, frequency, and localization, as in Part ii of this series.
BY CONSETT DAVIS. 21
Eucalyptus eugenioides (plain only), E. saligna (brush ecotone dominant); VR, Hucalyptus botryoides.
O, Persoonia linearis, Leucopogon lanceolatus, Rapanea variabilis Mey., Notelaea longifolia; R, Hlaeocarpus reticulatus; VR, Acacia mollissima.
N: A, Acacia myrtifolia, A. suaveolens; C, Persoonia salicina, Indigofera australis, Oxzylobium trilobatum, Pimelea ligustrina, Goodenia ovata, Helichrysum diosmi- folium, Senecio dryadeus Sieb.; O, Zieria Smithii, Sida rhombifolia, Prostanthera Sieberi Benth., Helichrysum bracteatum Willd., H. elatum, Olearia ramulosa Benth. ; O (LL), Hakea pugioniformis, Citriobatus multiflorus, eptospermum flavescens, Lantana camara (introd); R, Pimelea linifolia, Cassinia denticulata, Olearia argophylla F.v.M.; VR, Phyllota phylicoides, Pultenaea flevilis.
N (climbers): C, Smilax glycyphylla, Clematis aristata, Billardiera scandens; O, Geitono- plesium cymosum.
Ch: <A, Hardenbergia monophylla, Hibbertia dentata; C, Viola hederacea, Plantago lanceolata (introd.); O, Dianella longifolia, D. revoluta, Glycine clandestina, Geranium pilosum, Hibbertia Billardieri, Halorrhagis teucrioides, Astroloma humi- fusum; R, Dianella coerulea, Hypoxis hygrometrica, Tillaea Sieberiana Schultes, Bossiaea prostrata; VR, Desmodium varians, Plantago varia.
1Bf2 A, Paspalum dilatatum Poir. (introd.), Rwbus fruticosus (introd.); C, Doodia aspera, Cynodon dactylon, Eragrostis Brownii (including var. patens), Imperata cylindrica var. Koenigii, Carex paniculata, Lomandra longifolia Labill.; LC, Selaginella uliginosa; O, Themeda australis Stapf., Lomandra multiflora Britt., Oxwalis corniculata; O (lL), Adiantum aethiopicum, Asplenium flabellifolium; R, Blechnum cartilagineum, Calamagrostis quadriseta Spreng., Oplismenus compositus, Poa caespitosa; VR, Stipa pubescens, Luzula campestris, Lomandra filiformis J. Britten.
G: A, Pteridium aquilinum; O, Schelhammera undulata, Caladenia carnea, Dipodiuwm punctatum, Pterostylis nutans; O (LL), Burchardia umbellata, Microtis porrifolia; R, Tricoryne simplex, Caladenia alba; VR, Schizaea dichotoma, Calochilus campestris, Pterostylis ophioglossa.
E: C, Loranthus celastroides; O, Cassytha paniculata; VR, Cassytha glabelia.
Th: A, Hypochoeris glabra (introd.); C, Wahlenbergia gracilis, Gnaphalium japonicum, Sonchus oleraceus (introd.) ; O, Poa annua (introd.), Phytolacca octandra (introd.), Anagallis arvensis (introd.), Hrythraea australis, Solanum nigrum, Gnaphalium luteo-album, G. purpureum, Taraxacum officinale Weber (introd.); R, Stellaria flaccida, Erechthites arguta DC. ;
On the wider parts of the coastal -plain (e.g., near Corrimal) both Syncarpia laurifolia Ten. and Hucalyptus eugenioides assume a position of local dominance in a few cases. Casuarina torulosa is absent from these areas, being characteristic of the slopes. Hucalyptus saligna is not a typical member of this association, being rather the dominant of the brush ecotone community, which might almost be considered as part of the Hucalyptus saligna Association noted in Part ii of this series.
The absence of such trees as Hucalyptus gummifera and H. Sieberiana from the sclerophyll forests of the slopes and plain is somewhat surprising; it may be due to the higher pH of these areas (5:5-6:2, as opposed to 4:9-5-4 for soils carrying these species on the plateau), or to competition.
Mixed Eucalyptus Forest.
On the north side of Towrodgie Creek a Mixed Hucalyptus Forest occurs on soils derived from a tuffaceous mudstone, a local representative of the Upper Coal Measures. Soils from this situation are finer in texture* than is normal for the Upper Coal
* Samples from the A, horizon of the mudstone soil and of other Upper Coal Measures soils have the following properties:
Water Held at Sand Fraction Index of —_— Sticky-Point (%). (S))- Texture. Mudstone ts ape sls a3 ba By/ 015) 85 20 38-0 84 21 Other Upper Coal Measures soils se ae 19-0 88 2 19:5 87 3 25-9 95 a 44-6 71 31 45-0 70 31
bo bo
PLANT ECOLOGY OF THE BULLI DISTRICT. III,
Measures, but this does not adequately explain the difference between the vegetation and the normal HLucalyptus pilularis Association. The area is close to the sea, and only a slight distance above the level of a subsaline lagoon; however, on the south side of Towrodgie Creek a pure stand of Hucalyptus pilularis is developed on soil derived from Upper Coal Measures shale, in an otherwise exactly comparable situation.
The trees of this mixed forest are lower than those of the Hucalyptus pilularis Association, and somewhat gnarled (Pl. iv, B), possibly as a result of sea-winds. Co-dominants are Hucalyptus eugenioides, HE. longifolia, E. paniculata and E. punctata, with #. botryoides occurring occasionally. The lower strata, when undisturbed, resemble those of the Hucalyptus pilularis Association, including low trees of Notelaea longifolia, shrubs of Acacia myrtifolia, Oxylobium trilobatum and Pimelea linifolia, and a ground layer of Pteridium aquilinum, Cynodon dactylon, Burchardia umbellata and annuals such as Hypochoeris glabra, as its most important members. To these are added elements of the seres discussed below (e.g., Leucopogon Richei and Hibbertia volubilis from the psammosere, and Gahnia psittacorum from the subsaline hydrosere), and a few brush species (e.g., Clerodendron tomentosum).
The whole community agrees closely with the neighbouring Mixed Hucalyptus Forest occurring on recent alluvial soils, and interpreted as climax of the lagoon sere. This resemblance may possibly be explained by the assumption that the soil in the present case, though derived from the underlying rock, has in the recent past been partly flooded by lagoon waters, which have since been lowered by allogenic causes.
(2). Brush (Subtropical Rain Forest).
Brush is developed on soils derived from the Narrabeen Sandstone and Upper Coal Measures wherever sufficient shelter occurs, usually in situations with a copious supply of soil water. The formation occurs on the Chocolate Shale on the dissected parts of the plateau, tolerating on soils of this rock type either situations of efficient shelter, but low average soil moisture (e.g., immediately below the top of Bulli Pass), or situations with slight shelter from the west, but with a better supply of soil moisture (e.g., immediately west of the top of Bulli Pass; Davis, 1936, Pl. xv, J). Development of brush on Hawkesbury Sandstone soils is limited to areas of extreme shelter (cf. Part ii of this series).
Three main factors, then, enter into the conditioning of brush development. (1) Physiographic shelter from dry (westerly) winds and, to a less extent, from insolation; (2) supply of soil moisture, dependent on drainage and evaporation; and (3) soil type as conditioned by parent rock. Factors (2) and (3) react together to some extent to govern the ultimate soil type, moisture supply governing humus formation, which, with the texture of the soil as formed from rock decomposition, determines the water-retaining capacity.
Considering these three variables, two facts seem clear: (i) Brush is able to develop in situations of decreasing shelter on soils of increasing fineness of texture; the series Hawkesbury Sandstone-Narrabeen Sandstone-Upper Coal Measures-Chocolate Shale seems to apply. The last-named soils have, it is true, a coarser texture than some of those of the Upper Coal Measures, yet there seems no doubt that they are the best soils of this district. Chemical as well as physical properties of the soils may explain this fact. (ii) Shelter from wind and sun seems more important than soil conditions in brush development. Thus, for the soils listed in Table 2, only low-grade brush (practically equivalent to the Eucalyptus saligna ecotone Community) develops on the last soil listed, which, with partial physiographic shelter, has better properties than the seventh soil listed, a dry, well-drained soil carrying highly-integrated brush in a position of extreme shelter. However, the fifth and sixth soil-samples listed, with excellent properties, carry highly-integrated brush with very slight shelter from the west.
Brush develops on the upper coastal slopes, immediately below the scarp, except on several prominent ridges, where the Hucalyptus pilularis Association or EH. saligna ecotone Community reaches the scarp. These upper slopes correspond to Narrabeen
BY CONSETT DAVIS. 23
Sandstone; Chocolate Shale exposures are very limited in extent on the slopes, except where the protecting Hawkesbury Sandstone cover has been entirely removed, as at the top of Bulli Pass. Soils of the upper slopes, at the level of the Narrabeen Sandstone, are contaminated with soil derived from overlying series, most markedly where erosion of the soft Chocolate Shale has been permitted by removal of the Hawkesbury Sandstone.
TABLE 2. Properties of Soils carrying Brush (or Subtropical Rain Forest).
Loss on Ignition
eee W.R.C. (%). (%).* pH. Hawkesbury Sandstone, extreme shelter Aa 90 30-0 5-2 120 35:0 5-2 120 49-0 53GB: 130 48-0 5-0 Chocolate Shale, partial shelter on plateau .. 100 39-0 5-5 130 36-0 5°3 Easterly Slopes: soil derived chiefly from 60 21-0 5-8 Chocolate Shale, very efficiently drained ; 66 13-0 5°8 extreme shelter. Easterly Slopes: soil derived from Narrabeen 200 38-0 6-9 Sandstone mixed with talus from formations above ; soil moisture high ; shelter extreme to moderate. Partial shelter; soil as above: Low-grade 61 9-4 5-9
Brush.
* Irom 20% to 60% of this figure represents humus.
On the lower slopes, brush is restricted to gullies and to the inner (western) side of the larger terraces. Depauperate brutish occurs beyond these limits, and probably many parts of the coastal plain once carried a brush element, prior to disturbance following settlement. The alternation of brush, sclerophyll and ecotone communities has been studied in a belt-transect between the 200-ft. contour and the scarp at Coledale; true brush extended down to the inner side of a terrace a little above the 400-ft. contour; below this, ecotone communities wert present on terraces, but sclerophyll forest characterized other parts of the ridge followed. In a transect at right angles to the above, between two ridges running down from the upper slopes to the sea, brush was developed only at the lowest point, ecotone vegetation on the ridge facing south (except at its summit), sclerophyll forest on the summits of both ridges and on all except the lowest part of the north-facing ridge. ,
The brush studied has the characteristic facies of this formation as found in other parts of the State, namely a variety of trees of medium height, mostly laurel-leaved, with continuous canopy; paucity of small trees in most cases, except the tree-fern Alsophila australis; almost complete absence of shrubs, and presence of a discontinuous ground layer composed chiefly of ferns. In addition, epiphytes and climbers are common.
Omitting high sclerophyllous trees which occasionally grow in the brush, penetrating the canopy (ELucalyptus pilularis, BE. saligna, and more rarely Syncarpia laurifolia Ten., Eucalyptus paniculata and H. quadrangulata Deane and Maiden), and the elements characteristic of the brush-sclerophyll forest ecotone, but absent from the true brush, the floristics may be set out as follows:
MM: A, Livistona australis, Ficus stephanocarpa Warb., Doryphora Sassafras; C, Ficus rubiginosa, Laportea gigas, Pennantia Cunninghamii, Cryptocarya glaucescens, Endiandra Sieberi, Callicoma serratifolia, Pittosporum wundulatum, Ceratopetalum apetalum, Omalanthus populifolius, Sloanea australis, Hugenia Smithii, Trochocarpa laurina, Sideroxylon australe, Cargillia australis R.Br.; O, Archontophoenix Cunninghamiana Wendl. et Drude, Polyosma Cunninghamiti, Schizomeria ovata,
24 PLANT ECOLOGY OF THE BULLI DISTRICT. MII,
Pittosporum revolutum, Claoxylon australe, Diploglottis Cunninghamii, Brachychiton acerifolius F.v.M., Eugenia myrtifolia, Panax Murrayi, Clerodendron tomentosum ; R, Mollinedia macrophylla, Cryptocarya microneura, Tristania laurina; VR, Podocarpus elata, Pisonia Brunoniana, Quintinia Sieberi, Melia Azedarach.
MM (climbers): C, Smilax australis, Clematis glycinoides, Sarcopetalum Harveyanum, Stephania hernandifolia, Palmeria scandens, Lyonsia straminea, Tecoma pandorana Skeels, Senecio mikanioides Otto (introd.) ; O, Piper hederaceum, Vitis hypoglauca, Lyonsia reticulata; R, Tylophora barbata.
M: A, Alsophila australis; C, Panax sambucifolius, Psychotria loniceriodes; O, Drimys insipida Druce, Sambucus sxanthocarpa; R, Croton Verreauxii, Phyllanthus Gastroemi, Backhousia myrtifolia.
M (climbers): C, Hustrephus latifolius R.Br., Rubus parvifolius; O, Rubus Moluccanus, R. Moorei; R, Rubus rosifolius, Passiflora Herbertiana, Panax cephalobotrys.
N: A, Lantana camara (introd.) (chiefly in disturbed areas); O, Citriobatus multi- florus; R, Abrophyllum ornans. ED: A, Adiantum aethiopicum, A. formosum, Asplenium flabellifolium, Polystichum
aculeatum; C, Blechnum capense, B. Patersoni, Pellaea falcata; O, Adiantum diaphanum, Dryopteris decomposita, Hypolepis tenuifolium, Sisyrinchium panicu- latum; R, Adiantum hispidulum.
A, Gymnostachys anceps; C, Histiopteris incisa, Pteris uwmbrosa.
A, Cyclophorus serpens, Pleopeltis diversifolia, Peperomia reflexa, Arthropteris tenella, Hymenophyllum tunbridgense; C, Polypodium Billardieri; O, Davallia pyxidata, Cymbidium suave, Sarcochilus falcatus; R, Asplenium nidus, Platycerium bifurcatum; VR, Tmesipteris tannensis.
The ecotone between the brush and the EHucalyptus pilularis Association is dominated by Hucalyptus saligna, and contains the more tolerant of the species of the true brush (e.g., Livistona australis, Omalanthus populifolius, Alsophila australis, Lantana camara, Rubus parvifolius), together with certain species confined to the ecotone, and not extending into the true brush except in cleared spaces. The low trees, Breynia oblongifolia, Hupomatia laurina, Synoum glandulosum and Rhodamnia trinervia, fall in this category, and the higher Acacia binervata, which can stand drier conditions, is frequently prominent. The climbers, Smilax glycyphylla and Hustrephus latifolius R.Br., occur in this ecotone community, together with a ground layer including Adiantum aethiopicum, Oplismenus compositus, Pollia cyanococca, Urtica incisa, Rubus fruticosus (introd.), Stellaria flaccida, Plectranthus parviflorus and Brunella vulgaris L.
The present record of a sample of the Illawarra brush indicates that it is poorer floristically than the brush forests of northern New South Wales (cf. Fraser and Vickery, 1938). The list given is probably not complete, even for the area studied, but there can be no doubt that a number of species of this northern formation fail to reach as far south as the Bulli district. Some species (e.g., Cedrela australis) known to have occurred in the district in the past have not been met with; Cedrela may be extinct in the district (by reason of the demand for its timber), though specimens occur in the Gerringong area, a little to the south. Other brush species (e.g., Pseudomorus Brunoniana) have been found further to the south (Cambewarra Range), but have not yet been recorded near Bulli.
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(3). Sand-Dune Succession.
Consideration of sand-dune succession (psammosere), and the succession from subsaline lagoons (infra) must involve an account of recent movements of the strand- line. On a stable coast, both successions must ultimately reach a state of dynamic equilibrium between the upgrade tendencies of autogenic succession and the retrograde influences of wind action, marine erosion, and scouring by creeks. The district studied has no rivers discharging into the sea, so that the additional factor of the continual addition to the coast, of alluvium, may be neglected almost entirely.
It seems reasonably certain from other sources of information that the portion of coastline under consideration has been subjected, during the last 3,000 years, to a fall in sea-level of some 15 feet (see, e.g, Cotton, 1926). This has probably been gradual, extending over the whole period, and possibly continuing at the same rate, though evidence of this is lacking. In any event, this fall has converted shallow estuaries and bays into land-locked lagoons some feet above sea-level; on the outer side of these
BY CONSETT DAVIS. 25
lagoons are belts of dunes, possibly sand-bars of the former bays and estuaries. The lagoons reach the sea through breaks in these dunes, although difficulty of access to the sea usually maintains them at a level some feet above the sea; they are consequently not tidal or as saline as sea-water.
This slow allogenic action has given rise to new areas for plant colonization, and the vegetation of the dunes now appears to be reasonably stable, evidences of forward succession possibly referring to progress allowed by the more recent stages in the fall in sea-level. There is a certain amount of local retrogression, probably compensated by local succession in other sectors.
The zonation of the dune communities may thus be considered as a forward succession, probably brought to a standstill by the absence or extreme slowness of further change in the strand-line, and the inability of the pioneer stages of the vegetation to advance any further seaward (PI. iii, C).
The sand-dune communities may be listed as follow:
(1). Festuca litoralis-Spinifex hirsutus-Carex pumila Associes.
This is the first community to develop, or, in terms of space, the most seaward. The first two species are of regular occurrence, Carex pumila being less common; it is questionable whether it deserves to rank in the naming of the associes, although, in certain dunes studied by the author in southern Tasmania, it and Festuca were equally important in this stage, while Spinifex was absent. The therophyte, Cakile maritima, occurs in and just below this community.
Festuca is a tussock-plant, and is most important in holding the sand against wind erosion on colonized areas, often remaining on sand hummocks when the surrounding sand at that level has been removed. Spinifex, with creeping stolons, is more important as a colonist of new areas, or areas which have been eroded. The rdles of these two species may therefore be regarded as passive and active respectively, in regard to soil stabilization (Pl. iii, A and C). On account of its greater mobility, Spinifex usually extends some distance beyond the seaward limit of Festuca.
(2). Shrub-Dune.
This community is dominated by shrubs of Leptospermum laevigatum, Leucopogon Richei, and Acacia Sophorae (Uabill.) R.Br., with Banksia integrifolia in the shrub stage. The chamaephyte element (especially Mesembryanthemum aequilaterale and Hibbertia volubilis) occasionally forms a ‘mat’ stage extending seaward beyond the shrub line.
The shrub-dune represents the highest level of the dune area (PI. iii, B), the ground behind it falling in level to the next stage (dune forest). The following is a floristic list for the shrub-dune:
N: A, Leptospermum laevigatum, Leucopogon Richei; C, Banksia integrifolia (bush), Acacia Sophorae R.Br.; LC, Lantana camara (Cintrod.); O, Atriplex cinerewm, Monotoca scoparia, Senecio lautus; R, Correa alba.
Ch: C, Mesembryanthemum aequilaterale, Hibbertia volwbilis; O, Commelina cyanea, Rhagodia hastata, Tetragonia expansa, Pelargonium australe, Calystegia Soldanella R.Br.; R, Rhagodia baccata Mogq.
1208 C, Cynodon dactylon; O, Sporobolus virginicus, Scirpus nodosus, Dichondra repens ; R, Imperata cylindrica var. Koenigii, Lomandra longifolia Labill., Oxalis corniculata.
G: O, Pteridium aquilinum. ,
Th: O, Sonchus oleraceus (introd.), Onopordon Acanthiwm (introd.).
(3). Hucalyptus botryoides—Banksia integrifolia Associes.
On the inner slope leading down from the shrub-dune, and in sandy hollows still further from the sea, a forest dominated by Banksia integrifolia and Hucalyptus botryoides, usually some 40 feet in height, occurs. All elements of the shrub-dune stage occur in this forest, in approximately the same proportions. Hucalyptus longifolia and Banksia serrata occur rarely as low trees. Additional species include:
M: Pittosporum undulatum, Acacia linearis, Synoum glandulosum, Breynia oblongi- folia, Cupaniopsis anacardioides Radlk., Clerodendron tomentosum. M (climbers): Lyonsia straminea, Tylophora barbata.
26 PLANT ECOLOGY OF TIIE BULLI DISTRICT. III,
N: Sida vrhombifolia (occasionally chamaephytic), Pimelea linifolia, Brachyloma daphnoides. N (climbers): Geitonoplesium cymosum, Stephania hernandifolia.
Ch: Viola hederacea, Halorrhagis teucrioides. Ht: Themeda australis Stapf., Rubus fruticosus (introd.). BE: Cassytha paniculata.
No climax Mixed Hucalyptus Forest occurs on dune soils in this area.
Retrograde factors adversely influencing the succession are marine eresion (action of waves during storms on the outer parts of the Festuca-Spinifex-Carex stage); wind erosion or blow-outs affecting chiefly the pioneer stage, where the soil is least efficiently stabilized, but sometimes affecting the higher stages, e.g., dune forest, after the inter- mediate stages have been removed (cf. Pl. iii, D); swamping of vegetation by drifting sand loosened by the preceding factor (affecting the dune forest community on the inner slope of the dunes, and noted to occur in many parts of the area); and erosion by the waters of lagoons, when they effect outflow to the sea (cf. Pl. iii, HE). Opposed to these factors are the normal upgrade tendencies typical of any pSammosere, namely, soil stabilization by vegetational cover, and improvement of the soil (especially with regard to water-retaining capacity) by the addition of organic remains. Proof of retrogression in some sectors is a matter of direct observation; proof of forward succession in other areas is deduced from examination of soil profiles with an auger, the soil of all stages passing, with increase in depth, to dune sand, by decrease of the percentage of organic matter.
Properties of surface soils in this psammosere are listed in Tables 3 and 3a. They indicate the increasing water-retaining capacity of the sere, due to accumulation of organic remains. Hydrogen peroxide tests indicate that the ratio of humus content to loss on ignition is 5-8% for the Spinifex-Festuca-Carex stage, 40% for the shrub- dune, 50% or a little over for the dune forest. Variations in chloride content, and in water-content (Table 3A) seem to be due to differences in drainage and leaching, the Festuca hummocks and the shrub-dune, on the dune crest, being efficiently drained and leached, part of the chloride leached from the latter passing to the dune forest soil on the inner slope. The soil of the dune forest, with its higher water-retaining capacity, would be less affected by percolation and leaching. Spray incidence is probably not greatly different in the various stages, but the lowest parts of the Spinifex zone occasionally come under the effect of waves. There is scarcely any significant change in pH throughout the sere, probably because of the buffering action of salts.
TABLE 3. Sotl Properties for Sand-Dune Succession.
Loss on —— W.R.C. (%). Ignition (%). pH. Cl. (%)- Beach Sand .. 22 3-2* 6-6 0-05 Spinifex-Festuca Associes 24 0-6* 6-5 0-01 Spinifex 24 0:5* 6-3 0-11 25 1:9* 6:2 0-11 25 2-8* 6°7 0-01 27 3-3* 6-7 0-004 27 4-0* 6°5 0-02 Festuca 24 2-2* 6°5 0-005 27 1-2* 6:8 0-002 Shrub-Dune 28 2-67 6-9 0-01 29 2-2+ 6-8 0-01 31 0-9F 7-0 0-02 32 1-2 6-9 0:02 Eucalyptus botryoides-Banksia integrifolia 30 4:0 6-3 0-02 Associes me ae bee ae 32 2°9 6-6 0-02 36 4-2 6-6 0:02 50 5:5 6-1 0-03
Climax ts “4 0 ne ae Does not develop
BY CONSETT DAVIS. 724i
TABLE 3A. Soil Properties on Transect at North Towrodgie.
Loss on Water —— W.R.C. (%). Ignition (%). pH. Cle (%): Content (%). (14.7.38). Spinifex .. an ae 27 4-0* 6°5 0-03 3:3 Festuca (hummock) .. 24 2-2% 6°5 0-01 2-8 Shrub-dune sis ae 29 PACA 6:8 0-01 0-7 Dune Forest .. Be 30 4:0 6:3 0-02 2-9
* Almost entirely due to calcium carbonate. } Largely due to calcium carbonate.
(4). Subsaline Lagoon Succession.
This is a typical subsaline hydrosere, proceeding at the borders of the coastal lagoons whose formation by falling sea-level has been noted above. In general, forward succession in time seems to prevail, the allogenic causes of lagoon formation being too recent for any final equilibrium yet to have been reached. Retrogression by scouring is slight, and confined to the outer side of bends in the narrower parts of the lagoons, and especially at the lagoon mouths, where the outflow, though discontinuous, may some- times be rapid (e.g., immediately following the breaking of the sand-bar obstruction after a period when outflow has been cut off).
In general, the lagoon borders are flat, and in some cases rise rather gradually to drier ground with alluvial soil carrying Mixed Hucalyptus Forest, regarded as the climax of the sere. The immediate cause of the succession is the raising of soil level by alluvium and plant remains, probably aided by fall in lagoon level;* the resultant fall in water-table relative to the soil surface allows a lowering of humus content (Table 4). The pH falls, as the buffering by lagoon waters decreases, to a minimum in the Hucalyptus robusta Associes, and rises again as the conditions become finally drier. Soil properties are listed in Table 4; over 50%, sometimes almost 100%, of the figures for loss on ignition represent humus. The properties of the first stage (Phragmites) are not listed, being atypical of this stage in other districts (infra) ; the properties for the Cladium junceum stage are bracketed, as this community is absent from the lagoon (Towrodgie Lagoon) where the other samples, representing a transect, were collected. The sample for the Cladium junceum stage represents part of the community beside Bellambi Lagoon, where the salinity and water-level were temporarily in a different state from Towrodgie Lagoon at the time of sampling.
The stages may be listed as follow:
TABLE 4. Soil Properties for Subsaline Lagoon Succession.
Loss on Water —— W.R.C. (%). Ignition (%). pH. Gi, (9%). Content (%). (4.7.38). Juncus maritimus Associes ile 170 59 6-0 3-4 400 Cladium junceum Associes .. Ne (140) (48) (5-2) (1-9) (120) Casuarina glauca Associes .. As 140 50 4-6 2°8 220 Eucalyptus robusta Associes =. 140 47 3°4 0-45 33 Mixed Eucalyptus Forest (Climax). . 63-91 13-20 6-0-6°3 0-05-0-08 4-7 Melaleuca Communities : M. ericifolia, close to lagoon 87 18 6-1 0-32 120 margin. Melaleuca spp., several feet 39 6-9 BO 0-02 12 above level of lagoon .. 35 8-8 5:8 0-12 12
* Over a long period of time. The outlet system causes a considerable fluctuation in lagoon level from season to season, but this fluctuation cancels out as a cause of succession.
bo oo
PLANT ECOLOGY OF THE BULLI DISTRICT. III,
(1). Phragmites communis Associes.
The halt-submerged species Phragmites communis Trin. is not well developed in the lagoons studied, nor are the submerged or floating stages (Zostera nana, Ruppia maritima, and filamentous algae such as Cladophora). The factor limiting the greater development of Phragmites appears to be the high and often rapidly-changing salinity. The species becomes more prominent in the upper waters of these lagoons, but here the neighbouring vegetation has been so much altered by clearing that a full study was unprofitable. In these upper reaches, where the salinity is low, Triglochin procera, Alisma Plantago and Villarsia exaltata F.v.M. occur occasionally, growing half-submerged.
In the parts of Towrodgie and Bellambi Lagoons where the succeeding stages (cf. Table 4) were most fully studied, there are local sparse stands of Phragmites communis; the soil (submerged) has here a low organic content and a pH approximating to the lagoon water. It includes a high proportion of intrusive dune sand. In other regions, the soil of the Phragmites communis Associes has typically a very high organic content, the pH approximating to that of the surrounding water, usually high.
(2). Juncus maritimus Associes.
Juncus maritimus is well developed around the margins of the lagoons studied (Pl. iv, C). The soil of this stage is always water-logged, though covered with surface water only when the lagoon level is abnormally high. The organic content is high; humus content lowers the pH below that of lagoon water. The chloride content is usually high.
(3). Cladium junceum Associes.
On the flatter parts of lagoon margins, a definite belt of Cladium junceum R.Br. develops behind the Juncus maritimus Associes. The soil has a lower water-content, organic content, and pH than the preceding stage.
The following herbaceous species occur among the dominants of stages (2) and (3), and occasionally on parts of the lagoon margin lacking Cladium and Juncus: Salicornia australis, Spergularia rubra, Apium prostratum, Hydrocotyle vulgaris, Samolus repens, Dichondra repens, Wilsonia Backhousei, Lobelia anceps, Selliera radicans, Cotula coronopifolia, C. reptans.
At the lagoon mouths, on flats of dune sand flooded by lagoon water, over which sea-water occasionally gains entry to the lagoons during rough weather, several of these species (e.g., Apiwm prostratum, Hydrocotyle vulgaris) often become temporarily established in what may be considered an intermediate between psammosere and hydrosere.
(4). Casuarina glauca Associes.
With decreasing water-content, soils of the lagoon margin carry a low forest of Casuarina glauca. Surface soils of this community are periodically, deeper soils con- tinuously, water-logged. The pH, chloride content and organic content are slightly lower than in the preceding stages.
In addition to the dominant, Casuarina glauca, and the orchid, Dendrobium teretifolium, epiphytic on it, this stage possesses a ground layer of Juncus maritimus or Cladium junceum, together with some of the herbs of the preceding stages (e.g., Selliera radicans).
(5). Eucalyptus robusta Associes.
On drier soils, with somewhat reduced organic and chloride content, and with the lowest pH of the sere, a forest of Eucalyptus robusta develops, the trees being typically 40-50 feet in height. In typical parts of this stage, the ground layer is composed almost entirely of Gahnia psittacorum; occasionally, species relict from a previous stage (e.g., Cladium junceum) occur. In the dried parts of this associes, which may be regarded as an ecotone community, species of the climax community or of the Melaleuca Community (infra) enter.
BY CONSETT DAVIS. 29
(6). Climax.
With increasing efficiency of soil drainage, Mixed Hucalyptus Forest occurs. There is usually a rather abrupt rise in ground level of two feet or more between the preceding stage and this forest, which is interpreted as the climax. ‘There seems little doubt, however, that the soil is alluvial, and has been a swamp soil in the past. The facts may be explained by a rather sudden fall in lagoon level at some past time, instead of a gradual increase in soil level by the accumulation of soil and plant remains. The occurrence of trees characteristic of damper stages (Hucalyptus robusta, Melaleuca linarvifolia) at certain points within this forest does not appear to represent individual relics of an earlier stage as such; the time since the suggested fall in lagoon level would probably far exceed the life of any such tree. These trees may be regarded as relict species (not individuals), persisting where local conditions of drainage have remained in the earlier state.
The commonest trees of this forest are Hucalyptus longifolia and EH. punctata; E. botryoides, H. paniculata, E. eugenioides and E. pilularis are also frequent. H. robusta occurs locally in damper situations, e.g., in slight depressions. The trees are rather widely spaced, and usually only some 50 feet in height. ~Old trees of Melaleuca linariifolia, up to 30 feet in height, are scattered throughout the forest. The lower layers are strongly suggestive of the mixed forest on tuffaceous mudstone discussed earlier. They include species of the normal Hucalyptus pilularis Association, species of the earlier stages of the lagoon sere, brush or brush ecotone species, and, much more rarely, dune forest species.
The lower strata have been too much altered by clearing to justify an estimate of the frequency of component species. Below is a list of species classified under life- forms, and exclusive of