Vegetation Patterns of Eastern South Australia : Edaphic Control and Effects of Herbivory
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ì ,>3.tr .qF VEGETATION PATTERNS OF EASTERN SOUTH AUSTRALIA: EDAPHIC CONTROL &. EFFECTS OF HERBIVORY by Fleur Tiver Department of Botany The University of Adelaide A thesis submitted to the University of Adelaide for the degree of Doctor of Philosophy ar. The University of Adelaide (Faculty of Science) March 1994 dlq f 5 þø,.^roÅe*l *' -f; ri:.f.1 Frontispiece The Otary Ranges in eastern und is near the Grampus Range, and the the torvn of Yunta. The Pho TABLE OF CONTENTS Page: Title & Frontispiece i Table of Contents 11 List of Figures vll List of Tables ix Abstract x Declaration xüi Acknowledgements xiv Abbreviations & Acronyms xvü CHAPTER 1: INTRODUCTION & SCOPE OF THE STUDY INTRODUCTION 1 VEGETATION AS NATURAL HERITAGE 1 ARID VEGETATION ) RANGELANDS 3 TTTE STUDY AREA 4 A FRAMEWORK FOR THIS STUDY 4 CONCLUSION 5 CHAPTER 2: THE THEORY OF VEGETATION SCIENCE INTRODUCTION 6 INDUCTTVE, HOLIS TIC, OB S ERVATIONAL & S YNECOLOGICAL VERSUS DEDU CTIVE, EXPERIMENTAL, REDUCTIONI S T & AUTECOLOGICAL RESEARCH METHODS 7 TT{E ORGANISMIC (ECOSYSTEM) AND INDIVIDUALISTIC (CONTINUUM) CONCEPTS OF VEGETATION 9 EQUILIBRruM & NON-EQUILIBRruM CONTROL OF VEGETATON PATTERNS T3 EQUILIBRruM VS STATE-AND-TRANSITON MODELS OF VEGETATON DYNAMICS 15 CONCLUSIONS 16 11 CHAPTER 3: METHODS IN VEGETATION SCIENCE INTRODUCTION t7 ASPECT & SCALE OF VEGETATION STUDIES t7 AUTECOT-OGY Crr-rE STUDY OF POPULATTONS) & SYNEC:OLOGY (TI{E STUDY OF CTfMML'NTTTES) - A QUESTION OF SCALE l8 AGE-CLASS & STAGE-CLASS DISTRIBUTIONS IN POPULATION STUDIES t9 NUMERICAL (OBJECTIVE) VS DES CRIPTIVE (SUBJECTTVE) TECHNIQUES 20 PHYSIOGNOMIC & FLORISTIC METHODS OF VEGETATION CLASSIFICATON 22 SCALE OF CLASSIFICATION 24 TYPES OF ORDINATON 26 CIOMBINATION OF CLASSIFICATION & ORDINATION (COMPLEMENTARY ANALY SIS ) 27 CONCLUSIONS 28 CHAPTER 4: STUDY AREA . PHYSICAL & CLIMATIC CHARACTERISTICS INTRODUCTION 30 LANDFORMS 30 GEOI.OGY 3I SOILS 33 CLIMATE Temperature 34 Rainfall 35 CLIMATC & EDAPHIC CONTROL OF VEGETATION 38 CONCLUSIONS 4l CHAPTER 5: STUDY AREA . BIOTA INTRODUCTION 42 EARLY ACCOUNTS OF TT{E PHYTOGEOGRAPHY OF SOUTH AUSTRALIA 42 PALAEOBOTANICAL EVIDENCE OF PAST VEGETATION 44 CHARACTERISTICS OF AUSTRALIAN ARID VEGETATON 46 111 VEGETATON MAPS 49 NUMEzuCAL FLOzuSTC STUDTES 52 NATIVE VERTEBRATE F{ERBIVORES 52 LAND USE 53 The Aboriginal people 53 European settlement and pastoralism 55 FERAL & EXOTIC T{ERBIVORES & THEIR EFFECTS ON VEGETATION 58 INCREASING POPULATIONS OF NATIVE SHRUBS ("WOODY \ryEEDS'') 62 C]CNSERVATION 63 DISCUSSION & CHAPTER 6: PERBNNIAL VEGETATION PATTERNS . ALLIANCES INTRODUCTION 65 METHODS Survey & sampling strategy 66 Relative abundance 70 ANALYSIS METFIODS 7l Cluster analysis 73 Indirect ordination 75 RESULTS Vegetation alliances & distribution maps 75 DISCUSSION 78 Mapping techniques t9 Comparison with previous vegetation maps 80 CONCLUSIONS CHAPTER 7: PERENNIAL VEGETATION PATTERNS . ASSOCIATIONS INTRODUCTION 82 METIIODS Sampling strategy 82 Estimation of percentage cover 85 ANALYSIS METHODS Cluster analysis 86 lv Indirect ordination 87 Chi-square comparisons of groupings 88 RESULTS Vegetation associations 88 DISCUSSION Significance to theory & methodology of vegetation science 90 Relationship to previous classifications 92 Relationship of associations to alliances 93 CONCLUSIONS CHAPTER 8: VARIABLES CONTROLLING PERENNIAL VEGETATION DISTRIBUTION INTRODUCTION 95 METHODS Major environmental variables 96 Macro and micro-scale edaphic variables 96 ANALYSIS METTIODS Canonical correspondence analysis 98 Direct correlations (pearson correlation coefficients) 100 Multiple regressions 101 RESULTS Overview r02 Variables associated with major floristic differences 104 DISCUSSION 107 CONCLUSIONS 108 CHAPTER 9: PERENNIAL POPULATION DYNAMICS INTRODUCTION 110 METHODS Stratification of grazing levels tt2 Collection of population data tt4 Collection of environmental data 118 ANALYSIS METHODS r20 RESULTS Multicollinearity of variables t2t Correlation of recruitment & regeneration with graz\ng & environmen tal variables 122 Grazing by herbivores t23 Species unaffected or promoted by grazing t2s Edaphic variables affecting recn¡itment & regeneration t26 Lack of correlation between recruitment & regeneration 126 Lack of regeneration not attributable to graùLng 127 DISCUSSION Relative effects of domestic & non-domestic herbivores r27 "Vy'oody weeds" 129 Differences between recruitment & regeneration 13t Edaphic variables & regeneration 132 Importance of historical events r33 CONCLUSIONS 134 CHAPTER 10: GENERAL DISCUSSION INTRODUCTION t36 IMPORTANCE OF RESULTS TO ARID-ZONE ECOLOGY & VEGETATION SCIENCE Methods in vegetation science t36 The nature of vegetation 138 The climax theory of vegetation t39 Evidence for the state-and-transition model of vegetation dynamics r39 IMPORTANCE OF RESULTS TO CONSERVATION & MANAGEMENT Representativeness of areas conserved 140 "Woody weeds" t42 S ustainability of pastoralism r42 Vegetation description t43 CONCLUSIONS 143 APPENDICES APPENDIX 1: Plant species of eastern South Australia APPENDIX 2: Summary of vegetation alliances & associations APPENDIX 3: Photographs of vegetation associations REFERENCES vl LIST OF FIGURES Following Page: Figure 1.1 l-ocation of the study area 4 Figure 4.1 Topography and drainage system of the study area 30 Figtre 4.2 Geology of the study area 30 Figure 4.3 Soils of the study area 33 Figure 4.4 Annual rainfall for Yunta, South Ausralia from 1888 - 1993 35 Figure 4.5 Monthly median rainfall for Yunta, South Australia 35 Figure 4.6 Median annual rainfall for the study area 37 Figure 5.1 Vegetation of the study area after Prescott,1929 49 Figure 5.2 Vegetation regions of the study area after Wood, L937 50 Figure 5.3 Vegetation types of the study area after Wood, 1937 50 Figure 5.4 Vegetation of fa¡-western NSW after Beadle, 1945 50 Figure 5.5 Vegetation of the study area after Specht,1972 51 Figure 5.6 Pastoral leases of the study area circa 1860 55 Figure 5.7 Pastoral leases ofthe study area círca1867 55 Figure 5.8 Pastoral leases of the study area after SADENR, 1993 63 Figure 6.1 Sampling strategy for identifying vegetation alliances 68 Figure 6.2 Summary dendrogram of floristic alliances of the study area 75 Figure 6.3 Floristic vegetation alliances of the study area (map) 75 Figure 6.4 Detrended correspondence analysis of full strip-census data 75 Figure 6.5 Detrended correspondence analysis of srip-census data, with Alliances I, VIII and X removed 77 Figure 7.1 Summary dendrogram of floristic associations of the study area 88 Figure7.2 Floristic vegetation associations of the study area (map) 88 Figure 7.3 Detrended correspondence analysis of floristic data from all205 sites 89 Figure 7.4 Detrended correspondence analysis of floristic data, omining Vegetation Associations A and R 89 vl1 Figure 8.1 Plexus diagram showing degree of multicollinearity of variables used in DCCA analysis r02 Figure 8.2a DCCA of association data; all sites and all variables 103 Figure 8.2b DCCA of association data with Associations A, B, G, H and I r03 removed Figure 8.2c DCCA of association data with Associations A, B, G, H, I, D, C and R removed 103 Figure 9.1 Nine life-stage classes recognizable in woody perennial plant species tt4 Figure 9.2 Plexus diagram showing relationships of variables susp€cted of affecting recruitment and regeneration 121 vlll LIST OF TABLES Following Page: Table 6.1 Scale for estimating relative abundance of perennial species along the strip-census 70 Table6.2 Synoptic table of floristic alliances from survey data 75 Table 7.1 Comparison of the cover scale used in this study with other scales existing in the literature 80 Table7.2 Synoptic table of indicator species of floristic associations from site-based survey data 89 Table 7.3 Chi-square contingency table of the distribution of vegetation associations across vegetation alliances 89 Table 8.1 Ordinal scaling of environmental variables used for DCCA analysis 96 Table 8.2 Summary of climatic and edaphic variables used in DCCA analysis 98 Table 8.3 Association matrix of climatic and edaphic variables toz Table 8.4 Results of multiple regressions 103 Table 9.1 Woody perennial species which occasionally occur in the landscape at very low frequency lt4 Table9.2 Ordinal classes for environmental variables 118 Table 9.3 Pearson correlation coefficients of variables suspected of affecting recruitment and regeneration in woody perennial plants l2r Table 9.4 Pearson correlation coefficients of grazing and environmental variables to p€rcentage recruitment of juveniles r22 Table 9.5 Pearson correlation coefficients of grazing and environmental variables to percentage regeneration t22 Table 9.6 Variables contributing to the species models of percentage recruiünent t22 Table 9.7 Variables contributing to the species models of percentage regeneration t22 Table 9.8 Comparison of regeneration between grazed and non or very lightly grazed sites t22 Table 9.9 Summary of species significantly and negatively affected by grazing-related variables 122 Table 9.10 Summary of species unaffected by or positively related to grazing-related variables t22 1X ABSTRACT The short time since European settlement and commencement of pastoralism in the Australian arid lands means that the vegetation is of signihcant heritage value. It also represents a unique opportunity to document the effects of domestic herbivores on a¡id vegetation. Methods for rapidly describing the vegetation, the variables controlling patterns within it, and the effects of domestic herbivores are therefore useful in other large,