Impacts of climate change and environmental factors on the potential distribution of two invasive acacia species analysing current patterns and predicting future scenarios in au

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY ALEISA HANNAH TADIOS AYSON IMPACTS OF CLIMATE CHANGE AND ENVIRONMENTAL FACTORS ON THE POTENTIAL DISTRIBUTION OF TWO INVASIVE ACACIA SPECIES: ANALYSING CURRENT PATTERNS AND PREDICTING FUTURE SCENARIOS IN AUSTRALIA BACHELOR THESIS Study Mode: Major: Faculty: Batch: Full-time Environmental Science and Management Advance Education Program 2015 - 2018 Thai Nguyen, 25/09/2018 Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student Name Aleisa Hannah Tadios Ayson Student ID DTN1554290046 Thesis Title Impacts of Climate Change and Environmental Factors on the Potential Distribution of two Invasive Acacia species: Analysing Current Patterns and Predicting Future Scenarios in Australia Supervisors Supervisors’ signature Abstract: Dr Eddie van Etten and Dr Do Thi Ngoc Oanh Invasive species and climate change interact in a positive feedback loop and are identified as drivers of global change which impose impacts on ecological systems This study aimed (i) to determine the potential invasion pattern of A longifolia subsp longifolia and A, iteaphylla based on climatic and environmental factors in Australia, (ii) to determine the potential future invasion pattern of both Acacia species with climate change and (iii) to determine the effect of environmental factors (distance, depth to groundwater, understorey cover, fire and occurrence of larger trees) on the local-scale patterns of invasion of the two Acacia species in Perth, Western Australia (WA) Species Distribution Modelling (SDM) was done to project the potential invasion pattern of the two Acacia species for current and future periods using the Atlas of Living Australia (ALA) and Biodiversity Climate Change Virtual Laboratory (BCCVL) In order to determine the effect of environmental factors on the local-scale patterns of invasion of the two Acacia species, a field survey was done on the Swan Coastal Plain, Perth, WA The current potential distribution range of A longifolia subsp longifolia based on its natural and naturalised distributions in Western (WA), South (SA) and East Australia (EA) under climate variables will contract as affected by the influence of environmental variables while the potential distribution of A iteaphylla based on its natural and naturalised distribution in WA, SA, and EA will expand in distribution range once environmental variables were added A longifolia subsp longifolia will ii continue to expand distribution to southern EA and Tasmania in the future under RCP 4.5 and will continuously expand under RCP 8.5; A iteaphylla will cease to expand and will start to decrease in density in all its ranges in WA, SA, and EA under RCP 4.5 and will continuously contract in RCP 8.5 Field survey results showed that A longifolia subsp longifolia grew more on undisturbed wet areas while A iteaphylla grew more on well disturbed dry areas Burnt sites showed a higher density of A longifolia subsp longifolia plants (472) than the unburnt sites (55) Both species have shown a similar preference for occurring under larger trees Results from both SDM and field survey showed the different response of the two Acacia species on climate and environmental factors Keywords: Acacia longifolia subsp longifolia, Acacia iteaphylla, invasive species, species distribution model, climate change, invasion patterns Number of page 193 Date of submission September 25, 2018 iii ACKNOWLEDGEMENT The writing of this bachelor’s degree thesis was not an easy task During the time of writing, the researcher received support and help from various people and institutions First and foremost, praises and thanks to God for His showers of blessings throughout the completion of this study The researcher would like to share her deepest gratitude to the Advanced Education Program and to the TUAF officials for their unending assistance to their students The researcher is also grateful to the School of Science of Edith Cowan University whose research travel grant made the field work possible The researcher is profoundly indebted to both her supervisors Sincerest thanks to Dr Eddie van Etten for his warmest welcome, generosity of time, knowledge and resources, and for assisting the researcher in each step of the thesis most especially in her field works Appreciation is given to Dr Do Thi Ngoc Oanh for her patient guidance, encouragement, and advice given to the researcher throughout the thesis writing Completing this work would have been more difficult were it not for the support and friendship provided by the amazing people that the researcher met in Australia that made her stay there beyond great Deepest gratitude to her family and friends who never failed to give an indispensable source of support and encouragement Finally, the researcher extends her regards to all of those who supported her in any respect during the completion of this study Thanks for everything that helped the researcher get to this day Aleisa Hannah T Ayson iv TABLE OF CONTENTS LIST OF TABLES xi LIST OF ABBREVIATIONS xii PART I INTRODUCTION 13 1.1 Research Rationale 13 1.2 Research’s Objectives 19 1.3 Research Questions and Hypotheses 19 1.4 Limitations 23 1.5 Definitions 24 PART II LITERATURE REVIEW 26 2.1 Species invasion 26 2.1.1 Impacts of species invasion 26 2.1.2 Drivers of species invasion 27 2.1.2.1 Climate change 27 2.1.2.2 Characteristics of species 28 2.1.2.3 Environmental factors 29 2.1.3 Invasion patterns of weedy plants in Australia 32 2.2 Acacia species 33 2.2.1 Acacia longifolia and its subspecies 35 2.2.2 Acacia iteaphylla 38 2.2.3 Acacia as invasive species 40 2.2.3.1 Invasion of Acacia species: Global 40 2.2.3.2 Invasion of Acacia species: Australia 42 2.2.3.3 Invasion of Acacia species in the Perth region, Western Australia 44 2.2.4 Seed dispersal of Acacia 44 2.2.5 Fire response of Acacia 46 2.3 Background on methods used in biodiversity study 48 2.3.1 Species Distribution Models and invasive species: 48 2.3.1.1 Biological Data 50 2.3.1.2 Environmental Data 50 ii 2.4.2 Invasion patterns at local-scale 52 PART III: METHODS 54 3.1 Materials 54 3.2 Site selection 63 3.3 Field survey and data collection 64 3.4 Statistical analyses 66 PART IV: RESULTS AND DISCUSSIONS 68 4.1 Invasion patterns of A longifolia subsp longifolia and A iteaphylla in Australia 68 4.1.1 Invasion patterns in Australia: Climate change factors 68 4.1.2 Current distribution of A longifolia subsp longifolia and A iteaphylla in Australia 68 4.1.3 Invasion patterns in Australia: Environmental factors 72 4.1.4 Current distribution of A longifolia subsp longifolia and A iteaphylla due to environmental variables in Australia 72 4.1.5 Potential range expansion in future distribution of A longifolia subsp longifolia and A iteaphylla due to climate change in Australia 75 4.1.6 Prediction accuracy of Species Distribution Models of A longifolia subsp longifolia and A iteaphylla 86 4.1.7 Significant variables used in the Species Distribution Model of A longifolia subsp longifolia and A iteaphylla under current conditions 87 4.1.8 Mean response curves of the potential current predictions of A longifolia subsp longifolia and A iteaphylla 89 4.2 Local-scale patterns of invasion of A longifolia subsp longifolia and A iteaphylla in Perth, WA: Environmental Factors 98 4.2.1 Edge effect on plant density, basal area and biovolume of A longifolia subsp longifolia and A iteaphylla 98 4.2.2 Effect of depth to groundwater to plant density of A longifolia subsp longifolia and A iteaphylla 109 4.2.3 Effect of different understorey cover on the occurrence of A longifolia subsp longifolia and A iteaphylla 112 4.2.4 Effect of fire on the plant density, basal area and biovolume of A longifolia subsp longifolia 113 iii 4.2.5 Effect of occurrence of larger trees on occurrence of A longifolia subsp longifolia and A iteaphylla 114 4.3 Discussion 116 4.3.1 Invasion patterns in Australia: SDM using climate and environmental variables 116 4.3.2 Invasion patterns in Perth, WA: Environmental factors in field survey 122 PART V: CONCLUSIONS AND RECOMMENDATIONS 128 5.1 Conclusions 128 5.2 Recommendations 130 REFERENCES 132 APPENDICES 151 iv LIST OF FIGURES Figure 1: Predicted current distribution of A longifolia subsp longifolia based on its native ranges under current climate condition produced in BCCVL Darker areas representing a higher likelihood that the species can occur 69 Figure 2: Predicted current distribution of A longifolia subsp longifolia based on its naturalised ranges under current climate condition produced in BCCVL Darker areas representing a higher likelihood that the species can occur 69 Figure 3: Predicted current distribution of A iteaphylla based on its native ranges under current climate condition produced in BCCVL Darker areas representing a higher likelihood that the species can occur 70 Figure 4: Predicted current distribution of A iteaphylla based on its naturalised ranges under current climate condition produced in BCCVL Darker areas representing a higher likelihood that the species can occur 71 Figure 5: Predicted current distribution of A longifolia subsp longifolia based on its native ranges under current climate and environmental variables produced in ALA (see legend for species occurrence probability) White dots show the presence locations used for training, while violet dots show test locations 73 Figure 6: Predicted current distribution of A longifolia subsp longifolia based on its naturalised ranges under current climate and environmental variables produced in ALA (see legend for species occurrence probability) White dots show the presence locations used for training, while violet dots show test locations 73 Figure 7: Predicted current distribution of A iteaphylla based on its native ranges under current climate and environmental variables produced in ALA (see legend for species occurrence probability) White dots show the presence locations used for training, while violet dots show test locations 74 Figure 8: Predicted current distribution of A iteaphylla based on its naturalised ranges under current climate and environmental variables produced in ALA (see legend for species occurrence probability) White dots show the presence locations used for training, while violet dots show test locations 75 Figure 9: a) Predicted future distribution map and b) change in potential species change map of A longifolia subsp longifolia based on its native range projected to the year 2045 using RCP 4.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas v marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 77 Figure 10: a) Predicted future distribution map and b) change in potential species change map of A longifolia subsp longifolia based on its native ranges projected to the year 2045 using RCP 8.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 78 Figure 11: a) Predicted future distribution map and b) change in potential species change map of A longifolia subsp longifolia based on its naturalised ranges projected to the year 2045 using RCP 4.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 79 Figure 12: a) Predicted future distribution map and b) change in potential species change map of A longifolia subsp longifolia based on its naturalised ranges projected to the year 2045 using RCP 8.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 80 Figure 13: a) Predicted future distribution map and b) change in potential species change map of A iteaphylla based on its native ranges projected to the year 2045 using RCP 4.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 82 Figure 14: a) Predicted future distribution map and b) change in potential species change map of A iteaphylla based on its native ranges projected to the year 2045 using RCP 8.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer vi to change in species map for the detailed potential distribution in the future 83 Figure 15: a) Predicted future distribution map and b) change in potential species change map of A iteaphylla based on its naturalised ranges projected to the year 2045 using RCP 4.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 84 Figure 16: a) Predicted future distribution map and b) change in potential species change map of A iteaphylla based on its naturalised ranges projected to the year 2045 using RCP 8.5 to influence the CSIRO Mark 3.0 with 30” resolution Areas marked red in the future projection map represents where species will disappear from the current distribution and areas marked green represents where will species occur Refer to change in species map for the detailed potential distribution in the future 85 Figure 17: The response curves of A longifolia subsp longifolia under climate variables based on its native ranges where: B17-precipitation of driest quarter, B05max temperature of warmest week, B08-mean temperature of wettest quarter, B12annual precipitation, B18-precipitation of warmest quarter and B19-precipitation of coldest quarter X-axis refers to levels of variables and Y-axis refers to probability of occurrence 90 Figure 18: The response curves for A longifolia subsp longifolia with added environmental variables based on its native ranges where: el647-remoteness index, el864-moisture index (driest quarter), el870-mean temperature of warmest quarter, el873-mean moisture index of coldest quarter, el879-max temperature of warmest week, el885-moisture index seasonality, el889-precipitation of driest quarter, el891annual mean moisture index, el893-annual precipitation, and el895-lowest weekly moisture index X-axis refers to levels of variables and Y-axis refers to probability of occurrence 91 Figure 19: The response curves of A longifolia subsp longifolia under climate variables based on its naturalised ranges where: B08-mean temperature of warmest quarter, B14-precipitation of driest week, B05-max temperature of warmest week, B04-temperature seasonality and B19-precipitation of coldest quarter X-axis refers to levels of variables and Y-axis refers to probability of occurrence 92 Figure 20: The response curves for A longifolia subsp longifolia based on its naturalised ranges with added environmental variables where: el819-distance to coast, el863-precipitation of coldest quarter, el870-mean temperature of wettest quarter, vii Appendix 11: Fire history map of southern wetlands in Perth 176 Appendix 12: Illustration on the difference between understorey plants and tree species Any tree species Acacia plant Understorey plants Note: Any tree species that covered the Acacia plant was counted as a tree, while every plant that was below and surrounded the Acacia plant was included in the estimation of understorey cover 177 Appendix 13: Table of variables used to influence the models Bioclim Variable Description Code Code Bio01 el874 Annual mean temperature (°C) Mean diurnal temperature range (mean (period max-min)) Bio02 el888 (°C) Bio03 el883 Isothermality (Bio02 ÷ Bio07) Bio04 el892 Temperature seasonality (C of V) Bio05 el879 Max temperature of warmest week (°C) Bio06 el867 Min temperature of coldest week (°C) Bio07 el862 Temperature annual range (Bio05-Bio06) (°C) Bio08 el870 Mean temperature of wettest quarter (°C) Bio09 el875 Mean temperature of driest quarter (°C) Bio10 el890 Mean temperature of warmest quarter (°C) Bio11 el876 Mean temperature of coldest quarter (°C) Bio12 el893 Annual precipitation (mm) Bio13 el866 Precipitation of wettest week (mm) Bio14 el872 Precipitation of driest week (mm) Bio15 el882 Precipitation seasonality (C of V) Bio16 el886 Precipitation of wettest quarter (mm) Bio17 el889 Precipitation of driest quarter (mm) Bio18 el878 Precipitation of warmest quarter (mm) Bio19 el863 Precipitation of coldest quarter (mm) Bio28 el891 Annual mean moisture index Bio29 el884 Highest weekly moisture index Bio30 el895 Lowest weekly moisture index Bio31 el885 Moisture index seasonality (C of V) Bio32 el865 Mean moisture index of wettest quarter Bio33 el864 Mean moisture index of driest quarter Bio34 el868 Mean moisture index of warmest quarter Bio35 el873 Mean moisture index of coldest quarter el816 Soil depth el823 Erosional surfaces - proportion el814 Clay % el806 Bulk density el647 Remoteness index el830 Distance - to permanent water (weighted) el819 Distance - to coast 178 Appendix 14: Edge effect on the plant density of A longifolia subsp longifolia in unburnt sites Plant Density (plants/ha) Location site Overall Plant Density (all sites) (plants/ha) Thomsons *Overall Plant Standard Lake *Anketell *De Haer Density *Piara Error Nature Road Road (n=55) (n=5) Reserve (n=12) (n=6) (n=10) 0-9 60 200 133.33 40 86.67 31.89 10-19 100 166.67 66.67 60 78.67 24.40 20-29 80 20 0 20 13.86 30-39 20 0 20 4.38 40-49 40 33.33 0 14.67 8.09 50-59 20 40 0 12 7.16 60-69 120 80 0 40 22.63 70-79 40 20 12 7.16 80-89 0 0 0 90-99 100 20 0 24 17.34 r-value 0.06 0.03 0.68 0.46 0.44 0.42 p-value 0.24 0.543 0.02 0.03 0.04 0.02 Note: The coefficient of determination (r) from regression analysis for the plant density of A longifolia subsp longifolia in unburnt sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population Dispersal Distance (m) Thomsons Lake Nature Reserve (n=22) 179 Appendix 15: Edge effect on the basal area of A longifolia subsp longifolia in unburnt sites Basal Area (m2/ha) Location Site Overall Basal Area (all sites) (m2/ha) Dispersal Distance (m) *Overall Basal Thomsons Thomsons Standard *Anketell *De Haer Area Lake Nature Lake Nature *Piara Error Road Road (n=55) Reserve Reserve (n=5) (n=12) (n=6) (n=22) (n=10) 0-9 0.17 0.17 0.44 0.09 0.17 0.07 10-19 1.32 1.57 0.24 0.12 0.65 0.29 20-29 1.12 0.37 0 0.30 0.20 30-39 0.10 0 0 0.02 0.02 40-49 1.49 0.32 0 0.36 0.26 50-59 0.02 0.66 0 0.14 0.12 60-69 4.06 1.56 0 1.13 0.71 70-79 0.26 0 0.05 0.05 80-89 0 0 0 90-99 1.89 0.02 0 0.38 0.34 r-value 0.04 0.02 0.91 0.47 0.45 0.002 p-value 0.36 0.57 0.62 0.03 0.03 0.90 Note: The coefficient of determination (r) from regression analysis for the basal area of A longifolia subsp longifolia in unburnt sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 180 Appendix 16: Edge effect on the biovolume of A longifolia subsp longifolia in unburnt sites Biovolume (m3/ha) Location Site Overall Biovolume (all sites) (m3/ha) Dispersal Distance (m) Overall Thomsons Thomsons Standard Anketell *De Haer Biovolume Lake Nature Lake Nature *Piara Error Road Road (n=55) Reserve Reserve (n=5) (n=12) (n=6) (n=22) (n=10) 0-9 717.78 1239.15 3740.46 1445.13 1428.50 563.10 10-19 5501.79 1394.08 1796.60 1189.88 1976.47 832.46 20-29 7711.98 1979.20 0 1938.24 1335.79 30-39 270.18 0 0 67.54 52.32 40-49 11885.71 206.17 0 2418.37 2117.26 50-59 1240.54 9927.43 0 2233.59 1733.76 60-69 51556.68 18566.81 0 14024.70 8987.45 70-79 5112.94 0 1278.24 990.12 80-89 0 0 0 90-99 18189.04 314.16 0 3700.64 3240.16 r-value 0.01 0.01 0.63 0.46 0.49 0.04 p-value 0.69 0.75 0.11 0.03 0.02 0.57 Note: The coefficient of determination (r) from analysis for the biovolume of A longifolia subsp longifolia in unburnt sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 181 Appendix 17: Edge effect on the plant density of A longifolia subsp longifolia in burnt sites Plant Density Overall Plant Density (all sites) (plants/ha) (plants/ha) Location Site Overall Plant *Shirley Balla Shirley Balla Dispersal Density Standard Error Swamp Reserve Swamp Reserve Forrestdale Distance (m) (n = 472) (n = 208) (n = 74) (n = 190) 0-9 1066.67 366.67 477.78 255.48 10-19 266.67 366.67 133.33 255.56 55.18 20-29 100 300 533.33 311.11 102.24 30-39 33.33 633.33 2466.67 1044.44 597.59 40-49 133.33 200 1500 611.11 363.23 50-59 166.67 300 155.56 70.86 60-69 300 166.67 833.33 433.33 166.30 70-79 400 366.67 166.67 311.11 59.49 80-89 566.67 366.67 300 411.11 65.42 90-99 666.67 2700 333.33 1233.33 603.90 r-value 0.63 0.04 0.03 0.09 p-value 0.01 0.57 0.63 0.41 Note: The coefficient of determination (r) from regression analysis for the plant density of A longifolia subsp longifolia in burnt sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 182 Appendix 18: Edge effect on the basal area of A longifolia subsp longifolia in burnt sites Basal Area Overall Basal Area (all sites) (m /ha) (m2/ha) Location Site Dispersal Distance Overall Basal Area Shirley Balla Shirley Balla Standard Error Forrestdale (m) (n = 472) Swamp Reserve Swamp Reserve (n = 208) (n = 74) (n = 190) 0-9 0.13 0.65 0.26 0.16 10-19 0.18 0.09 0.05 0.11 0.03 20-29 0.02 0.10 0.25 0.12 0.06 30-39 0.12 0.81 0.31 0.21 40-49 0.04 0.34 0.90 0.43 0.21 50-59 0.14 0.18 0.10 0.04 60-69 0.28 0.17 0.32 0.26 0.04 70-79 0.13 0.31 0.11 0.18 0.05 80-89 0.11 0.19 0.30 0.20 0.05 90-99 0.10 1.19 0.22 0.50 0.28 r-value 0.12 0.26 0.09 0.13 p-value 0.34 0.11 0.39 0.31 Note: The coefficient of determination (r) from regression analysis for the basal area of A longifolia subsp longifolia in burnt sites with regards to distance from the edge of bushlands (α=0.05) Standard error values are the standard deviation of the population 183 Appendix 19: Edge effect on the biovolume of A longifolia subsp longifolia in burnt sites Biovolume Overall Biovolume (all sites) (m3/ha) (m3/ha) Location Site Dispersal Distance Overall Biovolume Shirley Balla Shirley Balla Standard Error Forrestdale (m) (n = 472) Swamp Reserve Swamp Reserve (n = 208) (n = 74) (n = 190) 0-9 924.34 4820.38 1914.91 1206 10-19 3501.33 815.06 209.44 1508.61 825.95 20-29 100.14 936.46 1342.90 793.16 298.71 30-39 6.54 1008.92 5062.96 2026.14 1262.09 40-49 460.19 1573.94 5822.81 2618.98 1334.04 50-59 446.50 1227.18 557.89 292.80 60-69 1673.08 1365.15 2779 1939.08 350.49 70-79 803.88 1732.33 1214.75 1250.32 219.32 80-89 706.91 1266.85 2524.98 1499.58 438.93 90-99 763.77 6370.57 1590.43 2908.26 1426.85 r-value 0.01 0.20 0.06 0.05 p-value 0.83 0.17 0.51 0.54 Note: The coefficient of determination (r) from regression analysis for the biovolume of A longifolia subsp longifolia in burnt sites with regards to distance from the edge of bushlands (α=0.05) Standard error values are the standard deviation of the population 184 Appendix 20: Edge effect on the plant density of A iteaphylla in surveyed sites Plant Density Overall Plant Density (all (plants/ha) sites) (plants/ha) Location Site Dispersal Canning *Overall Wandi Standard *De Haer *De Haer Battersb Neerabu Neerabu Distance Plant Density Vale Nature Error Road Road y Road p1 p2 (m) (n = 46) Road Reserve (n = 2) (n = 2) (n = 2) (n = 23) (n = 3) (n = 3) (n = 11) 0-9 60 20 20 60 60 20 34.29 8.77 10-19 20 20 200 380 88.57 51.56 20-29 0 0 20 40 8.57 5.51 30-39 0 0 20 0 2.86 2.65 40-49 0 0 0 0 50-59 0 0 0 0 60-69 0 0 0 0 70-79 0 0 20 0 2.86 2.65 80-89 0 0 0 0 90-99 0 0 0 0 r-value 0.27 0.48 0.48 0.31 0.01 0.26 0.27 0.39 p-value 0.12 0.03 0.03 0.09 0.81 0.13 0.13 0.05 Note: The coefficient of determination (r) from regression analysis for the plant density of A iteaphylla in all surveyed sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 185 Appendix 21: Edge effect on the basal area of A iteaphylla in surveyed sites Basal Area Overall Basal Area (all sites) (m2/ha) (m2/ha) Location Site Dispersal Canning *Overall *De *De Wandi Standard Battersb Neerabu Neerabu Distance Basal Area Vale Haer Haer Nature Error y Road p1 p2 (m) (n = 46) Road Road Road Reserve (n = 2) (n = 23) (n = 3) (n = 3) (n = 2) (n = 2) (n = 11) 0-9 0.42 0.19 0.10 0.07 0.20 0.63 0.23 0.08 10-19 0.06 0.06 0.01 1.72 0.26 0.23 20-29 0 0 0.04 0.03 0.01 0.01 30-39 0 0 0.20 0 0.03 0.03 40-49 0 0 0 0 50-59 0 0 0 0 60-69 0 0 0 0 70-79 0 0 0.29 0.05 0.04 80-89 0 0 0 0 90-99 0 0 0 0 r-value 0.27 0.41 0.47 0.33 0.02 0.23 0.29 0.48 p-value 0.12 0.05 0.03 0.08 0.68 0.17 0.11 0.01 Note: The coefficient of determination (r) from regression analysis for the basal area of A iteaphylla in all surveyed sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 186 Appendix 22: Edge effect on the biovolume of A iteaphylla in surveyed sites Biovolume (m3/ha) Overall Biovolume (all sites) (m3/ha) Location Site Dispersal Canning *Overall Wandi Standard De Haer De Haer Battersby Neerabup Neerabup Distance Biovolume Vale Nature Error Road Road Road (m) (n = 46) Road Reserve (n = 2) (n = 2) (n = 2) (n = 23) (n = 3) (n = 3) (n = 11) 0-9 2115.78 424.12 753.9822 403.88 916.95 673.48 755.46 234.19 10-19 62.83185 163.36 18.88 8623.28 1266.91 1135.30 20-29 0 0 125.66 70.87 32.76 18.50 30-39 0 0 1663.08 0 277.18 234.26 40-49 0 0 0 0 50-59 0 0 0 0 60-69 0 0 0 0 70-79 0 0 1849.46 0 308.24 260.51 80-89 0 0 0 0 90-99 0 0 0 0 r-value 0.27 0.34 0.37 0.30 0.01 0.22 0.31 0.42 p-value 0.12 0.08 0.06 0.10 0.77 0.17 0.10 0.04 Note: The coefficient of determination (r) from regression analysis for the biovolume of A iteaphylla in all surveyed sites with regards to distance from the edge of bushlands (α=0.05) Sites marked with “*” showed significant evidence of edge effect (i.e High r-value value and p-value ≤ 0.05 Standard error values are the standard deviation of the population 187 Appendix 23: The plant density of A longifolia subsp longifolia in unburnt sites at different distance ranges at different depth to groundwater Distance range (m) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 0-4.9 100 160 0 40 60 200 0 120 Depth to groundwater (m) 5-9.9 10-14.9 15-19.9 200 133.33 166.67 66.67 100 20 20 33.333 0 0 40 20 0 0 >20 0 0 0 0 0 0 0 0 0 0 Appendix 24: The plant density of A longifolia subsp longifolia in burnt sites at different distance ranges at different depth to groundwater Distance range (m) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 0-4.9 1433.33 766.67 933.33 3133.33 1833.33 466.67 1300 933.33 1233.33 3700 Depth to groundwater (m) 5-9.9 10-14.9 15-19.9 0 0 0 0 0 0 0 0 0 0 >20 0 0 0 0 0 0 0 0 0 0 Appendix 25: The plant density of A iteaphylla at different distance ranges at different depth to groundwater Distance range (m) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 0-4.9 60 0 0 0 0 Depth to groundwater (m) 5-9.9 10-14.9 15-19.9 60 20 80 200 20 400 0 20 0 20 0 0 0 0 0 20 0 0 0 >20 20 40 0 0 0 188 Appendix 26: Occurrence number and percentage of Acacia species on different understorey cover Cover Class Very Dense Dense MidDense Sparse Open Total A longifolia Unburnt No of % plants 42 A longifolia - Burnt No of plants % A iteaphylla Unburnt No of % plants 40 386 82 13 13 18 4 17 16 49 10 17 16 105 16 15 100 15 472 100 23 15 46 50 33 100 Appendix 27: t-Test results determining differences in plant density, basal area and biovolume of A longifolia subsp longifolia in burnt and unburnt sites: Two-sample Assuming Variances (α=0.05) Plant Density (mean plants/ha) Unburnt Burnt 53.6 246 67 33.33 633.33 40 693.33 20 10 Basal area (mean m2/ha) Unburnt Burnt 6.407E-05 8.684E-06 3.525E-05 2.765E-05 2.058E-05 3.79E-05 6.81E-06 8.426E-07 Biovolume (mean m3/ha) Unburnt Burnt 0.69 0.08 0.0003 0.17 0.03 0.27 0.0001 0.03 Appendix 28: The number of A longifolia subsp longifolia plants under a tree and the overall tree cover percentage in unburnt sites Unburnt Sites – A longifolia subsp longifolia No of Plants under No of plants not Location Site tree under a tree Thomsons Lake Nature Reserve Thomsons Lake Nature Reserve Anketell Road De Haer Road Piara Total number 62 15 12 99 0 189 Appendix 29: The number of A longifolia subsp longifolia plants under a tree and the overall tree cover percentage in burnt sites Burnt Sites – A longifolia subsp longifolia No of Plants under No of plants not Location Site tree under a tree Shirley Balla Swamp Reserve 59 15 Shirley Balla Swamp Reserve 112 78 Forrestdale 72 136 Total Number 243 229 Appendix 30: The number of A iteaphylla plants under a tree and the overall tree cover percentage in surveyed sites Location Site Canning Vale Road De Haer Road De Haer Road Wandi Nature Reserve Battersby Road Neerabup Neerabup Total number A iteaphylla No of Plants under tree 1 16 34 No of plants not under a tree 1 12 190