University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2004 The effect of fire and grazing on the Cumberland Plain Woodlands Samantha Clarke University of Wollongong Recommended Citation Clarke, Samantha, The effect of fire and grazing on the Cumberland Plain Woodlands, Master of Science - Research thesis, School of Biological Sciences, University of Wollongong, 2004. http://ro.uow.edu.au/theses/2700 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] The Effect of Fire and Grazing on the Cumberland Plain Woodlands A thesis submitted in partial fulfillment of the requirements for the award of the degree Master of Science (Research) from THE UNIVERSITY OF WOLLONGONG By SAMANTHA CLARKE Bachelor of Science (Biology) DEPARTMENT OF BIOLOGICAL SCIENCES 2004 CERTIFICATION I, Samantha Clarke, declare that this thesis, submitted in partial fulfillment of the requirements for the award of Master of Science (Research), in the Department of Biological Sciences, University of Wollongong, is wholly my own work unless otherwise referenced or acknowledged. The document has not been submitted for qualifications at any other academic institution. Samantha Clarke 20 June 2004 ABSTRACT Temperate grassy woodlands throughout the world have suffered the effects of changed disturbance regimes, in particular, fire and grazing, due to human activities. Since European settlement fire and tree clearing has been used to modify grassy woodland vegetation for livestock grazing and agriculture. As a consequence some species, particularly shrubs and trees, have been reduced or eliminated and both native and introduced grasses have become more dominant. It is important to understand how disturbance regimes are affecting grassy woodlands to ensure long-term survival and diversity of the community. The Cumberland Plain Woodlands are a good example of the magnitude of destruction endured by a typical grassy w~odland community. They are found in small remnants within the western Sydney region and are severely fragmented and disturbed with approximately only 6 % remaining. The Cumberland Plain Woodlands are listed as an endangered ecological community under the Threatened Species ConseNation Act, 1995 and the Environment Protection and Biodiversity ConseNation Act, 1999. This listing is a consequence of widespread destruction and fragmentation of the community due to tree clearing, agriculture and urbanisation. Little is known of the effect of changed disturbance regimes on the Cumberland Plain Woodland remnants and other vulnerable communities growing upon shale in western Sydney with most research focussing on the vegetation communities growing upon Hawkesbury Sandstone, which initiated this research. The study area was located within one of the largest remnants of Cumberland Plain Woodlands, which is found at Holsworthy Military Area, western Sydney. Holsworthy has been part of the army training area for the last 100 years and therefore is isolated from growing urbanisation, agriculture and livestock grazing. The impact of frequent fire is of concern in this area as past management practices were to burn the area regularly to remove vegetation and create an open understorey able to be used for army training activities. Also, small firearms training activities often ignite fires in the woodland due to bullets missing targets and igniting the vegetation. Fires in the area are generally left to burn out without any intervention due to the danger of explosion of unexploded ordnances throughout the training area. High fire frequency and the cessation of livestock grazing at Holsworthy highlighted the necessity to answer the following questions: (i) How do plant species in the Cumberland Plain Woodlands respond to different fire regimes? ('ii) How do these plant species respond to grazing by animals other than domestic livestock, such as macropods and rabbits? And (iii) what effect does the heat and smoke from fire have on grass germination? An exclosure experiment using various fire and grazing treatments was used to answer these questions and determine if the richness and abundance of species changed over a five-year period. Also, a laboratory germination experiment was used to determine how 22 grass species from the Cumberland Plain Woodlands respond to heat and smoke treatments designed to simulate the process of fire. This study found that (i) past fires affected plant community composition in the Cumberland Plain Woodlands at Holsworthy Military Area, generally reducing the abundance of shrubs relative to grasses, although some particular shrub species were not reduced in abundance, (ii) community composition did not appear to be strongly affected by grazing, and (iii) germination of some grass species was stimulated by heat and/or smoke but germination of others was reduced. This research indicates that fire is an important and frequent disturbance in the Cumberland Plain Woodlands at Holsworthy Military Area. Understanding the current fire regime is necessary to determine appropriate management strategies to ensure the survival of the Cumberland Plain Woodlands and other grassy woodland communities. This project enhances the research and monitoring component of the Plan of Management for the recovery of the Cumberland Plain Woodlands, Holsworthy Military Area. It highlights the need for landscape heterogeneity to maintain survival and diversity of the ii community and increases the knowledge of the effect of heat and smoke from fire on the germination of grasses in grassy woodlands. iii Acknowledgments I would like to thank many people for their help and guidance during the course of this project, I cannot name them all here but their support and encouragement has been gratefully appreciated. I would like to make a special thank you to some of them: I would like to thank Marina Peterson from the Department of Defence for her willingness to support the ongoing process of this research, financial support and advice on army procedures. A big thank you to Kris French, my supervisor, for her encouragement to pursue my ambitions and for providing the opportunity to undertake this project. Kris's advice, support and friend~hip have been fantastic. Warrant Officer Mick Blacksland, Holsworthy Range Control and security staff of Total Asset Management Services for help in accessing my study sites. Sarah Hill for help in the initial location of the experimental sites and for sharing valuable information of the study area. Sarah's help has been invaluable and much appreciated. Jean Clarke, Sarah Hill, Maria Adams, Marie Turner and Kris French who were all excellent field assistants. Lotte von Richter, Cathy Offord and staff of the Royal Botanic Gardens, Mt Annan for advice on procedures of the germination experiment and help with species selection and location and for use of the research laboratory. Thanks to Lotte for technical assistance in the field and laboratory. Belinda Pellow has provided help with plant identification, map production and much more. I am very grateful to Belinda for help and advice on so many issues. iv The Janet Cosh Herbarium girls, Belinda Pellow and Jean Clarke, thanks to you both for being so supportive and for your friendship. Thanks to Jack Baker for his encouragement, advice and comments on earlier drafts of this thesis. David Keith for advice on experimental design and analysis and for comments on earlier drafts of the germination chapter. Jane Wasley for assistance with the construction of the smoke machine. Ken Russell for help and advice on statistical analysis. Jocelyn Howell and Doug Benson for advice on the grasses of the Cumberland Plain Woodlands. Lastly, to my family Ginge, Laura and Stacey. Thanks to Ginge for his constant encouragement, patience and tolerance. Thanks to Laura and Stacey, for their patience and acceptance. Without the love and support of my family this project would have been impossible and I am forever grateful. v Table of Contents ABSTRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDIXES Chapter 1 - Introduction 1 1.1 Background 1 1.2 Disturbance in grassy woodlands 1 1.3 Distribution of grassy woodlands 2 1.4 The effect of fire on grassy woodlands_ 4 1.4.1 Fire frequency 4 1.4.2 Fire intensity 5 1.4.3 Season of fire 5 1.5 The effect of grazing on grassy woodlands 6 1.5.1 Domestic livestock 7 1.5.2 Rabbits 7 1.5.3 Native Herbivores 8 1.6 Fire and grazing interactions 8 1. 7 Management of grassy woodlands in Australia 10 1.8 Cumberland Plain Woodlands 11 1.8.1 Fire and grazing at Holsworthy 12 1.9 Aims of the study 12 Chapter 2 - The effect of fire and grazing on plant species richness and abundance 14 2.1 Introduction 14 2.2 Methods 17 2.2.1 Location 17 2.2.2 Experimental design 17 vi 2.2.3 Surveys 18 2.2.4 Total and mean species richness 19 2.2.5 Rainfall 19 2.2.6 Statistical analysis 19 2.3 Results - Part A - Changes in Species Richness 1997-2002 23 2.3.1 Overview of the yearly changes in total species richness 23 2.3.2 Rainfall 26 2.3.3 Differences among fence and fire treatments 28 2.3.4 Multivariate analysis of presence/absence data 29 2.3.4.1 Total species 29 2.3.4.2 Shrubs 31 2.3.4.3 Herbs and Poaceae 32 2.3.5 Grazing and fire interactions 36 2.4 Results - Part B - Changes in Cover_Abundance 2001-2002 37 2.4.1 Multivariate analysis of cover abundance data 37 2.4.1.1 Total species