IMPACT OF FIRE ON BIODIVERSITY OF THE GNANGARA GROUNDWATER SYSTEM Barbara Wilson, Leonie Valentine, Janine Kuehs, Marnie Swinburn, and Kristen Bleby Department of Environment and Conservation November 2010 Impact of fire on biodiversity of the Gnangara Groundwater System Barbara Wilson, Leonie Valentine, Janine Kuehs, Marnie Swinburn, and Kristen Bleby Report for the Gnangara Sustainability Strategy and the Department of Environment and Conservation Government of Western Australia Department of Environment and Conservation Gnangara Sustainability Strategy Taskforce Department of Water 168 St Georges Terrace Perth Western Australia 6000 Telephone +61 8 6364 7600 Facsimile +61 8 6364 7601 www.gnangara.water.wa.gov.au © Government of Western Australia 2010 November 2010 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968 , all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to the Department of Conservation and Environment. This document has been commissioned/produced as part of the Gnangara Sustainability Strategy (GSS). The GSS is a State Government initiative which aims to provide a framework for a whole of government approach to address land use and water planning issues associated with the Gnangara groundwater system. For more information go to www.gnangara.water.wa.gov.au Acknowledgements The Department of Environment and Conservation – Gnangara Sustainability Strategy would like to thank Dr Gordon Friend and Dr Neil Burrows for reviewing and commenting on the draft document. Photo clockwise from top: Burnt Banksia woodland, Burning Banksia woodland, Flowering Banksia sessilis (photo courtesy of Leonie Valentine), Recovering Banksia woodland, Rankinia adelaidensis (photo courtesy of Kristen Bleby). Gnangara Sustainability Strategy Contents Summary ............................................................................................1 Introduction ........................................................................................3 Gnangara Groundwater System......................................................................................... 5 The Gnangara Sustainability Strategy............................................................................... 6 Fire Projects for the GSS................................................................................................... 9 Impacts of fire on flora.....................................................................13 Post-fire vegetation dynamics and fire regimes .......................................................... 15 Previous studies in the GSS study area ........................................................................... 18 Flora responses to fire on the Geraldton Sandplain..................................................... 18 Flora responses to fire on the Swan Coastal Plain ...................................................... 19 Responses of individual species .............................................................................. 19 Responses in plant populations and communities................................................... 20 Fire responses of threatened ecological communities and declared rare flora............ 22 GSS Flora studies (2007 to 2010) ................................................................................... 24 Post-fire Regeneration Strategies ................................................................................ 24 Juvenile Periods........................................................................................................... 25 Examining juvenile periods across a fire chronosequence.......................................... 25 Impact of fire on plant species richness ...................................................................... 27 Flora Vital Attributes Summary ...................................................................................... 29 Impacts of fire on fauna ...................................................................33 Previous studies in the GSS study area ........................................................................... 40 GSS Projects-fauna studies 2007 to 2010 ....................................................................... 43 Patterns of ground-dwelling vertebrate biodiversity (Valentine et al. 2009b). ........... 43 Reptiles.................................................................................................................... 43 Reptiles and habitat parameters............................................................................... 48 Mammals ................................................................................................................. 49 Impact of fire on avifaunal communities (Davis 2009a)............................................. 53 Impact of fire on food availability for Carnaby’s Cockatoo on the GGS (Valentine 2010)............................................................................................................................ 55 Fauna Attributes Summary: for development of ecological fire regimes ....................... 60 Impact of Fire on Biodiversity i Gnangara Sustainability Strategy Habitat parameters and growth stages............................................................................. 64 Impact of fire on wetlands on GGS .................................................65 Resilience .........................................................................................70 Interaction of fire impacts with other threats on GGS.....................71 Climate change and fire regimes ..................................................................................... 71 Fire and Predators............................................................................................................ 73 Weeds and fire................................................................................................................. 74 Interaction of fire and impact of Phytophthora cinnamomi on flora and fauna.............. 75 Refugia for increasing adaptive capacity and resilience .................77 Western Swamp Tortoise............................................................................................. 77 Southern Brown bandiccot (Isoodon obesulus) Quenda ............................................. 77 Honey Possum............................................................................................................. 78 Development of ecological burning regimes for GGS ....................79 Discussion ........................................................................................80 Impacts on biodiversity ................................................................................................... 80 Development of ecological fire regimes.......................................................................... 86 Factors that increase impacts of inappropriate fire regimes............................................ 89 Recommendations............................................................................91 Reference..........................................................................................93 Appendix 1. Flora Key Fire Response Species .............................110 Impact of Fire on Biodiversity ii Gnangara Sustainability Strategy Impact of Fire on Biodiversity of the Gnangara Groundwater System Summary • Fire has been an integral part of the Australian environment for millions of years • Species and communities are adapted to specific fire regimes, determined by fire intensity, frequency, season and scale. • Inappropriate fire regimes may have undesirable consequences including declines or local extinctions of biota. • Although the impact of inappropriate fire regimes has been identified as a major threat to biodiversity on the Swan Coastal Plain (DEC 2007, 2009 SNCA Plan) information on these impacts is limited. • Vital attributes and juvenile periods of a range of plant species on the GGS have been identified in order to determine appropriate fire intervals. • Key fire response plant species were identified with juvenile periods of 4-6 YSLF (year since last fire) for fire sensitive species relying on seed for reproduction, • The two dominant Banksia species Banksia menziesii and Banksia attenuata (resprouters) have a juvenile period of 8 YSLF. • A minimum fire interval of 8-16 years (twice juvenile period) is recommended based on the information for key flora fire response species • Food availability for the Critically Endangered Carnaby’s Cockatoo was found to vary in relation to time since fire for B. menziesii and B. attenuata where food was highest in 20-30 YSLF years and lowest in < 6 YSLF • It is recommended that burning regimes maximise the amount of Banksia woodland in the 11-30 YSLF to ensure food sources for Carnaby’s cockatoo (particularly in light of the removal of current pine plantation resources between 2002 and 2027) • Strong evidence for post-fire seral responses and habitat requirements of reptile and mammal species was obtained from fauna studies (e.g. Honey possum, Quenda, rakali, Neelaps calonotus , and Menetia greyii ) • Key fire response fauna species were identified based on conservation status and data on the relationships to successional ages and response curves on the GGS Impact of Fire on Biodiversity