Biodiversity Values and Threatening Processes of the Gnangara Groundwater System Edited by Barbara A. Wilson and Leonie E. Valentine Department of Environment and Conservation September 2009 Biodiversity values and threatening processes of the Gnangara groundwater system Edited by Barbara A. Wilson and Leonie E. Valentine Report for the Gnangara Sustainability Strategy and the 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 2009 2009 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 the Scientific Advisory Committee members for their guidance and comments on draft manuscripts of this report: Dr Ian Abbott, Dr Stephen Van Leeuwin, Dr Gordon Friend, Dr Pierre Horwitz, Dr Mike Bamford and Dr Don McFarlane. The Department of Environment and Conservation – Gnangara Sustainability Strategy would also like to thank the experts consulted during the writing of this report: Dr Pierre Horwitz, Katherine Zdunic, Graeme Behn, Dr Robert Davis, Dr Val English, Dr Chris Dunne, Dr Joanne Isaac and Karen Bettink. Many thanks to the Swan Coastal District staff for their assistance over the last two years, special thanks to Clayton Sanders, Mike Meinema Melissa Hoskins and Leigh Sage. The Department of Environment and Conservation – Gnangara Sustainability Strategy team includes the Project Managers: Paul Brown and Dr Barbara Wilson; and team members: Dr Mark Garkaklis, Dr Leonie Valentine, Dr Kristen Bleby, Janine Kinloch, Alice Reaveley, Marnie Swinburn, Tracy Sonneman, Natalia Huang, Brent Johnson, David Mickle, Katie Montgomery, Janine Kuehs and Lara Ryniker. Cover page photos (clockwise from top left corner): Morethia obscura, prescribed burn in Banksia woodland, Tarsipes rostratus (honey possum), Banksia woodland, Neelaps calonotos (black-striped snake), Phytophthora cinnamomi infected Banksia spp., Heleioporus eyrie (moaning frog), Lake Goolellal, juvenile Isoodon obesulus fusciventor (quenda), Waitzia suaveolens, Calyptorhynchus latirostris (Carnaby’s black- cockatoo), Banksia menziesii flower. Centre photo: aerial view of Yeal Nature Reserve following fire. Photo credit for all photos: L. Valentine, except prescribed burn in Banksia woodland (photo credit: L. Sage) and aerial view of Yeal Nature Reserve following fire (photo credit: DEC-GSS). Gnangara Sustainability Strategy – Biodiversity Report Table of Contents Chapter One: Introduction and Approach Barbara Wilson Key Points Introduction The Gnangara Sustainability Strategy Aims of this report The study area – Gnangara groundwater system Climate change Groundwater declines on the Gnangara groundwater system Modelling future impacts Biodiversity, threats and resilience Approach adopted for the GSS biodiversity project Fauna and flora surveys Alignment of GSS and DEC Nature Conservation Division projects and planning Data protocols and standards Structure of the biodiversity report References Chapter Two: Floristic Biodiversity and Vegetation Condition Leonie Valentine, Kristen Bleby, Marnie Swinburn, Janine Kinloch and Barbara Wilson Key Points Introduction Species richness and endemicity The floristic diversity of south-west Western Australia Floristic diversity of the GSS study area Threatened and priority listed flora Threatened ecological community Protection of threatened ecological communities within the GSS study area Overview of vegetation classifications Vegetation complexes Floristic community types Site-vegetation types Table of Contents i Gnangara Sustainability Strategy – Biodiversity Report Bush Forever – Perth’s Bushplan Project Assessing biodiversity values of remnant vegetation Summary of DEC-GSS projects (2007-09) Project 1. Patterns of floristic diversity in the GSS study area Project 2. Monitoring vegetation condition in Banksia woodlands in the GSS study area: the role of remote sensing tools Project 3. Remnant vegetation in the pine plantations and Lake Pinjar Discussion Recommendations References Chapter Three: Fauna Biodiversity Kristen Bleby, Leonie Valentine, Alice Reaveley, Barbara Wilson, Natalia Huang Key Points Introduction Species richness and endemicity and threatened taxa The fauna diversity of south-west Western Australia Faunal diversity in the GSS study area Threats to terrestrial fauna in the GSS study area Declining groundwater levels Summary of DEC-GSS projects (2007-09) Project 1. Patterns of ground-dwelling vertebrate biodiversity in the GSS study area Project 2. Targets trapping of quenda and rakali in the GSS study area Project 3. Assessing the occurrence and status of frogs in the GSS study area Discussion Recommendations References Chapter Four: Wetlands and Groundwater-Dependent Ecosystems Pierre Horwitz, Bea Sommer, Ray Froend Key Points Introduction Wetland definitions and values Table of Contents ii Gnangara Sustainability Strategy – Biodiversity Report Water cycle and groundwater interface Hydrological cycles of permanently or seasonally inundated wetlands of the Gnangara groundwater system Wetland geomorphology and wetland sediments Wetland sediments of the Gnangara groundwater system Biodiversity: flora and fauna Common wetland vegetation types of the Swan Coastal Plain Non-vascular plants Aquatic invertebrates Wetland vertebrate fauna Wetland communities Protection of ecological values Discussion Recommendations References Chapter Five: Wetlands – Changes, Losses and Gains Pierre Horwitz, Bea Sommer, Pauline Hewitt Key Points Introduction Paleohistory, paleoclimate and wetlands A recent history of wetlands: colonisation north of the Swan River Processes involved in degradation and loss of wetlands and groundwater-dependent ecosystems Altered hydrological regimes Land use change – clearing, filling and fragmentation of wetland habitats Nutrient enrichment Acidification Fire impacts Threatened wetland and groundwater dependent ecological communities Hydrology – biology – society linkages Wetland monitoring Discussion Recommendations References Table of Contents iii Gnangara Sustainability Strategy – Biodiversity Report Chapter Six: Habitat Loss and Fragmentation Barbara Wilson, Leonie Valentine, Janine Kinloch, Tracy Sonneman and Marnie Swinburn Key Points Introduction Habitat loss and fragmentation Impacts on ecological processes Impacts on plant populations Impacts on vertebrate fauna Habitat loss and ecological thresholds Pine plantations and habitat fragmentation Conservation management in fragmented landscapes Ecological linkages on the Swan Coastal Plain and the Gnangara groundwater system Summary of DEC-GSS projects (2007-09) Project 1. Status of remnant vegetation Project 2. Ecological linkages Project 3. Connectivity and corridor analysis Discussion Recommendations References Chapter Seven: Fire Regimes Kristen Bleby, Alice Reaveley, Leonie Valentine and Barbara Wilson Key Points Introduction Gnangara sustainability strategy and fire Fire regimes Responses of flora to fire Responses of fauna to fire Fire impacts on the biodiversity in the GSS study area of the Swan Coastal Plain Fire management for biodiversity conservation Fire regimes based on vital attributes Fire regimes to create diverse habitats and mosaics Fire regimes to manage fuel accumulation DEC Swan Region fire management Prescribed burning Table of Contents iv Gnangara Sustainability Strategy – Biodiversity Report Prescribed burning in the GSS study area Wildfire in the GSS study area Summary of DEC-GSS projects (2007-09) Project 1. Effects of time since fire on ground-dwelling vertebrates Project 2. Fire and the Banksia woodlands of the Swan Coastal Plain – fuel reduction burns and water recharge on the Gnangara Mound Appropriate fire regimes in the GSS study area Future work on appropriate fire regimes Discussion Recommendations References Chapter Eight: Impacts of Introduced Species on Biodiversity Alice Reaveley, Karen Bettink and Leonie Valentine Key Points Introduction Pest plants Characteristics of pest plants Impacts of pest plants on biodiversity Introduced pest plants in the GSS study area DEC management of introduced plant species Weed management in the GSS study area Introduced fauna Impacts of introduced fauna on biodiversity Management of introduced fauna DEC management of introduced fauna Responses of wildlife to management of introduced species Summary of DEC-GSS projects (2007-09) Project 1. Feral sandpad survey Project 2. Targeted quenda survey Discussion Recommendations References Table of Contents v Gnangara Sustainability Strategy – Biodiversity Report Chapter Nine: Distribution