Gunbower Forest Ramsar Site Ecological Character Description June 2011 Citation: Hale, J. and Butcher, R., 2011, Ecological Character Description for the Gunbower Forest Ramsar Site. Report to the Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), Canberra. Acknowledgements: Peter Cottingham, Peter Cottingham and Associates (workshop facilitation). Halina Kobryn, Murdoch University (mapping and GIS). Jane Roberts (expert knowledge floodplain vegetation). DSE (2010) formed the basis of many sections of this updated Ecological Character Description. DSE (2010) was prepared for the Department of Sustainability and Environment (DSE) by Ecological Associates Pty Ltd, Malvern South Australia with the assistance of a project steering committee, which included representatives from DSE (Victorian Government), DSEWPaC (Australian Government), the Mallee Catchment Management Authority and Parks Victoria. The steering committee was comprised of the following: • Leah Beesley, DSE • Tamara Boyd, Parks Victoria • Lyndell Davis, DSEWPaC • John Foster, DSEWPaC • Janet Holmes, DSE • Richard Loyn, DSE • Shar Ramamurthy, DSE • Melanie Tranter, North Central Catchment Management Authority • Keith Ward, Goulburn-Broken Catchment Management Authority • Kane Weeks, Parks Victoria Introductory Notes: This Ecological Character Description (ECD Publication) has been prepared in accordance with the National Framework and Guidance for Describing the Ecological Character of Australia’s Ramsar Wetlands (DEWHA 2008). The Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) prohibits actions that are likely to have a significant impact on the ecological character of a Ramsar wetland unless the Commonwealth Environment Minister has approved the taking of the action, or some other provision in the EPBC Act allows the action to be taken. The information in this ECD Publication does not indicate any commitment to a particular course of action, policy position or decision. Further, it does not provide assessment of any particular action within the meaning of the EPBC Act (Cth), nor replace the role of the Minister or his delegate in making an informed decision to approve an action. The Water Act 2007 requires that in preparing the Murray-Darling Basin Plan, the Murray- Darling Basin Authority (MDBA) must take into account ECDs of declared Ramsar wetlands prepared in accordance with the National Framework. This ECD Publication is provided without prejudice to any final decision by the Administrative Authority for the Ramsar Convention in Australia on change in ecological character in accordance with the requirements of Article 3.2 of the Ramsar Convention. Disclaimer: While reasonable efforts have been made to ensure the contents of this ECD are correct, the Commonwealth of Australia as represented by the Department of Sustainability, Environment, Water, Population and Communities does not guarantee and accepts no legal liability whatsoever arising from or connected to the currency, accuracy, completeness, reliability or suitability of the information in this ECD. Note: There may be differences in the type of information contained in this ECD publication, to those of other Ramsar wetlands. Cover photos: Gunbower Forest – Jeanette Muirhead (DSEWPaC); aerial photo of Gunbower Forest – Jim Mollison (DSEWPaC). ii Table of Contents Glossary ......................................................................................................................................v List of Abbreviations ................................................................................................................ viii Executive Summary ................................................................................................................... ix 1. Introduction ............................................................................................................................ 1 1.1 Site details ........................................................................................................................ 1 1.2 Statement of purpose ....................................................................................................... 2 1.3 Relevant treaties, legislation and regulations .................................................................. 4 1.4 Method ............................................................................................................................. 8 2. General Description of Gunbower Forest Ramsar Site ......................................................... 9 2.1 Location ............................................................................................................................ 9 2.2 Land tenure ...................................................................................................................... 9 2.3 Wetland types ................................................................................................................ 10 2.4 Ramsar criteria ............................................................................................................... 13 2.4.1 Criteria under which the site was designated.......................................................... 13 2.4.2 Assessment based on current Ramsar criteria ....................................................... 15 3. Critical Components and Processes ................................................................................... 20 3.1 Identifying critical components and processes .............................................................. 20 3.2 Supporting components and processes ........................................................................ 22 3.2.1 Climate .................................................................................................................... 22 3.2.2 Geomorphic setting ................................................................................................. 24 3.2.3 Water quality ........................................................................................................... 25 3.2.4 Aquatic mammals, reptiles and frogs ...................................................................... 28 3.3 Critical components and processes ............................................................................... 28 3.3.1 Hydrology ................................................................................................................ 29 3.3.2 Wetland vegetation .................................................................................................. 34 3.3.3 Fish .......................................................................................................................... 41 3.3.4 Wetland birds .......................................................................................................... 43 4. Ecosystem Services ............................................................................................................ 46 4.1 Overview of benefits and services ................................................................................. 46 4.2 Identifying critical ecosystem services and benefits ...................................................... 46 4.3 Critical services .............................................................................................................. 48 4.3.1 Supports a diversity of wetland types ...................................................................... 48 4.3.2 Provides physical habitat for wetland bird breeding and feeding ............................ 51 4.3.3 Supports threatened species .................................................................................. 55 4.3.4 Maintains ecological connectivity for spawning / recruitment of native fish ............ 56 4.3.5 Organic carbon cycling ............................................................................................ 58 4.4 Conceptual models ........................................................................................................ 59 4.1 Wet phase (filling and inundated state) ...................................................................... 59 4.2 Dry phase (drying and dry state) ................................................................................ 61 iii 5. Limits of Acceptable Change ............................................................................................... 62 5.1 Process for setting Limits of Acceptable Change (LACs) .............................................. 62 5.2 LACs for the Gunbower Forest Ramsar site .................................................................. 63 6. Threats to Ecological Character .......................................................................................... 70 6.1 Water resource use ........................................................................................................ 72 6.2 Climate change .............................................................................................................. 73 6.3 Forestry activities ........................................................................................................... 73 6.4 Altered fire regimes ........................................................................................................ 74 6.5 Invasive species ............................................................................................................. 74 6.6 Human disturbance .......................................................................................................