Additional Land South of the Gas Treatment Plant Vegetation and Flora Survey October 2013 Prepared for Chevron Australia Pty Ltd Astron Environmental Services 129 Royal Street East Perth WA 6004 Phone: (08) 9421 9600 Fax: (08) 9421 9699 Report Reference: 2609-13-BSR-1Rev0_131128 Email: [email protected] Doc. ID: G1-NT-REP00000220 Doc. ID: G1-NT-REP00000220 Additional Land South of the Gas Treatment Plant Vegetation and Flora Survey Prepared for Chevron Australia Pty Ltd Job Number: 2609-13 Reference: 2609-13-BSR-1Rev0_131128 Revision Status Rev Date Description Author(s) Reviewer A 01/11/2013 Draft Issued for Client Review N. Cadd J. Kruger B 08/11/2013 Revised Draft Issued for Client Review N. Cadd J. Kruger C 12/11/2013 Revised Draft Issued for Client Review N. Cadd V. Clarke 0 28/11/2013 Final Issued for Information N. Cadd V. Clarke Approval Rev Date Issued to Authorised by Name Signature A 01/11/2013 A. Smith/S. Finn S. Pearse B 08/11/2013 A. Smith/S. Finn S. Pearse C 12/11/2013 A. Smith/S. Finn S. Atkinson 0 28/11/2013 A. Smith/S. Finn S. Pearse © Copyright 2012 Astron Environmental Services Pty Ltd. All rights reserved. This document and information contained in it has been prepared by Astron Environmental Services under the terms and conditions of its Doc.contract ID: with G1-NT-REP00000220 its client. The report is for the clients use only and may not be used, exploited, copied, duplicated or reproduced in any form or medium whatsoever without the prior written permission of Astron Environmental Services or its client. Chevron Australia Pty Ltd Additional Land South of the Gas Treatment Plant – Vegetation and Flora Survey, October 2013 Abbreviations Abbreviation Definition Astron Astron Environmental Services BoM Bureau of Meteorology Chevron Chevron Australia Pty Ltd DPaW Department of Parks and Wildlife DRF Declared Rare Flora EIS Environmental Impact Statement EPA Environmental Protection Authority GTPS Gas Treatment Plant Site ha Hectare km Kilometre Mattiske Mattiske Consulting Pty Ltd mm Millimetre P Priority PEC Priority Ecological Community TEC Threatened Ecological Community Page | ii Doc. ID: G1-NT-REP00000220 Chevron Australia Pty Ltd Additional Land South of the Gas Treatment Plant – Vegetation and Flora Survey, October 2013 Executive Summary To facilitate operations and site management associated with the Gorgon Gas Development, Chevron Australia Pty Ltd has requested the use of an additional 32 hectare of uncleared land on Barrow Island. The additional area is located directly south of the Gorgon Development Gas Treatment Plant. Astron Environmental Services was commissioned by Chevron Australia Pty Ltd to undertake a vegetation and flora survey of the 36 hectare study area, within which the proposed 32 hectare site will be identified for use by Chevron. Survey of the area was undertaken between 14 and 16 October 2013 using methods consistent with relevant Environmental Protection Authority guidance for terrestrial vegetation and flora surveys. Vegetation in the study area is primarily characterised by Melaleuca cardiophylla over Triodia wiseana and Triodia angusta hummock grassland. Where Melaleuca cardiophylla is not dominant, it is replaced with Acacia bivenosa. This vegetation is considered typical of vegetation on comparable landforms across Barrow Island, and has been previously recorded outside of the study area (Astron 2008a; 2008b; 2008c; 2008d; 2009; 2010a; 2010b; 2001a; 2011b). Vegetation was in ‘excellent‘ (Trudgen 1988) condition with no visible signs of disturbance recorded. A total of 37 vascular flora species representing 30 genera and 22 families were recorded from the study area. The families most represented in the survey area were Fabaceae (legumes), Malvaceae (mallows), Asteraceae (daisies), Poaceae (grasses) and Solanaceae (potato family). One priority flora species, Corchorus congener (Priority 3), was recorded within the study area. While the recorded occurrence of Corchorus congener within the survey area was low, this species is relatively abundant and widespread across Barrow Island (Astron 2011c). Two significant flora species were also recorded within the study area; Melaleuca cardiophylla and Hakea lorea subsp. lorea. These species are not protected by legislation however are considered ‘significant’ on Barrow Island as they are considered to have low regenerative capacity when subject to disturbance (Astron 2011c). Melaleuca cardiophylla was one of the dominant flora species recorded within the study area and it is widely known from flats and limestone habitats across Barrow Island (Astron 2008c; 2010a; 2011a). Three individuals of Hakea lorea subsp. lorea were recorded within the study area. This species is not abundant on Barrow Island but appears to be more widespread than originally recorded in the Mattiske (1993) survey, being found in a number of habitats (Astron 2009b; 2011c). No introduced flora was identified within the study area. Page | iii Doc. ID: G1-NT-REP00000220 Chevron Australia Pty Ltd Additional Land South of the Gas Treatment Plant – Vegetation and Flora Survey, October 2013 Table of Contents 1 Introduction ..................................................................................................................................... 1 1.1 Project Background ................................................................................................................. 1 1.2 Scope and Objectives .............................................................................................................. 1 2 Methodology ................................................................................................................................... 3 2.1 Desktop Assessment ............................................................................................................... 3 2.2 Field Survey ............................................................................................................................. 3 2.2.1 Data Collection ............................................................................................................ 4 2.2.2 Taxonomy and Nomenclature .................................................................................... 4 3 Limitations ....................................................................................................................................... 4 4 Results ............................................................................................................................................. 5 4.1 Desktop Study ......................................................................................................................... 5 4.1.1 Database Search Results ............................................................................................. 5 4.1.2 Seasonal Conditions .................................................................................................... 5 4.2 Vegetation and Flora Field Assessment .................................................................................. 6 5 Discussion ........................................................................................................................................ 9 6 References ..................................................................................................................................... 10 List of Figures Figure 1: Study area location. ................................................................................................................. 2 Figure 2: Long-term mean monthly rainfall (1999 – 2013) (mm) and actual monthly rainfall (mm) received at the Barrow Island Airport weather station in the 12 months preceding the field survey (BoM 2013). ............................................................................................................................................ 6 List of Plates Plate 1: Corchorus congener. .................................................................................................................. 8 List of Tables Table 1: Database searches requested. .................................................................................................. 3 Table 2: Mapped vegetation associations within the study area. .......................................................... 7 Table 3: Plant families and genera most frequently recorded in the study area. .................................. 7 Table 4: Conservation significant flora species locations within the study area. ................................... 8 Page | iv Doc. ID: G1-NT-REP00000220 Chevron Australia Pty Ltd Additional Land South of the Gas Treatment Plant – Vegetation and Flora Survey, October 2013 List of Appendices Appendix A: Database Search Results Appendix B: Vegetation Classification and Condition Scales Appendix C: Quadrat and Relevé Data Reports Appendix D: Vascular Flora Species List Page | v Doc. ID: G1-NT-REP00000220 Chevron Australia Pty Ltd Additional Land South of the Gas Treatment Plant – Vegetation and Flora Survey, October 2013 1 Introduction 1.1 Project Background Barrow Island is located approximately 55 kilometres (km) off the Pilbara coastline of Western Australia. The island is approximately 25 km in length and 10 km wide, covering an area of 23,567 hectares (ha). Barrow Island was declared a Class A Nature Reserve in 1910, reflecting its high conservation values (Chevron Australia Pty Ltd (Chevron) 2005). For more than 40 years, Barrow Island has supported a production oil field. Chevron is currently expanding its