The Biodiversity of the Tonle Sap Biosphere Reserve 2005 status review March 2006 Peter J.A. Davidson (compiler) This publication is a technical output of the UNDP/GEF-funded Tonle Sap Conservation Project. Acknowledgements The following provided valuable discussion, unpublished data and/or useful background information: David Ashwell, Eric Baran (World Fish Centre), Kristen Davies (Sam Veasna Centre for Wildlife Conservation, Siem Reap), Paul Dolman (University of East Anglia, U.K.), Tom Evans (WCS), Tom Gray (University of East Anglia, U.K.), Heng Sovannara (WCS), Hong Chamnan (WCS), Rohan Holloway (Australia National University), Dani Jump, Long Kheng (TSBR Secretariat), Ro Borey (WCS), Sin Saenglay (WCS), Sun Visal (WCS), Richard Salter (UNDP TSCP), Joe Walston (WCS). Steve Platt (Oglala Lakota College, South Dakota, U.S.A.) and Bryan Stuart (Field Museum of Natural History, Chicago, U.S.A.) provided references on reptiles and reviewed the her- petology section. Angela Frost (University of Queensland, Australia) provided reference material on rodents. Tom Clements (WCS) provided data and advised on large waterbird monitoring in the Prek Toal Core Area. Zeb Hogan provided a detailed account of the Mekong Giant Catfish. Mr. Cheng Phen (Department of Fisheries) provided useful dis- cussion on the fish sanctuaries. Isabel Beasley and James Cook University provided references and unpublished results on Irrawaddy Dolphin. Nhem Nyta greatly assisted with the reference search, and summarily reviewed many documents in both English and Khmer. Kuoch Kunthea Voreak assisted with the reference search and compiled species lists from various sources. Contents LITERATURE REVIEW..............................................................2 Information Sources.................................................................2 Synopsis of Biodiversity Study in the TSBR.................................2 BACKGROUND.......................................................................4 Physical Geography and Climate................................................4 Drainage and Hydrology...........................................................4 Demography and Land-use........................................................5 Conservation Status of the Tonle Sap Floodplain.........................5 BIODIVERSITY........................................................................7 FUNGI & FLORA....................................................................10 MACROPHYTE FLORA...........................................................11 FAUNA................................................................................18 Mammals.............................................................................18 Birds....................................................................................22 Reptiles...............................................................................29 Amphibians...........................................................................34 Fish.....................................................................................34 INVERTEBRATES...................................................................42 KEY THREATS TO BIODIVERSITY IN THE TSBR.........................44 INTRODUCED SPECIES...........................................................47 BIODIVERSITY IN THE TONLE SAP BIOSPHERE RESERVE: WHAT WE KNOW, AND WHAT WE NEED TO KNOW................49 REPTILES AND AMPHIBIANS..................................................51 REFERENCES........................................................................53 ANNEX 1: PLANT SPECIES RECORDED IN THE TSBR......................63 ANNEX 2: FISH SPECIES RECORDED IN THE TSBR.........................68 ANNEX 3: BIRD SPECIES RECORDED IN THE TSBR.........................72 ANNEX 4: MAMMAL SPECIES RECORDED IN THE TSBR.................76 List of Tables ECOLOGICAL PROCESSES/EVENTS BY HABITAT TYPE.....................8 List of Figures FIG. 1 CROSS SECTION OF FLOOD PLAIN HABITATS.....................11 FIG. 2 DOMINANT PLANT SPECIES IN THE TONLE SAP FLOODPLAIN...............................................................................16 List of Maps TONLE SAP LAKE..........................................................................1 1 INFORMATION SOURCES SYNOPSIS OF BIODIVERSITY TUDY IN THE This study is in essence a literature review. All S TSBR traceable documents relating to biodiversity in the Tonle Sap floodplain have been viewed by The exceptional biodiversity of the Tonle Sap the editor, including published journal papers was first documented as early as the 13th (relatively few), occasional book chapters, the Century by Zhou Daguan, a Chinese visitor to bi-annual journal Cambodia Bird News, pub- Cambodia, who noted the abundance of fish, lished reports (numerous, notably from the frogs, tortoises, turtles, lizards, large croco- Wildlife Conservation Society and the Mekong diles and molluscs on and around the lake River Commission/WUP-FIN, also the United (Zhou 2002). The bas-reliefs of the Angkorian Nations Food and Agriculture Organisation – Bayon Temple depict several key elements of FAO), identification and species reference the Great Lake’s fauna, in particular fish, croc- guides, unpublished reports (very numerous, odiles, turtles and large waterbirds (Roberts including many “trip reports” from field sur- 2002, Bailleux 2003). veys, often in Khmer) and even posters. In cases where references could not be viewed French explorers reported on the rich fisheries directly this is indicated in the text by the of the Tonle Sap (e.g. Garnier 1996), and by phrase “cited in” (e.g. Anon. 2003 cited in the early 20th Century the exceptional produc- Anon. 2005). tivity of Tonle Sap fisheries for export was well known (Petillot 1911, Chevey 1935 cited Reference material was gathered from the in Hortle et al. 2004). Fish studies conducted libraries of the following organisations and during the French colonial period, synthesised institutions: Tonle Sap Biosphere Reserve in Chevey and Le Poulain (1940) and Blache Secretariat (Ministry of Environment - MoE), and Goosen (1954) are still the most compre- Department of Fisheries and the Forest hensive reviews of fish status, distribution and Administration (Ministry of Agriculture, Forests diversity conducted on the Tonle Sap (E. and Fisheries – MAFF), Wildlife Conservation Baran, World Fish Centre, verbally September Society (WCS), World Wide Fund for Nature 2005). French naturalists resident in Cambodia (WWF), Conservation International (CI), Flora during the first half of the 20th Century pub- and Fauna International (FFI), Cambodia lished the first significant information from the Development Resource Institute (CDRI), Tonle Sap region, on birds (Delacour 1929, Cambodia National Mekong Committee Delacour and Jabouille 1928, 1931, Engelbach (CNMC), Mekong River Commission (MRC, 1940). now based in Vientiane, Lao PDR) including the Water Utilisation Programme – Finnish During the post-colonial era (ca.1953-1970), Environment Institute (WUP-FIN), United the French synthesised information on the Nations Development Programme (UNDP), the flora of selected parts of Cambodia, including World Fish Centre, the Royal University of the Tonle Sap (e.g. Dy Phon 1970, 1982, Agriculture (RUA) and the Royal University of Legris and Blasco 1972, Rollet 1972). Bill Phnom Penh (RUPP). Thomas made further ornithological observa- tions and collated these with the earlier stud- Additional material was gathered through per- ies of birds (Thomas and Poole 2003), and sonal correspondence and discussion between Bardach (1959) conducted a study of the fish- the editor and many people working on differ- eries. No significant biodiversity work was ent aspects of biodiversity in the TSBR (see conducted between 1970 and the early Acknowledgements). 1990s. Immediately after the civil war period, the Tonle Sap formed a central focus for biological exploration. This began with short aerial and 2 boat-based surveys for birds (Archibald 1992, birds in parts of the outer floodplain in Banteay Scott 1992, Carr 1994), followed by more Meanchey, Siem Reap and Kompong Thom comprehensive aerial, ground and interview provinces during 2001-2002, as part of the surveys during the dry seasons of 1994 Important Bird Area identification process (Mundkur et al. 1995) and 1996 (Parr et al. (Seng et al. 2003, BirdLife International 1996). This work established that breeding 2004a). Similarly, widespread interview and colonies of several globally threatened large follow-up field surveys were conducted for waterbirds persisted in the forested habitats crocodiles in 2001-2002 (Platt et al. 2004). along the north-western shores of the Tonle First attempts to quantify the watersnake were Sap, south-west of the floating village of Prek conducted in 2000 (Stuart et al. 2000), and Toal, but that they were being heavily exploit- have since been followed up with more ed for their eggs and chicks. Surveys investi- detailed investigations (Brookes et al. 2005). gating the socio-economic drivers behind the waterbird harvest, conducted in 1997, includ- Fish catches from the Tonle Sap have been ed conservation awareness work, which led to reported on annually and in some detail since a substantial reduction in collection that year the mid-1990s (e.g. van Zalinge and Touch (Ear-Dupuy et al. 1998). 1996, Nao 1997, van Zalinge et al. 1999, Lieng and van Zalinge 2001), but very few In February-March 1997, a detailed study of studies of fish diversity and distribution have