Format: ORAL

Daniel C. Thomas1, Wisnu H. Ardi2, Yu H. Chong3, Philip Thomas4 Mark Hughes4

1 National Parks Board, Singapore Botanic Gardens, Singapore 2 University of Florida, Institute of Food and Agricultural Sciences, USA 3 Nanyang Technological University, School of Biological Sciences, Singapore 4 Royal Botanic Garden Edinburgh, Scotland, UK

The feasibility of conservation and extinction risk assessments of plant species using the criteria outlined by The International Union for the Conservation of Nature (IUCN) Red List can be severely compromised by the limited availability of crucial underlying data. This is particularly true for species-rich, tropical plant taxa with a preponderance of microendemics, whose species are often represented by only a few collections in herbaria worldwide. Begonia, a megadiverse, pantropical genus ( 2100 species) and characteristic element in the herb layer of tropical forests, is a prominent example. The Begonia flora of the Indonesian island of Sulawesi, for example, is comprised of 65 species, 62 of which are endemic to the island, and 51 of which are represented by less than 10 collections in herbaria worldwide. Here we discuss how, despite of these data limitations, meaningful conservation assessments can be achieved by integrating (i) extensive fieldwork and field observations; (ii) herbarium collection locality data; (iii) data primarily based on remote sensing approaches including forest landscape integrity, forest cover loss and land cover categories; (iv) locality number estimates by evaluating the impact range of plausible threats (e.g. concession sizes for palm oil plantations and logging, or the size of large-scale forest fires), and (v) area of habitat estimations using overlap analyses of elevational ranges, forest landscape integrity and limestone karst distributions. The results indicate that most Sulawesi Begonia species are narrow endemics whose rainforest and limestone karst habitats have substantially deteriorated in the last two decades: 28 species are assessed as Critically Endangered, 24 as Endangered, six as Vulnerable, five as Least Concern and two species were considered Data Deficient. Conservation assessments of species-rich taxa such as Begonia, which include numerous narrow endemics, are important for the formulation of effective national-level action to prevent further extinction.