This proposal requests supplemental funds to permit Drs. Peter S. Ashton and James V. LaFrankie, Arnold Arboretum, Harvard University, to complete with Mr. Hua-Seng Lee, Department of Forestry, Sarawak, Malaysia, the training of U.S. and Malaysian personnel essential to the success of their NSF-supported research on tropical biodiversity. The research itself deals with understanding how tree biodiversity is maintained in balance in the Lambir National Park, Sarawak, East Malaysia, in the Northwest Borneo hotspot, an area that may be the most species rich forest in the Old World. A special 50 hectare plot has been reserved in which the role of soil heterogeneity in maintaining species diversity can be studied. A possible deterrent to the full utilization of this resource is the fact that there are less than 10 botanists in the United States, 5 in Malaysia, and only two in Sarawak who are fluent in the flora of Borneo. The educational objectives of the project seek to widen the regional forest expertise of the resident researchers and technical staff, and thereby foster regional collaboration among a new generation of forest scientists. Dr. Ashton is a senior researcher with an excellent international reputation gained through some three decades of research on Bornean forests. Dr. LaFrankie is a young U.S. scientist who has been engaged in postdoctoral research in Borneo. Mr. Lee is Assistant Director of Research and Reforestation, Sarawak, Malaysia. Primary research support is provided through NSF Grant No. BSR-9107247, with matching funds from Japanese sources, notably, the Monbusho Fund and the Marubeni Corporation. This project is relevant to the objectives of the Science in Developing Countries Program which seeks to contribute to the infrastructure of developing countries and to increase the level of cooperation between U.S. scientists and engineers and their counterparts in developing countries through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit.