J. Agrofor. Environ. 5 (special issue): 89-93, 2011 ISSN 1995-6983 Forest structure and species composition of seasonal flood forest along the Se Buy River in Yasothon Province, Northeast Thailand R. Yoneda1, S. Poungparn2, M. Sano3, R. Tabuchi4, P. Patanaponpaiboon2 1Bureau of International Partnership, Forestry and Forest Products Research Institute, (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki 305-8687, 2Faculty of Science, Chulalongkorn University, Bangkok 10900, Thailand, 3Department of Forest Management, Forestry and Forest Products Research Institute, (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki 305-8687 4Forestry Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Owashi, Tsukuba, Ibaraki 305-8686, Japan, E-mail:
[email protected] (e-maill address of lead author) Abstract: The structure and topography of seasonal flood forest, where was inundated from August to October, was studied at the Se Buy river in Yasothon Province, Northeast Thailand. Tree census has been conducted since 2005. Five hundred and ninety three trees and climbers were recorded and 70 species were identified in the 30m × 150m plot. Stand density, total basal area and the mean diameter at breast height (DBH) were 1317.8 trees/ha, 23.61m2/ha and 11.32cm, respectively. Mallotus thorelii (Euphorbiaceae), Garcinia schomburgkiana (Guttiferae), Hymenocardia punctata (Euphorbiaceae), Dipterocarpus alatus (Dipterocarpaceae) and Vatica harmandiana (Dipterocarpaceae) were abundant species in the plot. Riparian zone forest locating adjacent to the river was inundated for approximately 3 months, and consisted by small DBH trees of M. thorelii, G. schomburgkiana and H. punctata. Seasonal flooding might disturb the riparian zone frequently, and riparian zone forest consisted by pioneer species. Upper part of the plot, where was rarely flooded by special large flow, was mostly consisted by large DBH trees of Irvingia malayana (Irvingiaceae) and Shorea roxburghii (Dipterocarpaceae).