Structure and Diversity of Seasonal Mixed Evergreen-Deciduous Tropical Forest, Western Thailand

Abstract

This paper describes the composition and structure of the tree community in mixed evergreen-deciduous forest with bamboo, at 700 m elevation in Thung Yai Naresuan Wildlife Sanctuary, western Thailand. This forest type covers large portions of western and northern Thailand but is little-studied. All trees with a diameter ≥5 cm diameter and bamboo clumps were identified, mapped and measured for diameter and height in a 1 ha (100 m × 100 m) plot. We recorded 330 individuals, 64 tree species in 36 families. The most common species were Colona floribunda Craib, Wendlandia scabra Kurz var. scabra, Castanopsis tribuloides (Sm.) A. DC, Schima wallichii (DC.) Korth. and Eurya acuminata DC. var. acuminata. Basal area was dominated by S. wallichii, C. floribunda and C. tribuloides. Canopy cover was 43% for trees only, but 75% when bamboo cover was included. Tree density was 19% lower within a 5 m buffer around bamboo clumps, with small tree distributions being more affected than large trees, strongly suggesting that bamboo suppresses tree recruitment. In comparison with other forests of similar origin, this plot exhibited lower tree stem density, abundant stems from deciduous, disturbance-specialist species, and abundant bamboo. These three factors likely reflect the influence of fire and possibly previous agriculture on the structure and composition of the plot. Monitoring of this plot and the surrounding area will provide important information about the trajectory of forest change. Because much of the forest at middle elevations in SE Asia is influenced by people, we encourage replication of quantitative forest monitoring at other sites.