THAI FOREST ECOLOGICAL RESEARCH JOURNAL
This study was conducted to evaluate structure and composition of tree species in the deciduous dipterocarp forest where Calamus acanthophyllus was found. Three studied areas with different degrees of disturbance was selected, including, protected fire area (plot 1), reestablished area from farming activity (plot 2), and non protected fire area (plot 3). The permanent plot, 50 x 100 m, was set up in each area. In each plot, all trees with diameter at breast height (DBH) over than 1 cm were identified and measured of DBH and height of randomly selected trees, including the position of all trees were also recorded. In addition, diameter at root collar and height of C. acanthophyllus were measured. It was found that tree density and total basal area of plot 1, 2 and 3 were 1,284, 1,196 1,842 stands/ha, 6.96, 7.93, 8.01 m2/ha, respectively. Plants with the highest Importance Value Index (IVI) for plot 1, 2 and 3 were Tectona grandis Linn.f., Dipterocarpus tuberculatus Roxb. and D. tuberculatus Roxb., with the IVI of 86.23, 188.88 and 112.86 %, respectively while numbers of plant species and diversity index (Shannon-Wiener index) were 19, 17, 23 species and 1.59, 1.16, 1.485, respectively. Distribution of trees among different DBH classes for plot 3 was found to be in a negative exponential form indicating that the forest in this plot was in a reestablishment stage. Relationship between DBH and height in form of hyperbolic equation yielded the highest Hmax in plot 1 at 18.44 m. In terms of C. acanthophyllus ecology, it found that the average diameter at root collar, average height, and maximum height in all plots were statistically different. It maybe concluded that area management and/or degree of disturbance from both from human activities and fire could have an impact on number and growth of C. Acanthophyllus.
Keywords: forest structure, species composition, deciduous dipterocarp forest, Calamas.