Species composition and distribution of tree in Dipterocarpus alatus Roxb. ex G.Don community and Hopea odorata Roxb. community of a riparian area along the Chao Phraya River

Abstract

This study examined the species composition and distribution of tree in D. alatus, and H. odorata community of the riparian area along the Chao Phraya River. Two hundred and fifty two of 0.1-ha circular plots were established in remnant forest patches of the riparian area along 372 km of the Chao Phraya river, passing through 11 provinces. The data were calculated the quantitative community characteristic such as species richness, tree density, tree basal area, importance value index (IVI), and the Shannon–Wiener index (Hʹ). Distribution of habitat suitability models in each community were analyzed by Geographic Information Model (GIS). The result showed that, the H. odorata community indicated all of quantitative community characteristic higher than D. alatus community. The dominant species of H. odorata community such as H. odorata, D. alatus, and Crudia chrysantha, and the dominant species of D. alatus community such as D. alatus, Ficus racemosa, and H. odorata. The physical factors were elevation, slope, aspect, distance from the river, convexity, rainfall, annual mean temperature, and distance from the sea shown significant affecting on the distribution of both community within the accuracy level of 82.0 % and 86.4 %, respectively. D. alatus community indicated the potential of habitat suitability in high, moderately, and low levels were 2,566,875 and 3,361,875 and 2,978,750 rais, respectively, while, H. odorata community indicated that high, moderately, and low levels were 1,906,875 and 3,423,125 and 3,577,500 rais, respectively.