Tree Distribution across the Forest Ecotone of Lower montane Forest at Doi Sutep – Pui National Park, Chiang Mai Province

Abstract

            Tree distribution across the forest ecotone of lower montane forest (LMF) was carried out at Doi Sutep – Pui National Park, Chiang Mai province during 2014. The objectives aimed to clarify the species composition and determine environmental factors for tree species coexisting. Permanent transect plot, 30 × 600 m, was established from 900 to 1,100 m above mean sea level, and subplots, 10 m x 10 m, were divided with total 180 subplots. All trees with diameter at breast height, DBH, ≥ 4.5 cm were tagged, measured and identified. Soil moisture content and elevation were recorded in every subplot.

            The result showed that high tree species number was found 192 tree species in 126 genera and 56 families, while, the density and basal area of tree with DBH ≥ 4.5 cm were 1,220 individual.ha^-1 and 28.60 m².ha^-1, respectively. The dominance tree species based on importance value index (IVI) were Quercus brandisiana, Dipterocarpus obtusifoliu, Schima wallichii, Wendlandia paniculata and Litsea martabanica with IVI of 31.52, 18.40, 15.34, 15.31 and 13.32 %, respectively. The ordination analysis showed that the elevation and soil moisture content factors were the importance factors for determine tree distribution across forest ecotone. High elevation is dominance by the species of lower montane forest; in contrast, low elevation and soil moisture content are occupied by the deciduous dipterocarp forest (DDF). In addition, high moisture content was found at the forest ecotone where facilitated to support coexisted species both LMF and DDF such as Dipterocarpus obtusifolius, Wendlandia paniculata, Castanopsis tribuloides and Litsea martabanica etc. They can be used as indicator species on environmental change, especially drought conditions. Drought ecosystem may be shifted to high elevation when the areas were faced to the global climate warming.

 Keywords: Tree distribution, Forest ecotone, Deciduous dipterocarp forest, Montane forest,

                  Doi Sutep-Pui