Variations of Plant Species Diversity along Altitude Gradient in Conservation and Utilization Community Forests at Nong Tao Village, Mae Wang District, Chiang Mai Province

Abstract

            Variation of plant species diversity along the altitude gradient in the conservation (CF) and utilization (UF) forests of Nong Tao village, Mae Wang district, Chiang Mai province was investigated. Fifty plots of 40 x 40 m were stratified random selected along the latitudinal gradient from 1,000 to 1,800 m m.s.l. in each vegetation type (total of 100 plots). Stem girth at 1.3 m above ground, crown width and height of all tree species with >1.5 m height were measured in all plots. The total of 256 tree species (166 genus, 73 families) were found in CF, and 132 species (93 genus, 52 families) in UF. Dominant species in CF are Pinus kesiya, Schima wallichii, Castanopsis diversifolia, Lithocarpus thomsonii and C. accuminatissima. The Fagaceae family has a highest species richness (21 species), following by Euphorbiaceae and Leguminosae (16), Rubiaceae (15) and Lauraceae (12). P. kesiya has a dominated frequency of 58%, therefore this vegetation type should be classified as the pine-lower montane forest (LMF), and the remainder (42%) of non-pine should be classified as the lower montane forest. Tree density is 314+2.78 trees/rai in average. P. kesiya has a highest important value index (IVI), and following by S. wallichii, C. diversifolia, Lithocarpus thomsonii, Wendlandia tinctoria and Styrax benzoides, respectively. Species diversity index (SWI) per plot is 4.49+0.64 in average, with forest condition index (FCI) of 17.3+6.87. In UF, Fagaceae has the highest species richness (16 species), and following by Euphorbiaceae and Rubiaceae (10) and Lauraceae (6). P. kesiya has the high frequency (98%) that indicated to the pine-LMF, and the remainder (2%) is LMF. The tree density is 388+9.82 trees/rai. Quercus brandisiana has a highest IVI, and following by P. kesiya, Tristaniopsis burmanica and C. accuminatissima. The SWI is 3.43+0.50 with FCI of 10.54+4.60. Tropical tree species population decreases as increasing altitude whereas temperate species are abundant in the higher altitude of CF and decreasing in UF. Number of species, genus, family, species diversity index, stem basal area and crown cover in CF are higher than in UF with variations along the altitude gradient. Original plant communities in UF had somewhat difference from CF, and timber utilization by selective tree cutting resulted in the lower species diversity.

Keywords: community forest, plant species diversity, montane forest, plant spatial distribution