COMMUNITY STRUCTURE AND REGENERATION OF Abies spectabilis D. Don IN SHAILUNG, CENTRAL NEPAL

Abstract

Community structure and regeneration of Abies spectabilis (D.Don) was studied in Abies spectabilis forest located in Shailung, Dolakha. Vegetation sampling was done by circular plot (20m diameter) method and the sample plots were located by systematic random sampling method. Two sites, northern and aspect, were selected for the study. Four horizontal transects running parallel to each other of about 200m altitudinal difference were designed for each aspect. Altogether 48 plots, six in each transect were established and the aerial distance between the plot was 50m. Number of woody plant species, number of individuals of each tree species, diameter at breast height (DBH) of each individual tree, number of seedlings and saplings of tree species were recorded in each plot. Various community attributes and population characteristics were analyzed. From each horizontal transect, soil was collected by pairing of plots in each transect from a depth of 30cm and pooled together. Three soil samples of 200 g from each transect were collected and their physicochemical characteristics were analyzed. On the basis of IVI Tsuga dumosa was dominant on lower elevation range on both aspects, while Abies spectabilis, was dominant at elevation range 2650m-2850m and 2850m-3050m, whereas, R. arboreum was dominant at elevation range above 3050m in northern aspect. Similarly, A. spectabilis and T. dumosa showed nearly equal dominance at elevation range 2650m-2850m, while A. spectabilis was dominant at elevation range 2850m-3050m and above 3050m in southern aspect. Altogether 40 plant species (13 tree species and 27 plant species in shrub layer) were found in the study area. The tree density of both sites increased with increase in elevation up to 2850m 3050m and decreased. Similarly, the basal area of tree gradually decreased after elevation range 2650m-2850m in both aspects. Comparatively tree density was higher in northern aspect and basal area was higher in southern aspect. Soil was slightly acidic in nature. The distinct variation in soil parameters were not observed in two sites as well as along altitude. Density-diameter curve of all tree species showed sustainable regeneration. But, density-diameter curve of A. spectabilis in both aspects slightly deviated from reverse J shaped structure and hence did not show sustainable regeneration. Seedling density was higher than sapling density. The distribution of seedlings and saplings were not uniform.