ANTHROPOGENIC PRESSURE ON TREE STRUCTURE AND BIOMASS IN THE TEMPERATEFOREST OF MAMLAY WATERSHED IN SIKKIM

Tree structure and composition, regeneration, biomass status and remov al as fodder, fuel and timber were studied in a temperate forest of th e Mamlay watershed in Sikkim Himalaya. The forest showed a high divers ity having 81 tree species, Castanopsis tribuloides and Quercus lamell osa being the most dominant canopy species in almost all areas of the forest. The forest has a good density (675 trees ha(-1)) and basal cov er (84.8 m(2) ha(-1)) and thus has a comparable range to other Himalay an forests. However, out of 81 tree species, just 39 were found regene rating and most of the canopy species showed poor regeneration. No see dlings and saplings for the other 42 tree species, which mainly includ ed canopy species, were found and this is attributed to intensive use of the forest for fuel, fodder and timber collection purposes. At the same time, regeneration of most of the secondary species, like Eurya a cuminata, Symplocos theaefolia, S. sumuntia, Leucosceptrum canum etc., was found to be fairly good at almost all sites. It is evident from t he present study that only secondary species are performing well under the existing levels of pressure in the forest floor phytomass. Annual net primary productivity was 8.32 t ha(-1) for wood biomass and 1.80 t ha(-1) for floor phytomass. About 35% of wood and 60% of floor phyto mass productivity has been removed by villagers annually, and this pra ctice of extraction has been highly erratic. It is presumed that, with a further increase in population of the surrounding villages of the w atershed, in the near future forest resources will become more desirab le and many species are likely to disappear in due course. Intensive a wareness programmes, with regard to resource utilization and managemen t, for both villagers and officials, can help to protect the forest of this unique diversity.