POPULATION STRUCTURE AND REGENERATION OF QUERCUS SEMECARPIFOLIA IN LANGTANG NATIONAL PARK AND ITS BUFFER ZONE, CENTRAL NEPAL

Abstract

This work was carried out to study the forest composition, population structure, regeneration of Quercus semecarpifolia and disturbances at Langtang National Park and its buffer zone. The vegetation data were collected from total of 77 circular plots of radius 10m for tree species of which 40 plots were established at National Park area and 37 plots were established at buffer zone area. Importance Value Index (IVI) of tree species, distribution pattern of seedlings and saplings, and soil attributes were analyzed. Regeneration was assessed by density-diameter curve. Seventy seven soil samples were taken for laboratory analysis. A total of 9 species of trees belonging to 8 families were recorded from National Park and 17 species of tree belonging to 14 families were recorded from its buffer zone. The most frequent and dense tree species in the forest was Quercus semecarpifolia with important value index of about 30.23% (IVI= 90.69) inside National Park and the value was about 28.82% (IVI= 86.46) in buffer zone. The tree density of Quercus semecarpifolia in the National Park forest area was 158 stem/ha and in buffer zone was 248 stem/ha. Seedling and sapling density of Quercus semecarpifolia in the National Park forest was 166 stem/ha and 21 stem/ha and inside buffer zone, the values were 59 stem/ha and 53 stem/ha respectively. The density of tree at (30-49.9cm) DBH class was maximum and the highest DBH class had no individuals inside National Park while the density of tree of DBH class (10-24.9cm) was maximum and that of DBH class (160-174.9cm) was minimum in buffer zone. The density of tree at (5-9.9m) height class was maximum and the height class (<5m) had minimum density inside National Park while the value were maximum at (10-14.9m) and minimum at <5m in buffer zone. Q. semecarpifolia inside National Park showed a positively skewed distribution pattern and fluctuating distribution pattern in buffer zone. Disturbance was the main factor for unequal distribution and regeneration of species in study sites. Canopy cover, litter depth, soil nutrients and pH of soil showed positive correlation but insignificant relationship with seedlings and saplings growth. The disturbance index of buffer zone was higher (2.028%) compared to National Park (0.738%). The regeneration was found to be higher in the National park than the buffer zone and canopy cover was found to be most important factor for regeneration.