Quantitative Analysis of Tree Species Diversity in Different Oak (Quercus spp.) Dominated Forests in Garhwal Himalaya, India

Himalayan broad-leaved forests are mainly dominated by oak (Quercus spp.) species. Oak species with other tree species provide numerous ecosystem services and serve as lifeline for local inhabitants. Overall tree diversity and their status in different oak dominated forests viz., Quercus leucotrichophora (1500-2200 m), Q. floribunda (2201-2700 m) and Q. semecarpifolia (2701-3300 m) were studied in Garhwal, Himalaya. A total of 54 tree species (40 genera) in Q. leucotrichophora, 43 tree species (30 genera) in Q. floribunda and 23 tree species (16 genera) in Q. semecarpifolia dominated forests were recorded. Lauraceae was the dominant family in Q. leucotrichophora and Q. floribunda forests (6 and 8 species respectively), while Ericaceae (3 species) was the dominant family in Q. semecarpifolia dominated forests. Pinaceae and Taxaceae were only two gymnospermic family represented by Pinus roxburghii at low, Abies pinrow at mid, Abies spectabilis and Taxus wallichiana at higher elevational oak forests. There was no significant variation (p=0.8) between overall tree density in different oak forests which ranges from 337±51 individual/ha in Q. semecarpifolia to 433±92 individual/ha in Q. leucotrichophora forests. The seedling density has significant variation (p=0.01) in different oak forests where highest density was recorded in Q. leucotrichophora forests (1981 individual/ha) and lowest in Q. semecarpifolia forests (348 individual/ha). The Total Basal Area (TBA) reported from Q. leucotrichophora (88.06 m2/ha) and Q. floribunda (110.5 m2/ha) forests was higher than those of earlier reported from the region, while basal area of Q. semecarpifolia (90.16 m2/ha) was comparable with the forests of western Himalaya.