Community Composition, Tree Population Structure in a Temperate Broad-leaved Evergreen Oak forest along a Disturbance Gradient in Garhwal Himalaya, Uttarakhand, India

The present study was carried out in broad leaved evergreen oak forests of Garhwal Himalaya, Uttarakhand, India (1500-2100 m amsl.) along disturbance gradient. In this study, some disturbance indicators i.e. canopy cover, stand density, grazing intensity, lopping intensity, number of cut stumps and climber invasion have been evaluated and with the help of these indicators the forest area has been categorized into three categories viz. undisturbed, moderately disturbed and highly disturbed. The study revealed that tree diversity decreased with increasing intensity of disturbance in case of tree and herb species but it was found maximum in moderately disturbed stands for both layers (tree, herb) whereas, in case of shrub species, Shannon diversity increased with increasing disturbance level. Simpson dominance index was found as reverse of the Shannon index in all three layers of vegetation for all disturbance categories. Almost same trend was found in species richness. It was found more vulnerable to disturbance in case of tree and herb layers as it decreased with increasing level of disturbance but its highest values were recorded in the moderately disturbed stands in both vegetation layers. On the other hand shrub species richness favored the disturbance as it increased with increasing intensity of disturbance. As far as the regeneration is concerned, sapling and seedling density was decreased with increasing disturbance level but both the classes were found maximum in the intermediate level of disturbance. Diameter-density curves depicted a successive reduction in the number of trees from lower girth classes to upper. All the above variations in relation to species richness, distribution pattern and regeneration potential are related to anthropogenic interference.