Species richness and diversity along the disturbance gradient in kedarnath wildlife sanctuary and its adjoining areas in garhwal Himalaya, India

Species richness, diversity and distribution pattern of tree species were studied along a disturbance gradient in three mixed broad leaved forests. The forests were selected on the basis of varying disturbance intensities and were categorized into highly disturbed (HD), moderately disturbed (MD) and least disturbed (LD). A total of 34 tree species (belonging to 30 genera and 21 families) were reported along the disturbance gradient. Both tree species richness and diversity markedly declined along the disturbance gradient from LD to HD forests. Maximum species richness (20) was reported from LD while minimum (11) from HD forest. Shannon Wiener index (2.30-3.34), Margalef’s index (2.59-4.11), Menheink’s index (1.60-1.99) were maximum in LD and minimum in HD forests. Species richness and diversity indices showed significant negative relation with disturbance. Diversity-dominance (d-d) curve showed high equitability in LD forest while high dominance in MD and HD forests. More than 90% of tree species showed contagious distribution that is the most common distribution pattern in nature but it did not show any definite trend along the disturbance gradient. Low maturity value and contagious distribution of species denote the early successional status of the studied forests. The present study reveals that the anthropogenic disturbance causes disruption of forest structure and changes species composition which ultimately leads to reduction of tree species richness and diversity which is a major forest component.