Plant diversity in two forest types along the disturbance gradient in Dewalgarh Watershed, Garhwal Himalaya.

摘要

This study deals with the plant diversity and effects of disturbance on two types of forest namely, Anogeissus latifolius mixed forest (700-1200 m asl) and Quercus leucotrichophora forest (1500-2200 m asl) in Dewalgarh Watershed in Pauri District of Uttarakhand. Undisturbed, moderately disturbed and highly disturbed stands were identified within both types of forest of the watershed on the basis of canopy cover percentage, tree density ha-1 and cut stumps analysis. For Q. leucotrichophora forest, the undisturbed forest stand had canopy cover >60%, cut stump index <2 and 2144 trees ha-1, whereas the highly disturbed stand had canopy cover <49%, cut stump index >7 and 804 trees ha-1. For A. latifolius mixed forest, the undisturbed forest stand had canopy cover >45%, cut stump index <2 and 1275 trees ha-1, whereas the highly disturbed stand had canopy cover <38%, cut stump index >7 and 845 trees ha-1. The moderately disturbed stand occupied the intermediate position with respect to these parameters for both types of the forest. The study showed that the moderately disturbed stand favoured density and species richness in both the forest types. The Margalef index, Shannon diversity index and evenness index exhibited a similar trend, the highest value in moderately disturbed stand and lowest in highly disturbed stand. A sharp decline was recorded in tree density and basal area with increasing disturbance magnitude in both types of forests.