Effect of micro-environment and human disturbance on the diversity of woody species in the Sariska Tiger Project in India

Abstract

Species richness, diversity, basal cover and importance value index of the woody vegetation were analyzed in the Sariska Tiger Project in the north-eastern part of Rajasthan, NW India. Four study sites were selected on the basis of degree of human disturbance: (a) the Slopka forest (undisturbed), (b) the Kalighati forest (previously partially disturbed, now has been protected since 1979), (c) the Bharthari forest (partially disturbed) and (d) the Hajipur forest (highly disturbed). In the undisturbed Slopka forest, cumulative number of woody species increased from 20 in the valley to 38 up to the summit of hill slopes. The Shannon–Wiener diversity index and the Simpson's index were very low, i.e. 2.10 and 0.2, respectively. Observations on density, basal cover and IVI suggest that the elevation and various aspects of hill slopes maintain the rich species diversity of the woody vegetation in the severe arid climate of this forest. The anthropogenic disturbances have adverse impact on the woody vegetation. Species richness was higher in the undisturbed Slopka forest (38) as compared to the partially disturbed Bharthari forest (19). However, it was also relatively higher in the highly disturbed Hajipur forest (25). The diversity index of woody species was highest in the undisturbed forest (2.10) and lowest in the highly disturbed forest (1.6). Although the density and basal area of most of the woody species declined with increase in human disturbance, the density of dominant tree Anogeissus pendula increased from 1.6 in the undisturbed forest to 9.2 per 100 m 2 in the highly disturbed forest which suggests its high regeneration potential even in harsh environmental situations. Sorenson's index of similarity declined to 0.40 in the highly disturbed forest. The 0.63 similarity index between the vegetation of Slopka and Kalighati forest indicates that the original species composition of the undisturbed natural forest may not be restored once changed by human disturbance.