An Ecological Study in the Buffer Zone of the Corbett Tiger Reserve: Prey Abundance and Habitat Conditions

摘要

We studied prey abundance and habitat conditions in the buffer zone of the Corbett Tiger Reserve using a combination of sampling techniques based on direct and indirect evidences, langur (Presbytes entellus) and chital (Axis axis) were found to be the most abundant prey species in the buffer zone. The total prey biomass was estimated to be 2847 kg/km~2 and chital and sambar (Cervus unkolor) contributed 84% of it. Block-wise abundance of prey species based on the Forest Department data showed that 80% of the forest blocks had low prey biomass and these blocks were distributed in north. The density of chital estimated by line transect method appeared to be very high and was clearly an overestimate. The findings suggested that chital, nilgai and wild pig utilized areas with moderate to high levels of disturbance whereas sambar and barking deer showed clear avoidance for such areas. The forest in buffer zone was dominated by Shorea robusta with an IVI value of 98.2. The mean tree density was 279.7 trees/ha and it was highest in North Jashpur forest block. The highest shrub density was recorded in Nalkatta forest block. The estimates of mean density, diversity, richness and evenness for tree, shrub, grass and herb layers differed significantly between transects. The levels of disturbance factors especially, cutting, lopping, grazing and overall biotic pressure were found to range between low to high. There were 9 blocks in low, JO in medium and 7 blocks under high levels of biotic pressure. While attributes of tree and shrub layers showed no significant relationship with various disturbance factors except the proliferation of Lantana camara and other weed species in shrub layer, the attributes of grass and herb layer showed significant negative impact of disturbance factors in terms of reduction in grass and herb diversity, richness and evenness.