Population Structure and Microhabitat Preference of the Himalayan Yew (Taxus wallichiana. Zucc) in Uttarkashi

Abstract

Understanding choices made by any species at a micro level is intrinsic to detecting patterns in ecological space. On the other hand, understanding how variations in micro site in turn affect the populations of any species is important in terms of ecological time. This study compares population structure of Taxus wallichiana. Zucc, a threatened medicinal tree endemic to Himalaya, across different habitat types and to studies micro site preferences (over space) exhibited by the species. The study maps the distribution of Taxus encountered and based on it, predicts areas which are likely to have Taxus. It also studies how differences in habitats affect the population structure of the species. Using generalized linear models, the microhabitat preferences of the species was modeled. This study is merely the preliminary to further insights to the species choices for a habitat and responses to habitat changes. The findings of the study are as below: 1. Population structure revealed significant differences between age class structure across habitat types (p<O.OOO I). Older age classes were found in association with Sub alpine forests while the younger classes were found more in Warm Temperate and Cool Temperate forests. 2. The sex ratio ofthe Population also varied across habitat types with a bias towards female individuals. This difference was significant at p<O.OOOI. 3. The age structure across different disturbance gradients varied significantly (p<O.OOO 1) with varying disturbance gradients.4. The potential distribution of Taxus was found to be dependent on the minimum temperature of the coldest month, elevation and the precipitation during the warmest month. 5. The microhabitat variables that influenced Taxus presence and abundance were found to be a combination of the slope, litter depth and the interaction between the aspect and temperature. 6. Associate species or immediate neighbor species of Taxus were found to be Abies pindrow, Quercus semecarpifolia, Picea smithiana and Quercus dilatata