The relationship of Himalayan Yew (Taxus baccata L.) with Other Plant Communities and Environmental Factors in the Western Part of Bhutan
Damber Mani Rai, Nantachai Pongpattananurak, Roongreang Poolsiri, and Chatchai Ngersaengsaruay
Taxus baccata L. is a rare and lesser known tree species with important medicinal values. However, very sparse data, related to its occurrences in western Bhutan, is available. In this study, the distribution and abundance of the species was determined in relation to the environmental
variables (soil nutrients, soil texture, and topography), through the non-aligned systematic sampling method. The data were analyzed using multivariate and univariate statistical techniques. The study recorded 48 tree species under 21 families, from 70 sampled plots. T. baccata was present only
in 10 plots, where 28 tree species under 15 families were recorded. In the plots with T. baccata , the tree species with higher importance values were T. baccata, Rhododendron arboreum, Quercus lamellosa, Acer campbellii, and Tsuga dumosa, whereas the species with a higher basal
area were T. baccata, Tsuga dumosa, Quercus lamellosa, Acer campbellii, and Rhododendron arboreum. The means of environmental variables between plots with and without T. baccata showed a highly significant difference for the potassium content and elevation, whereas the soil
texture variables did not show any significant differences. Logistic regression analysis of all the covariates indicated that sand and magnesium level, elevation, and aspect as being somewhat significant for the presence of T. baccata. In contrast, the calcium content had a negative influence
but was not significant for the presence of T. baccata. The study indicated that the occurrence of T. baccata was dependent on specific environmental factors. This information will be useful for the ecological management of the T. baccata species in Bhutan.