Assessment of micro-habitat of woodland diversity in mountainous urban tract of Gangtok Town, Sikkim

The present paper deals with identification, delineation and ecological assessment of micro-habitats in Gangtok municipal area of Sikkim Himalaya. Long continued urbanization and tourism activities have been responsible for fragmentation and deterioration of the original woodlands of this mountainous area. Ecological surveys have been carried out along quadrats and transect to evaluate each of the habitat types in terms of species diversity and species richness. Results show that the Marglef’s Index, has received highest value (4.03) for the woodlands of Ranipol locality, located at the lower part of the study area, where more than 19 plant species have been enumerated. The lowest (1.89) value of the index has been obtained in case of Lower M.G. road woodland habitat located as the middle slope of the spur over which the Gangtok urban area extends. Closely similar results have been obtained from computation of Menhinick’s Index, value of which ranges between 0.02 and 0.09. Highest species dominance (Simpson’s index value = 0.90) and species diversity (Shannon’s index value = 0.83) have been found in case of Tadong woodland area while the lowest value of 0.47 for both the indices has been obtained for M.G. road. In Gangtok Municipal area the most dominant species is Dhupi (Cryptomeria japonica) particularly abundant in the upper part of the area namely in Burtok and Chandmari. In the middle part, namely in Deorali and Lower M.G. Marg the dominant species is Chilouni (Schima wallichii) and in the lower part i.e. in Ranipol and Tadong the dominant species is Utis (Alnus nepalensis). This study suggests that the distribution of species and species richness of different micro-habitat are largely regulated by altitude, climatic condition and topographic factors.