Floristic Composition and Species Diversity of Wintering Herbs in Blue pine Forest of Thimphu District, Bhutan

Aims: This study was carried out to document wintering herbs species in the blue pine (Pinus wallichiana) forest of Kawang Gewog under Thimphu district, Bhutan. To generate baseline data on species diversity and composition of the winter herbaceous layer in the blue pine forests of the study area.

Study Design: To evaluate the floral diversity and composition of herbs, stratified random sampling was used.

Place and Duration of Study: The study was conducted in Thimphu district within the altitudinal range of 2400 m to 2700 m A.S.L. The fieldwork was conducted during the month of December to January 2019 and during March 2020.

Methodology: Four line transects were established randomly, with sampling points placed at 25-meter intervals along the transect. For adequate data collection, three 3X3 meter quadrats were laid along a straight line perpendicular to the transect, using species-area Type I curves (strictly nested curves). Each quadrat was then divided into 100 equal sub-quadrats, with a distance of 5 meters separating each quadrat.

Results: A total of 60 herb species belonging to 46 genera and 22 families. The Shannon-wiener index of species diversity (H’) showed 1.73 value suggesting higher diversity in the study site with an altitude of 2600 m to 2700 m compared to other sites with an altitude range of 2400 m to 2500 m, H’ value of 1.59.

Conclusion: The study conducted reports the finding on diversity and the composition of herbs occurring in the winter season from Kawang Gewog under Thimphu district. The present study also discusses the diversity and evenness of herbs influenced by elevation and anthropogenic influences.