Diversity pattern of vegetation in and around proposed Kotlibhel hydroelectric project along the Alaknanda River in Garhwal Himalaya (India)

Abstract

The study made an assessment of the floral status of the project site of Kotlibhel hydrolectric project (Stage 1B) at Alaknanda valley in the Ganga river system (India). Study area included two broad zones: Influence (IZ) and Submergence zone (SZ). Influence zone showed higher species richness in all vegetation strata. In the upper layer, there were 26 tree species, middle layer consisted of 32 shrub species and ground layer (understory) contained 41 species. Maximum density in the tree layer (36.4 plants/ha) was found for Haldinia cordifolia in the Influence zone. On the other hand, shrub and herb species showed highest density in the Submergence zone. Highest density of shrubs species was recorded for Ficus hederacea (844.0 plants/ha), while highest density of herbs for Desmodium triflorum (5540.1 plants/ha). Significant differences in Shannon diversity were found between Influence and Submergence zones for shrub and herb species (P<0.001), but not for trees. Simpson diversity was not significantly different for tree, shrub and herb species in both zones. Differences in Margalef species richness were found (P<0.001) for all vegetation layers in both zones. Distribution pattern of the species showed contagious patterns for both Submergence and Influence zone. Maximum Shannon diversity (3.561) was recorded in the Influence zone for herb species, followed by shrubs species (3.184) and tree species (2.593). Submergence zone showed lower Shannon diversity than the Influence zone, where a higher Shannon diversity (3.480) was recorded for herb species. Pinus roxburghii showed the highest IVI in the Influence zone (71.88) and Mangifera indica in Submergence zone (58.77).