Composition, diversity and distribution of tree species in response to changing soil properties with increasing distance from water source - a case study of Gobind Sagar Reservoir in India

Construction of big dams on rivers develops artificial lakes or water reservoirs which conceive alterations in soil properties of the upstream catchment area. An undulating topography and freckly soil properties cause ups and downs in tree diversity, composition and distribution. The study aimed to evaluate the effect of Gobind Sagar reservoir on soil properties relative to the distance from it and asess its effect on tree diversity, evenness and their distribution in tropical and subtropical forests. Based on data analysis it was found that the soil moisture and organic carbon decreased along with increasing distance from the reservoir. It played a significant role in varying tree diversity. The sites distributed within 0-2 km showed significantly higher a and beta-diversity indices. Tree species richness and diversity indices showed a strong correlation (p < 0.05) with soil moisture and organic carbon content. Simpson's and McIntosh evenness indices showed a strong negative correlation with soil bulk density. Indirect Detrended Correspondence Analysis (DCA) identified soil moisture and soil organic carbon as two major environmental gradients that influenced tree diversity and their distribution in five tropical and four subtropical forests in an upstream catchment of the reservoir. Mixed forests inhabited moist sites and Acacia-Pinus forests showed an inclination to dry areas. Canonical Correspondence Analysis (CCA) revealed that the tree species in tropical forests were mainly affected by driving forces such as soil moisture, organic carbon and bulk density whereas, in subtropical forest tree species were influenced by elevation, soil pH, EC and clay content.