Ecological niche modeling as a cumulative environmental impact assessment tool for biodiversity assessment and conservation planning: A case study of critically endangered plant Lagerstroemia minuticarpa in the Indian Eastern Himalaya.

Cumulative environmental impact assessment (CEIA) at river basin level for hydroelectric projects is an evolving concept and has proved to be a useful tool to assess the cumulative impact of developmental projects on the natural ecosystems. However, the generality of CEIA studies is often contested because of methodological limitations, especially in the domain of biodiversity conservation and conservation planning. Ecological niche modeling (ENM) can be a useful tool in CEIA studies for conservation planning of threatened plants in hydroelectric project (HEP) areas. We elucidate this hypothesis taking the example of Lagerstroemia minuticarpa Debberm. ex P.C. Kanjilal, a critically endangered tree species in the Indian Eastern Himalaya. Standard ecological methods were employed to document occurrence records, estimate population size, and characterize habitats. ENM was used to estimate the species potential environmental niche and distribution areas. The possible impacts of HEPs on the potential habitats were predicted by overlaying the HEPs on the potential area map as well as using the conceptual network diagram. The study revealed that the species occupies an environmental niche characterized by humid to per-humid conditions, and is distributed mostly in the Lohit and Teesta basins. Potential areas of the species with high environmental suitability coincide with 19 HEPs, which point to a potential threat to the survival of the species. Network diagram indicated that project activities might deteriorate the habitats thereby affecting the population and regeneration of the species. Our study provides a framework for developing appropriate measures for species conservation and reintroduction at basin level using ENM.