Niche width analyses facilitate identification of high-risk endemic species at high altitudes in western Himalayas

Abstract

High-elevation mountain communities are progressively threatened by habitat fragmentation and climate change resulting in habitat shift and biodiversity loss. Despite it, very few studies have focussed on niche distribution and diversity pattern of non-native and native plant species in high mountain communities, and their role in identifying endemic species with high extinction risk in Himalayas. To determine niche width and diversity pattern of species based on the nativity, and ascertain the role of niche width in conservation prioritization of endemic/native species, four sites were selected in western Himalayas. We analysed diversity indices (based on native, non-native, and total species) such as Species richness, Simpson index, Chao-1 index, Whittaker index (βw), and species niche width across the elevational gradient in study sites. Non-native species were found to thrive in lower elevations. The niche width of non-native species declined with increase in elevation, but a few non-native species had a broad niche width (habitat generalist). Such habitat generalist species may lead to the displacement of endemic or native habitat specialist species (having narrow niche width). Species like Aconitum heterophyllum, Aconitum violaceum, Bergenia stracheyi, Dactylorhiza hatagirea, Jurinea dolomiaea, Sinopodophyllum hexandrum, Morina longifolia, and Roscoea alpina etc. were found to have a narrow niche width. Such species will face an extinction risk due to the upward shift of non-native species. The high elevational plant communities are more susceptible to extinction risk due to the accelerated spread of non-native species influenced by climate change. This study emphasizes the crucial need to implement strategies for the control of non-native species, describing species compositional changes at higher elevations, and aids to efficiently identify and conserve native species under high extinction risk.