Climate driven elevational shifting of plant distributions in the selected sites of Siwaliks of North Western India

Abstract

Mountain biodiversity faces significant threats from climate change with uncertain consequences on species distributions and ecosystem integrity. Understanding the patterns and dynamics of species distribution is critical for managing and safeguarding biodiversity in a changing environment. Therefore, this thesis investigates plant distribution patterns, determinants, and dynamics along elevational gradients in the Western Himalayas. Following a macroecological approach, this research analysed a database for the elevational distribution of over 1000 plant species from three protected areas in the Western Himalayas. Using an ensemble MaxEnt modelling, this study predicted future shifts in suitable habitats for ten dominant tree species under various climate scenarios. The results showed that elevational patterns of species richness varied across study sites and indicated substantial deviations from the mid domain effect null model predictions. The interacting effects of climate, energy, and water availability emerged as key determinants of species richness. Direct effects of climate were stronger than indirect effects, and water energy dynamics mediated the indirect effects more strongly than the energy availability. About half of the investigated tree species can face range contractions, while others may move upslope. All studied species, except Shorea robusta, are predicted to lose their suitable habitats under future climates. These findings pave the way for prioritising conservation efforts and developing management plans to mitigate the impacts of climate change. Further, insights into future trajectories can inform targeted conservation strategies and develop plans to sustain the Himalayan trees in a changing environment. newline