Biodiversity and global land-use change in Bhutan: a model for the Himalayas

The eastern Himalayas are a global biodiversity hotspot with one of the highest rates of species endemism. But a high rate of habitat degradation and loss fuelled by anthropogenic disturbance and climate change is besieging biodiversity. Understanding the interaction between biodiversity and land-use change is particularly important in the context of the eastern Himalayan landscape in the face of global climate change. However, a synthesis of combined impacts of land use and climate change on biodiversity in this landscape is surprisingly rare. This thesis aims to fulfil that gap. In Chapter 2, using multi-scale models for terrestrial mammal communities, I show that protected areas (PA) and forest cover are the two most important variables associated with habitat use of most modelled species. Further, I show that both carnivores and herbivores are equally important umbrella species. The gap analysis shows that existing PAs and areas adjacent to them are crucial for overall species richness protection. Chapter 3 uses two spatially synoptic methods (i.e., resistant kernel density and factorial least cost path) to identify core habitats and corridors for terrestrial mammal communities. I show that Asian elephant (Elephas maximus) was the most effective umbrella species for the overall protection of core habitats. In terms of dispersal corridor protection, muntjac was the most effective umbrella species. Using cluster analysis, I identified six indicator species (Asian elephant, Asiatic black bear [Ursus thibetanus], clouded leopard [Neofelis nebulosa], dhole [Cuon alpinus], sambar deer [Rusa unicolor] and tiger [Panthera tigris]) for broad core habitat and corridor protection. Here, I show that dispersal is not just limited within PAs and the long-term viability of wildlife populations require habitats and corridors outside the existing PA network. In Chapter 4, I show that the realised functional space of the vertebrate groups (mammals and birds) is clumped around a small number of functional strategies. The loss of species at the edge of functional space is non-random and could result in the loss of irreplaceable traits impacting long-term ecological and evolutionary processes. Further, this study demonstrates the filtering effect of anthropogenic pressure and climate change on vertebrate functional and phylogenetic diversity. Chapter 5 demonstrates the complex effects of human settlement density on large carnivore interactions. I show that space-use patterns are driven by a combination of the behavioural mechanism of each species and its interactions with competing species. The duality of the effect of settlement density on species interactions suggests that the benefits of exploiting anthropogenic environments are a trade-off between ecological opportunity and the risk of conflict with humans. Taken together, this thesis highlights the importance of eastern Himalayan biodiversity and the need for integrated and synthetic research across the Himalayas to better understand the effects of anthropogenic land-use and climate change on distribution, connectivity, and behavioural ecology of terrestrial vertebrates and on the multiple facets of biodiversity per se.

Keywords: biodiversity
Himalayas
land-use
Bhutan
Advisor: Macdonald, D