Differential vulnerability of key threatened mammals to climate and land cover changes in the Central Himalayas

Anthropogenic climate change affects biological diversity by altering their suitable habitat ranges. The Himalayan region is one of the world's most sensitive biodiversity hotspots to global climate change. The Chitwan–Annapurna Landscape (CHAL) in the Central Himalayas serves as a vital north‒south linkage among the protected areas in central Nepal, and provides suitable habitats for threatened mammals in different ecological zones, such as snow leopards (in the alpine zone), Himalayan red panda (in the temperate zone), and one-horned rhinoceros (in the lowland tropical zone). The biodiversity of CHAL is threatened by climate change and land use alterations. This study assessed the potential impacts of climate and land cover changes on the above three key threatened mammals in CHAL by employing maximum entropy (MaxEnt) modeling to predict the current potential habitat and project it for future climate change scenarios under different greenhouse gas concentrations. Further, we used the cellular automata and Markov-Chain models to simulate and predict the temporal and spatial changes in land cover of CHAL. Our results indicate that the snow leopard and Himalayan red panda will experience significant vulnerability than the one-horned rhinoceros in all future climate scenarios. Approximately 36.3% and 41.8% of the suitable habitat of the snow leopard and 32.5% and 56% of the Himalayan red panda in CHAL are projected to be lost in 2050 and 2070, respectively, under RCP6.0. Climate refugia, representing areas of suitable habitat for 2070 (under the RCP6.0) in CHAL, are projected to cover 958 km2 (80.37% of the current range), 1,052 km2 (43.73% of the current range), and 2,375 km2 (58.21% of the current range) for one-horned rhinoceros, Himalayan red panda and snow leopard, respectively. Among the land cover attributes in CHAL, snow cover is predicted to decrease by 24% in 2070. Our findings indicate that species inhabiting alpine and temperate environments are more susceptible to human-induced climate change than those inhabiting lowland tropical areas. These findings will help to implement the adaptation actions that are crucial to address future conservation challenges arising from climate and land cover change.

Methods
Occurrence records of the snow leopard, one-horned rhinoceros and Himalayan red panda were collected from the published literature, grey literature, national survey database, and field surveys (December 2019) (Ale et al., 2014; Bista et al.2016, Bista et al., 2017; Chetri et al.2019; Thapa et al. 2018b; Thapa and Puri 2019; DNPWC, 2009; DNPWC 2020).