Climate and land use changes shift the distribution and dispersal of two umbrella species in the Hindu Kush Himalayan region

Biodiversity loss from climate and land use change is a global occurrence, but is of particular concern in more prominent biodiverse and sensitive areas such as the Hindu Kush Himalayan (HKH) region. This region harbors two species of geographically separated brown bear (Ursus arctos) - the Tibetan (U. a. pruinosus) and Himalayan brown bear (U. a. isabellinus). Both serve as important umbrella species, providing many ecological benefits to their surrounding ecosystems. However, how these two species from the same taxonomic group but with distinct geographical ranges, will respond to climate and land use change is poorly understood. The aim of this study was to predict the potential impacts of future climate and land use change on the distribution and dispersal paths of Tibetan and Himalayan brown bears in the HKH region. We applied MaxEnt modeling to predict the distribution of the two bear species both currently and for the year 2070, using three General Circulation Models and three scenarios of climate and land use change. We then identified potential dispersal paths using Circuit Theory. Results showed that both species would be negatively affected by the climate and land use change expected in the 2070s. In all three climate scenarios, their distribution areas would both shrink and shift to higher altitudes. Throughout the HKH region, Tibetan and Himalayan brown bears were predicted to lose over 34% and 32% of currently inhabited area under the most severe climate scenario, respectively. In addition, results showed that the density of dispersal paths for Tibetan brown bear would decrease while dispersal resistance would increase, and that dispersal paths for Himalayan brown bears would shift to higher latitudes. To protect these species, the currently suitable distribution areas and dispersal paths should be considered as priority protected areas. Our findings provide a scientific basis for allocating protected areas in the HKH region that are effective under the context of global climate change, and for establishing transboundary cooperation in the HKH region.