Suitable habitat prediction and overlap analysis of two sympatric species, giant panda (Ailuropoda melanoleuca) and asiatic black bear (ursus thibetanus) in Liangshan Mountains

Abstract

Understanding spatial distribution and habitat overlap of sympatric species is essential to developing integrated policies for conserving species and regional biodiversity. This study combined data from the 4th National Survey of giant panda (Ailuropoda melanoleuca) and long-term field survey. We used the Maximum entropy model (MaxEnt) to predict the distributions of two sympatric bears, the giant panda and Asiatic black bear (Ursus thibetanus) in Liangshan Mountains. Based on spatial distribution of two species, we measured habitat fragmentation and spatial overlap of habitat use, and assessed environmental requirements of both species. Our results indicated that: (1) both species had similar distributions of suitable habitats, both were mainly distributed on the ridges of Liangshan Mountains. The suitable habitat area of giant panda and black bear were 1,383.84 km 2 and 2,411.49 km 2 , respectively. (2) The habitats of both species were fragmented and separated into many patches. However, habitat connectivity for the black bear was better than for giant panda. (3) Niche overlap indices, calculated by ENMTools, showed that two species have high overlap in their ecological niche (D = 0.654 and I = 0.901). The overlapping habitat comprised 958.29 km 2 of the study area, which contained 69.25% of giant panda habitat and 39.74% of black bear habitat. (4) We used permutation techniques to estimate the importance of environmental variables in the MaxEnt model. Distance to residents and altitude were the most influential predictors for both species. Vegetation types and mean temperature of coldest quarter were the third and fourth important predictor for giant panda, while annual maximum enhanced vegetation index (EVI) and distance to roads was important for the black bear. To protect these two species more effectively, a series of measures have to be adopted, such as strengthening vegetation restoration, controlling disturbance, and enhancing connectivity between habitat patches. We recommend that a systematic, multi-species conservation plan should be developed.