Predicting the current and future suitable habitats of the main dietary plants of the Gobi Bear using MaxEnt modeling

Ephedra equisetina, the Nitraria species complex (N. sibirica, N. roborowskii and N. sphaerocarpa), and Rheum nanum are the main dietary plants of the Gobi Bear (Ursus arctos gobiensis), a subspecies of the brown bear, found in the Gobi desert of Mongolia. Their location and distribution range are closely related to the Gobi Bear survival. Analyzing the impact of climate change on the possible distribution of these species is essential for the future conservation and management of the Gobi Bear. In this study, we modeled the current and future distribution of the main dietary plants of the Gobi Bear based on one representative concentration pathway (RCP2.6) for the period from 2041 to 2060 (2050s) and 2061-2080 (2070s) using a maximum entropy (MaxEnt) species distribution model. Our results showed that the precipitation-associated variables had the strongest effect on the distributions of these species. Among these variables, the precipitation of the coldest quarter (Bio19) was the most important variable affecting the suitability of the habitats. Under the current climate conditions, the areas of the highly suitable (>0.6) habitat for E. equisetina, the Nitraria species complex, and R. nanum were 3,888.51, 23,727.78 and 13,816.88 km(2), respectively, accounting for 8%, 52% and 30% of the Great Gobi "A" Strictly Protected Area. In the year 2050s and 2070s, the highly suitable habitat areas for E. equisetina and R. nanum will continue to increase and eventually reach to 23% and 36%, respectively. The Nitraria species complex would first be reduced to 33% in the 2050s and then increase to 36% in the 2070s. With the climate warming, the highly suitable habitats of the Gobi Bear's main dietary plants would shift to the southeast. These results, together with previous studies about the Gobi Bear distribution can provide useful information and a reasonable reference for managers to put forward suggestions for better protection of the Gobi Bear. (C) 2020 The Authors. Published by Elsevier B.V.