مقالات انگلیسی
در حوزه خرس قهوه ای و خرسی سیاه آسیایی
Mehdi Ansari H., Arash Ghoddousi
Abstract: Large carnivores are among the most threatened species in the world because of their natural low densities and need for expansive habitats. The brown bear (Ursus arctos) is the largest carnivore in the southwestern Asia, and faces threats in much of its range from conflict with humans over shared resources and shrinkage of habitat. In this study, we surveyed for brown bear sign and scat during spring–autumn from April 2013 to November 2015 in 24 randomly selected, 25-km2 grid cells, and developed a model of potential brown bear occurrence in one of its globally southernmost distribution ranges in Iran. To better understand its conservation needs and management priorities at the landscape scale, we used a combination of field surveys to develop a Maximum Entropy (Maxent) model. The model was developed using 10 environmental and anthropogenic predictors. Potential brown bear occurrence was strongly influenced by availability of water resources (54.1%) as the most important variable; and distance to roads (16.1%), aspect (7.6%), and vegetation types (5.9%) were the other important factors. The model showed an area of 581 km2 (35%) within the study area has high to good bear-occurrence probability values; 86% of this area is located in 2 patches, each larger than the average bear home range. Identification of these patches may support establishment of a reserve in the area, which would ensure long-term survival of the brown bear and sustainable water use and resource extraction from Pistacia atlantica forests by resident and nomadic communities in the region.
Azita Farashi, Malihe Erfani | Department of Environmental Sciences, Faculty of natural resource and environment, Ferdowsi University of Mashhad, Iran | Department of Environmental Sciences, Faculty of natural resource, University of Zabol, Iran
Future changes in climate are imminent and they threat endangered and rare species due to habitat destruction. The Asiatic black bear (Ursus thibetanus gedrosianus) is a rare and vulnerable species whose habitat fragmentation and habitat loss decreased the size of its population significantly. Climate change is another threat to this species that is investigated in this research work. Aiming at this goal, ten species distribution models (SDMs) were applied as helpful tools for evaluating the potential effects of climate change in habitat suitability of Asiatic black bear in Iran. Potential dispersal of Asiatic black bear was modeled as a function of 32 environmental variables for the current time and 2070 for 44 climate change scenarios (CC scenario) of future climate. Our results showed that modeling results depended on type of model. Our results confirmed that one of the greatest threats in the near future for Asiatic black bear was the change of suitable habitat due to climate change. All the CC scenarios showed that migration of this species would be to the north and west areas with higher elevation and that an increase in area would be more than a decrease in area in all scenarios. Recognizing and protecting potential future habitats are of the important activities to conserve this species and identify areas with conservation priority