Effects of Climate Change and Grazing Pressure on Shrub Communities of West Asia, the case of Atriplex leucoclada community in the Syrian Rangelands

Abstract

Climate change has been considered a primary global environmental threat that will alter the distribution and abundance of plant populations worldwide. As a result, ecological models provide valuable insight into the potential impacts of climate change on plant community dynamics across diverse ecosystems, including semi-arid rangelands. The purpose of this study is to evaluate the vulnerability of the ecologically and economically important rangeland shrub, Atriplex leucoclada (Boiss) to both climate change and livestock grazing, within the Syrian rangelands as a representative landscape type of West Asia. Ecologically-based quantitative niche models were developed for both shrub species using Maximum Entropy (MaxEnt) and thirteen spatially explicit GIS-based layers to predict current and future species distribution scenarios. Data used in model development included climatic (8), soil (3), altitude (1), and grazing pressure (1) variables. Climatic variables varied over time in line with the predictions created from the HADCM3 global circulation model. Results indicate that with grazing and climate change, the distribution of A. leucoclada will be reduced by 54% in 2050, with the mean annual and minimum temperatures of the coldest month having the highest contribution in the model (28.7 and 21.2% respectively). The contribution of the grazing pressure, expressed by the overgrazing index, was estimated at 8.2%. Therefore, these results suggest that the interaction of climate and increased grazing has the potential to reduce the distribution of preferred plant species on western Asia rangelands.