Future potential distribution and expansion trends of highland barley under climate change in the Qinghai-Tibet plateau (QTP)

Highland barley is an important grain crop in the Qinghai-Tibet Plateau (QTP) of China. However, rare knowledge is available on the spatial pattern of habitat suitability across QTP and how it would be affected by future climate change. Based on 191 presence records, the probability of highland barley across the QTP under climate change is simulated by using the maximum entropy (MaxEnt) model. And the critical environmental variable (s) affecting the distribution of highland barley and the hotspots of habitat degradation/expansion during the 21st century are investigated. The results show that the daily minimum temperature of coldest month and annual precipitation are determined as the two most important environmental variables for predicting habitat distributions. Across the QTP, future climate change may result in an increase in the suitable area for planting highland barley northward, westward, and upward during the 21st century. Highland barley in river valleys of the southeastern and northeast plateau, where areas of medium and optimal suitable habitats are concentrated, may experience contractions in areas of habitat suitability during the 21st century. By the late 21st century, the average expansion and contraction of suitable habitat areas are 0.46 and 0.14 million km2, respectively, and the upper limit elevation suitable for planting barley may increase by 215 m. Our results could provide valuable distribution information to the national and local administrators for developing the special industry of highland barley in the QTP.