The potential geographical distribution of Haloxylon across Central Asia under climate change in the 21st century

Members of Haloxylon are unique key species in the deserts of Central Asia (including Soviet Central Asia (SCA) and Xinjiang, China (XJ)). The region is a hotspot of global warming, and the plants’ habitats are threatened by climate change. By using normal-climate data and future climate projections from 17 general circulation models (GCMs), we herein simulate the present and future potential habitats of Haloxylon persicum (H. persicum) and Haloxylon ammodendron (H. ammodendron) in Central Asia using a Maximum Entropy (MaxEnt) model that was developed based on 307 specimen records of Haloxylon vegetation. The MaxEnt model showed high accuracy, with an average training area under the curve (AUC) value of 0.93-0.95. Our analysis indicated that temperature and precipitation play equally important roles in shaping the spatial distribution of these desert shrubs. According to the model estimates, the current (based on 1961–1990 climate normals) potential habitats of H. persicum and H. ammodendron are 1.56 × 106 km2 and 1.53 × 106 km2, respectively, mostly (93.1% and 75%, respectively) distributed in SCA. Model projections based on two future climate scenarios, namely, the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios (representing stabilized radiative forcing at 4.5 W m−2 and 8.5 W m−2 by the end of the 21st century, respectively), predicted that the potential habitat of H. persicum will increase by 44% (RCP4.5) to 62% (RCP8.5) but that the potential habitat of H. ammodendron will decrease by 22% (RCP4.5) to 34% (RCP8.5) in the late-21st century. The potential habitats of Haloxylon vegetation will gradually be lost in XJ but will expand in southwestern Kazakhstan circa 2041–2060 and 2061-2080. Therefore, it is advisable to protect the habitats of Haloxylon species in XJ (esp. southern XJ), where strong warming in the future might impose severe stress, and establish ecological corridors in central Uzbekistan and southern Kazakhstan to facilitate Haloxylon redistribution, as the geographical centroid of the Haloxylon habitats is shifting northward and westward in Central Asia.