Impacts of climate change and human activities on saline vegetation-an example of Tamarix chinensis

Tamarix chinensis Lour. is widely distributed in the northern region of China, which not only has ecological values such as managing salinization and preventing soil erosion, but also possesses high medicinal and economic values. Integrating the theories and techniques of geographic information systems (GIS), remote sensing, species distribution models, and ecological niche modeling, we established the optimized MaxEnt model based on the ENMeval package, and simulated the potential distribution areas of T. chinensis in modern and future different climate scenarios by employing 371 distribution records and 13 environmental variables. We used 371 distribution records and 13 environmental variables to simulate the potential distribution areas of T. chinensis under different climate scenarios in the modern and future. The contribution rate of the environmental factor variables and the knife-cut test were used to evaluate the important factors constraining the potential geographic distribution of modern T. chinensis, and to quantitatively assess the potential geographic distribution area and size of T. chinensis under threat. The results showed that: (1) RM = 1.5 and FC = LQHPT were the optimal model parameters, the mean value of AUC was 0.906 ± 0.005, and the credibility of the model prediction results was high, the area of the potentially suitable area of modern T. chinensis under the influence of environmental factors only was 32.69×10⁵ km², and the area of the suitable area under the influence of human activities was 28.48×10⁵ km². (2) The area of the potentially suitable area of T. chinensis under the modern Highly suitable areas are concentrated in Xinjiang, northeastern Gansu, western Inner Mongolia, northern Ningxia, southeastern Beijing, Tianjin, eastern Hebei and northern Shandong. Mean annual air temperature (Bio1), coefficient of seasonal variation of air temperature (Bio4), alkalinity (ESP), distance from rivers, and mean annual sunshine hours are the main environmental factors governing the distribution of T. chinensis. (3) The geographical distribution range of T. chinensis varies in each period, and the mean center of T. chinensis distribution moves southeastward under the future climate scenario, with Xinjiang, Gansu, western Inner Mongolia, northern Qinghai, western Hebei, and northern Shandong being stable and suitable areas for T. chinensis. As global warming intensifies and human activities continue to increase, this study has implications for the conservation of T. chinensis under various climate scenarios in the future.