Abstract: As climate change continues to reshape ecosystems worldwide, understanding its impact on species distribution becomes crucial for effective conservation and management. In this study, we predicted the potential distribution area of an important native grass species in China, Elymus nutans Griseb., with an optimized MaxEnt modeling approach. Main aims of this study were: (1) exploring the distribution of Elymus nutans in different climate scenarios; (2) identifying the essential environmental factors influencing its geographical range and suitable habitats; (3) assessing the contraction, expansion, and stability of Elymus nutans’ range under future climate scenarios, and tracking the shift in its centroid under various climate scenarios. The results show that the potential distribution area of Elymus nutans is approximately 337×10⁴ km², accounting for 35.1% of the total national area. This species is primarily distributed in the western and northeastern China, including western Sichuan Province, most of Qinghai Province and Xizang Autonomous Region, the southwestern part of Gansu Province, the northwestern part of Xinjiang Autonomous Region, and the eastern part of Inner Mongolia Autonomous Region. There is also a significant distribution in the northern part of Shanxi Province, Jilin Province, and Heilongjiang Province. The entire potential distribution area of Elymus nutans exhibits a rising trend under future climatic scenario. The main environmental factors limiting the distribution of Elymus nutans include three temperature-related factors: annual mean temperature (-4.2 to 5.0 ℃), maximum temperature of the warmest month (12.3-21.4 ℃), and isothermality (36.4%-52.8%); one precipitation-related factor: precipitation of the driest month (0.6-5.9 mm); one topographical factor: elevation (2830-4839 m); and a human activity factor: anthropogenic disturbance index (1.3-20.6). Under future climate change scenarios, the highly suitable area of Elymus nutans will expand greatly, while the expansion area will remain relatively stable under various emission scenarios. The moderately suitable area of Elymus nutans would not change greatly. The area of lowly suitable zones exhibits different change patterns across different periods, decreasing first and then increasing from 2021 to 2040, but increasing first and then decreasing from 2041 to 2060. Additionally, its centroid will follow a southwestward shift first and a northeastward migration after that. Our results suggest that climate change drives the distribution of Elymus nutans. By elucidating the distribution patterns and the underlying drivers, this study can enhance our ability to protect and utilize Elymus nutans more effectively. Our finding serves as a valuable theoretical basis for endeavors such as ecological restoration, the selection of seed field locations, forage cultivation, and resource conservation.

Key words: MaxEnt model, Elymus nutans, climate change, potential distribution, driving factor