The Impact of Climate Change on Chorthippus dubius (Zubovski, 1898) Distribution in Alpine Grassland—A Case Study in the Qilian Mountain National Park, China

Alpine grassland is extremely sensitive to climate change and external interference, and it does not easily recover once damaged. Grasshopper outbreaks pose a serious threat to grassland ecosystem health and to the sustainable development of animal husbandry. However, most of the current grasshopper hazard studies focus on tropical, temperate, and desert areas, and there is still a lack of understanding of the spatial and temporal variation in the Qinghai–Tibet Plateau. Hence, the alpine grassland in the Qilian National Park (located in the eastern Qinghai–Tibet Plateau) was selected as the study area to investigate the primary environmental drivers, construct optimal ecological niche models, and evaluate the impact of climate change on the inhabitable areas of the dominant species Chorthippus dubius (Zubovski, 1898), abbreviated as C. dubius. The results indicate that (1) temperature seasonality, slope, and precipitation were the main influence factors for the distribution of C. dubius; (2) among the 10 ecological niche models, the random forest (RF) model exhibited the highest performance, achieving kappa, TSS, and ROC values of 0.86, 0.90, and 0.98, respectively; and (3) in the future climate scenario (SSP126–SSP585), most of the lower presence probability area (less than 20%) will be transformed into other types, affecting 93.17% of its current area. In addition, the presence probability increased from northwest to southeast gradually. This study clarified the spatial and temporal variation in C. dubius presence probability and its response to climate change, providing a scientific basis for grasshopper control and grassland management in Qilian Mountain National Park.