Study on succession and mechanism of suitable area of high coverage grassland in Sichuan Basin under climate change

The Sichuan Basin is an important part of the national ecological barrier zone of the Qinghai-Tibet Plateau, and its high-cover grassland is an important natural resource for the survival and development of human beings. The study of succession and mechanisms under climate change conditions can help to rationally develop and utilise grassland resources, carry out conservation and restoration work, and improve the function and stability of grassland ecosystems.In this study, we obtained the distribution data of high-cover grassland in the Sichuan Basin based on the remote sensing monitoring data of land use in China over a period of time, selected 33 environmental variables related to climate, topography and soil, and used the Maximum Entropy Model (MaxEnt) to evaluate the ecological suitability of high-cover grassland in the Sichuan Basin under the modern and future climatic conditions. The results showed that: (1) the area of high-cover grassland suitability in the Sichuan Basin grass ploughing resource area is about 52.06×10⁴ km², and the middle and high suitability areas are mainly distributed in the northern part of Hanzhong Basin. (2) Monthly mean diurnal temperature difference, precipitation in the warmest season, minimum temperature in the coldest month, and seasonal variation of precipitation are the main ecological factors, with contribution rates of 34.0%, 21.8%, 14.1%, and 13.5%, respectively. (3) Suitable zones will increase in the future under different climatic scenarios, and the distribution pattern is more in line with the overall performance in the historical period. The new suitable areas were distributed in the south and north of Hanzhong Basin, while the retained and lost suitable areas were mainly concentrated in the north of Hanzhong Basin. 2050s-SSP2-4.5 scenario had the largest area of potential suitable areas, which indicated that the medium emission reduction pathway was more favourable for the development of high-cover grassland.