Abstract:

Based on CMIP6 climate model data and the MaxEnt model, this study systematically evaluates the evolution of suitable cultivation areas for single-cropping rice in the Jianghuai region during the climatic baseline period (1985-2014) and the future (2026-2100) under different scenarios, by coupling environmental factors such as soil, topography, and human activities. The results are as follows. (1) Through the “dual-index” mechanism combining collinearity testing and Jackknife method, 9 dominant factors were screened from 14 potential environmental factors, with a cumulative contribution rate of 94.4%. Model validation shows that the prediction accuracy of the optimized MaxEnt model was significantly improved (AUC=0.923), which is superior to the prediction accuracy reported in similar studies (e.g., 0.85-0.90). (2) The mean temperature during the entire growth period of single-cropping rice in the Jianghuai region shows a significant upward trend in the future, with the maximum warming rate under the SSP5-8.5 scenario (0.50℃/(10 a)). Precipitation generally shows an increasing trend, which is higher in the central and northern Jianghuai region than that in the south. (3) During the climatic baseline period, high-suitability areas are concentrated in the Yangtze River Delta and along-river plains, accounting for 21.7% of the total area, characterized by high proportion of paddy soil and superior hydrothermal conditions; medium-suitability areas are mainly located in the plains south of the Huaihe river, accounting for 26.2%; low-suitability areas are distributed in the Huaibei plain, accounting for 35.1%; non-suitability areas include the Dabie mountains and southern Anhui mountains, northwestern drylands, and urbanized areas, accounting for 17.1%. (4) In the future, the suitable areas show a trend of “eastern contraction and northern expansion”. In future periods, under the SSP5-8.5 scenario, the area of high-suitability areas will decrease by 3.8 percentage points, and that of low-suitability areas will increase by 6.6 percentage points. This evolution is mainly driven by the “double-edged sword” effect of climate warming: on one hand, northern Anhui (north of 32°N) becomes the main expansion area due to the increase of ≥10℃ accumulated temperature by 300-450℃·d and the extension of the growth period by 12-18 days; on the other hand, southern Jiangsu (south of 32°N) shows significant contraction under the stress of increased high-temperature days to 35-45 days, especially the probability of extreme high temperature during the critical growth stages (booting-heading stage) of rice increases by a factor of 3-5. It is proposed to enhance climate resilience through the breeding heat-tolerant varieties and optimizing planting layouts, providing a scientific basis for formulating regional agricultural adaptation strategies.

Key words: Single-cropping rice in the Jianghuai region, Suitable habitat, Climate change projection, MaxEnt model