Habitat pattern of Quercus variabilis in China under the background of climate change

To clarify the distribution pattern of Quercus variabilis under the combined influences of climate change and habitat fragmentation, we used 87 occurrence records and 9 climatic variables, and applied the MaxEnt model and ArcGIS to simulate the current and future suitable habitats of Q. variabilis across China under SSP126 and SSP585 scenarios. The results showed that the MaxEnt model performed well (area of receiver operating characteristic curve was 0.884). The main climatic factors influencing the distribution of Q. variabilis were the minimum temperature of the coldest month, precipitation of the wettest quarter, maximum temperature of the warmest month, and mean temperature of the wettest quarter. During 1970-2000, the area of highly suitable habitats for Q. variabilis was approximately 104.92×10⁴ km², mainly located in central, eastern, southwestern, and southeastern China. Under both SSP126 and SSP585 scenarios, the total suitable habitat expanded during 2021-2100, but its structure shifted. The highly suitable area declined significantly (by 44.8%-50.5%), moderately suitable habitat also contracted (by 1.7%-34.4%) except for a slight increase under SSP126 during 2021-2040, and poorly suitable area increased (by 41.7%-104.5%). This trend suggested the increases in fragmentation and the decline of overall suitability of Q. variabilis habitats. The findings would provide scientific guidance for region-specific management and the long-term sustainable utilization of Q. variabilis resources.