Climate change poses significant challenges to forest biodiversity by altering species distributions. This study employed the MaxEnt model to predict the current and potential future suitable habitats of five Alnus species in China under four Shared Socioeconomic Pathways. Model accuracy was high, with temperature seasonality identified as the most influential variable. In addition, predicted range shifts showed species-specific patterns, with most species expanding toward higher latitudes and elevations. In contrast, Alnus ferdinandi-coburgii exhibited consistent habitat contraction. These findings enhance understanding of the climatic responses of Alnus species and provide a scientific basis for targeted conservation and management strategies under future climate change, and may offer insights into habitat responses of Alnus species in other temperate regions.

Climate change is reshaping the distribution of forest species globally, yet its effects on the temperate tree genus Carpinus in China remain understudied. This study used an ensemble species distribution modeling framework to predict current and future suitable habitats for 32 Carpinus taxa under three shared socioeconomic pathway (SSP) climate scenarios for the 2090s. Five algorithms were integrated, and models with high predictive performance (AUC > 0.9) were used to generate ensemble forecasts. The ensemble models achieved AUC values no lower than 0.987 and TSS values no lower than 0.904. The results showed a clear trend of northwestward and upslope range shifts, with substantial habitat contractions under high-emission scenarios. Temperature seasonality and annual precipitation were identified as key environmental drivers. Two narrowly distributed species, C. omeiensis and C. londoniana var. lanceolata, are projected to lose all suitable habitats under SSP585, indicating a high extinction risk. These findings emphasize the importance of integrating climate-based risk assessments into conservation strategies and highlight the need to prioritize vulnerable species and high-elevation refugia to safeguard the long-term persistence of Carpinus diversity in China.