Global climate change is reshaping the distribution of suitable habitats for plant survival, with particularly severe implications for endangered plant species. Therefore, assessing the impact of climate on these species is essential for safeguarding their persistence in appropriate habitats. This study employed a Maximum Entropy model to systematically evaluate changes in the distribution of Disanthus cercidifolius subsp. longipes under current and future climate conditions. The key environmental factors determining the suitable habitats of D. cercidifolius subsp. longipes are soil water content, minimum temperature of the coldest month, and precipitation of the driest month. Currently, the optimal habitats are largely concentrated in southern China, including Hunan and Jiangxi Provinces. Compared with the current period, the suitable habitat area in most future periods contracts under all three climate scenarios, exceeding the present level only during 2021–2040 under SSP126 and 2061–2080 under the SSP585 scenario. The distribution centroid shifts northeastward under the SSP126, SSP245 and SSP585 scenarios. Niche overlap analysis further indicates that while substantial shifts in suitable habitat will occur, the overall migration range remains limited. These findings highlight that the distribution of D. cercidifolius subsp. longipes is jointly constrained by moisture availability and low-temperature tolerance, as represented by soil water content, precipitation of the driest month, and minimum temperature of the coldest month, as well as the complexity and potential risks in its response to future climate change. This study underscores the need for conservation strategies to address the dual constraints of water and temperature and to develop adaptive measures against potential future contractions in suitable habitat areas.

Climate change can alter the potential distribution patterns of species, and the responses of medicinal plants to environmental change are directly relevant to resource conservation and the planning of suitable cultivation regions. Using the MaxEnt model, we combined occurrence records of four Alisma species (Alisma canaliculatum, A. gramineum, A. orientale, and A. plantago-aquatica) with climatic, topographic, edaphic, and human-activity variables to predict their potential suitable habitats under current conditions and two future periods (2041–2060 and 2081–2100) under three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5). Two hypotheses were tested: (1) species with narrower thermal niches exhibit greater sensitivity to climate change; and (2) closely related species show significant divergence in dominant environmental factors and spatial responses. All models demonstrated good predictive performance (AUC > 0.9). Dominant environmental factors differed markedly among species: A. canaliculatum and A. orientale were primarily constrained by temperature-related variables, whereas A. gramineum and A. plantago-aquatica were more strongly associated with human activity intensity and precipitation-related variables. Consistent with the hypotheses, the potential suitable habitat of A. orientale was projected to change most strongly, while that of A. gramineum remained the most stable. Under the high-emission scenario, the potential suitable habitat of A. canaliculatum was projected to shift northward, accompanied by an increase in total suitable area. A. orientale and A. plantago-aquatica exhibited internal habitat reorganization, characterized by contraction of low-suitability areas and expansion of high-suitability areas. These findings clarify the niche differentiation patterns of closely related species and identify regions where habitat suitability may be retained, lost, or gained, thereby providing a scientific basis for the adaptive management and conservation planning of these medicinal plants under future climate change.