Abstract
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.