Climate-driven shifts in the distribution of the rare earth element hyperaccumulator fern Blechnopsis orientalis: Implications for phytomining and conservation strategies in China

Rising global temperatures are altering species distributions, yet the long-term dynamics of pteridophytes remain poorly documented. Here, we project the potential habitat dynamics of Blechnopsis orientalis, a fern with exceptional rare earth element (REE) accumulation capacity and promising applications in green phytomining, across China under both contemporary and future climate scenarios. Using 646 valid occurrence records and ten comprehensively selected environmental predictors, we applied a parameter-optimized MaxEnt model (RM = 1, FC = QHPT, AUC = 0.947) to evaluate habitat suitability. For future trend simulation, four representative CMIP6 scenarios (SSP126, SSP245, SSP370, and SSP585) were selected, and predictions were analyzed for three time slices (2050s, 2070s, and 2090s). Our principal findings are: (1) Bio9 (Mean Temperature of Driest Quarter) and Bio12 (Annual Precipitation) are the primary drivers of the species' distribution, with a cumulative contribution of 86.7%, confirming temperature and water availability as core limiting factors. (2) Contrary to the widely observed range contraction in most rare plants, B. orientalis exhibits a significant net expansion under all climate scenarios, with the maximum projected expansion area reaching 59.64 × 104 km2, while the contracted area remains below 0.83 × 104 km2. (3) The centroid of suitable habitat shifts generally northwestward, with displacement distances increasing with scenario severity and reaching up to 108.75 km under SSP585-2090s. These findings indicate that B. orientalis possesses strong adaptive capacity to climate warming, and its rare-earth hyperaccumulation function may impose additional constraints on its climatic niche through a transpiration-dependent mechanism. Based on these comprehensive results, we propose three systematic conservation and development schemes: (i) prioritizing the interconnected provincial border zones in southwestern South China as core functional areas for in situ conservation of wild populations; (ii) developing the inland interprovincial junction zone in eastern South China into an official pilot site for the application and dissemination of rare-earth phytomining technology; and (iii) establishing specialized germplasm preservation bases along the axis of the population centroid shift.