Projecting the impacts of climate change on Chinese wetlands using Phragmites australis as an indicator

Wetlands are climate-sensitive ecosystems, yet the future distribution patterns of wetland plants across China under different climate scenarios remain poorly understood, hindering the development of proactive conservation and restoration strategies. In this study, we address this gap by using the widely distributed foundational species Phragmites australis as an indicator to project climate-driven shifts in wetland ecosystems. This study employed 627 occurrence records of P. australis alongside 18 environmental variables covering climate, topography, soil, land use, and human footprint. Using the ENMeval package, we optimized a MaxEnt model to project the species' potential distribution under current conditions and across three future periods (2050s, 2070s, 2090s) under the SSP126, SSP370, and SSP585 scenarios. The objectives were to determine the key environmental drivers of its distribution and to evaluate associated spatial restructuring risks for China's wetland ecosystems in a changing climate. The results show that the MaxEnt model with a regularization multiplier (RM) of 3 and a feature combination (FC) of LQPHT performed with high consistency and accuracy. The dominant environmental factors and their thresholds were: human footprint ≥14.31, elevation ≤2256.88 m, temperature annual range (bio7) ≥ 17.25 °C, mean temperature of warmest quarter (bio10) ≥ 13.75 °C, and mean diurnal temperature range (bio2) ≤ 14.11 °C. The most suitable land use types included paddy fields, dry farmland, other forest land, rivers and canals, lakes, reservoirs and ponds, urban land, rural settlements, other construction land, and saline-alkali land. Under current climatic conditions, suitable distribution for P. australis in China is mainly distributed across North China, Northeast China, Northwest China, and South China. The areas of high and low-suitability distribution is 139.93 × 10 4 km 2 and 380.78 × 10 4 km 2 , respectively. Under future climate scenarios, both high- and low-suitability distribution is projected to decrease to varying degrees, with increased fragmentation. The suitable distribution centroids are expected to shift northwestward. The findings of this study provide a quantitative scientific basis for implementing climate-adaptive wetland conservation and restoration strategies, particularly for optimizing the national ecological conservation spatial layout and establishing early-warning mechanisms.