关键词: 桫椤科, MaxEnt模型, 气候变化, 潜在适生区, 长期避难所

Abstract: Climate change is profoundly reshaping the distribution patterns of rare and endangered plants and threatening their persistence. We investigated the impact of climate change on rare and endangered Cyatheaceae plants, including Alsophila spinulosa, A. costularis, and Sphaeropteris brunoniana. We used an optimized MaxEnt model to predict their potential suitable habitat patterns and shifts under the baseline period and future periods (2050 and 2090) across three climate scenarios (SSP126, SSP245, SSP585), and identified priority conservation areas through suitable habitat overlap analysis and long-term stable refugia identification. Results showed reliable model predictions (area under the receiver operating characteristic curve>0.96, true skill statistic>0.81, continuous Boyce index>0.90). Climatic factors were the dominant environmental variables driving the distribution of the three Cyatheaceae species. Compared to the baseline period, the suitable habitat area of A. spinulosa continued to shrink under future climate change, while both A. costularis and S. brunoniana showed general expansion in the mid-term (2050) followed by predominant contraction in the late period (2090), with the most significant changes occurring under the high-emission scenario (SSP585). Under the SSP585 scenario, the suitable habitat area of A. spinulosa continuously shrank from 154.22×10⁴ km² to 97.84×10⁴ km² by 2090. The suitable habitat area of A. cos-tularis first increased from 138.27×10⁴ km² to 154.84×10⁴ km² by 2050, and then declined to 149.44×10⁴ km² by 2090. The suitable habitat area of S. brunoniana first increased from 92.62×10⁴ km² to 220.44×10⁴ km² by 2050, and then declined to 47.68×10⁴ km² by 2090. The overall distribution patterns of potential suitable habitats for the three Cyatheaceae species under three future climate scenarios were similar to those of the baseline period, concentrated in southwestern and southern China, but all exhibited dynamic change. During the baseline period, the centroids of the suitable habitats of A. spinulosa, A. costularis, and S. brunoniana were located in Liuzhou, Guangxi, Qiandongnan Miao and Dong Autonomous Prefecture, Guizhou, and Zunyi, Guizhou, respectively. The centroids of the three Cyatheaceae species showed an overall trend of northward expansion under low-emission scenario and contraction toward cooler regions to avoid heat under high-emission scenario, with migration intensity increasing with rising emission. In terms of migration direction, A. spinulosa migrated southeastward, A. costularis migrated northwestward, and S. brunoniana migrated southwestward. Southwestern Yunnan (Xishuangbanna, Pu'er, Lincang) and Hainan constitute the core refugia, with the highest and most stable overlap of suitable habitats for all three species, yet there are significant conservation gaps currently. In the future, these regions should be designated as priority conservation areas, with strengthened in-situ conservation in their core refugia, complemented by near-natural habitat restoration to enhance landscape connectivity, thereby addressing the long-term challenges posed by climate change.

Key words: Cyatheaceae, MaxEnt model, climate change, potential suitable habitat, long-term refuge