【目的】研究影响杜鹃花科植物照山白(Rhododendron micranthum)分布的主要环境变量及未来气候变化情景下照山白在中国的潜在地理分布,为冬季缺绿城市景观的提升提供资源,也为物种的保护和管理提供科学依据。【方法】以照山白为研究对象,运用R语言kuenm软件包优化的MaxEnt模型和ArcGIS软件,基于182条照山白分布点数据和18个环境变量进行潜在适生区预测,研究影响其地理分布的主要环境变量,同时预测其在3种温室气体排放路径下即2030s(2021—2040年)、2050s(2041—2060年)和2070s(2061—2080年)潜在适生区的空间分布格局和质心变化趋势。【结果】①最优模型参数正则化乘数调控倍频RM为2.9、特征组分FC为LQPTH时,模型预测AUC值最高(0.973 2±0.007 1);②影响照山白适生区分布主要环境变量及阈值为最冷月最低温(-13.48~1.02 ℃),最热季降水量(270.12~404.76 mm),环境变量在阈值范围内,照山白表现出一定的适生性;③当前气候条件下,照山白高、中、低适生区面积分别为43.83×10⁴、43.79×10⁴和62.01×10⁴ km²,主要分布在北京、甘肃、陕西、河北、山东、山西、河南、辽宁和四川,其中,北京的平均适生指数最高(0.801 5);④未来气候条件下,温室气体排放强度越大,照山白总适生区越小,表明全球气候变暖不利于照山白的生长,同时,SSP126(低强迫情景)情景下,物种分布质心向低纬度迁移;SSP585(高强迫情景)情景下,质心向高纬度迁移。【结论】利用MaxEnt模型进行照山白不同时期潜在分布预测结果可靠,在未来气候情景下,照山白在中国适生区的破碎化程度均加重,低温室气体浓度排放下的气候条件有利于照山白植物的生长,高温室气体浓度排放下的气候条件使得照山白适生区面积减少。

【Objective】This study is dedicated to explore the key environmental variables affecting the distribution of Rhododendron micranthum and predicting its potential geographical distribution under future climate change scenarios in China. The findings aim to support urban greening strategies for winter vegetation-deficient cities and provide scientific guidance for species conservation and management of R. micranthum.【Method】R. micranthum was taken as the research object. Based on 182 distribution points and 34 environmental factors, the MaxEnt model and ArcGIS software, optimized by the R language kuenm software package, were utilized to predict the potential suitable areas. The main environmental variables influencing its geographical distribution were analyzed. Additionally, the spatial distribution patterns and centroid change trends of potential suitable areas in the 2030s (2021-2040), 2050s (2041-2060), and 2070s (2061-2080) under three different greenhouse gas emission scenarios were predicted.【Result】(1) When the optimal model parameters are set as RM = 2.9 and FC = LQPTH, the model achieves the highest prediction accuracy (AUC value is 0.973 2 ± 0.007 1).(2) The primary environmental variables and their corresponding thresholds that impact the distribution of suitable areas for R. micranthum are the lowest temperature of the coldest month, ranging from -13.48 ℃ to 1.02 ℃, and the rainfall during the hottest season, varying between 270.12 mm and 404.76 mm. Within the threshold ranges of these environmental variables, R. micranthum demonstrates a certain level of habitability.(3) Under the current climate conditions, the areas with high, medium, and low suitability for R. micranthum are 43.83×10⁴, 43.79×10⁴, and 62.01×10⁴ km², respectively. These areas are predominantly located in regions such as Beijing, Gansu, Shannxi, Hebei, Shandong, Henan, Liaoning, and Sichuan. Among them, Beijing has the highest average suitability index, which is 0.801 5.(4) Under future scenarios, higher emission intensities reduced total suitable areas, indicating global warming may hinder R. micranthum growth. Meanwhile, under the SSP126 (low-forcing scenario), the centroid of the suitable areas migrates towards lower latitudes, while under the SSP585 (high-forcing scenario), it migrates towards higher latitudes.【Conclusion】The analysis using the MaxEnt model yields reliable results for predicting the potential distribution of R. micranthum at different stages. In future climate scenarios, the fragmentation degree of suitable areas for R. micranthum in China is expected to increase. Climate conditions associated with low greenhouse gas concentration emissions are favorable for the growth of R. micranthum, whereas those under high greenhouse gas concentration emissions lead to a reduction in its suitable areas.