基于MaxEnt模型的雅砻江冬麻豆生境适宜性评价

Abstract

雅砻江冬麻豆（Salweenia bouffordiana）是近年发现的西南特有冬麻豆属新濒危种，主要分布于四川新龙县的雅砻江河谷。开展其生境适宜性评价及其影响因素分析是对其有效保护的前提和基础。基于2015年8月在雅砻江河谷调查获得的55个分布点，结合24个环境变量数据，利用最大熵模型分析影响雅砻江冬麻豆生境的主要环境因子及其适宜生境预测。结果表明：（1）AUC（曲线下面积）值高于0.9，模型具有较高的准确度，适宜于雅砻江冬麻豆的生境适宜性预测和评估；（2）年均温、最湿月降水、昼夜温差月均值和距河流距离是影响雅砻江冬麻豆生境的最主要环境变量，其最适生境环境变量组合为年均温7.9℃、最湿月降水120-124 mm、昼夜温差月均值13.8℃以及距河流距离33 m；（3）雅砻江冬麻豆的潜在适宜和次适宜生境面积分别约为4.83×10³ hm²和2.37×10⁴ hm²，但仅约7.56×10² hm²的潜在适宜生境和3.28×10³ hm²的潜在次适宜生境位于现有自然保护区管辖范围内。雅砻江冬麻豆的潜在适生区主要沿雅砻江河谷呈狭长的条带状分布，现存区受人类活动影响大，未有生物学地位定级，应尽快确定其生物学保护地位，建立保护小区或社区保护地进行就地保护。;Salweenia bouffordiana is a recently discovered endangered endemic species in southwest China, which mainly distributes along the valley of Yalong River in Xinlong County, Sichuan Province. The effective conservation of S. bouffordiana lies on evaluation of habitat suitability. The MaxEnt model is employed to identify the primary impact factors of the habitat of S. bouffordiana and to predict and evaluate its potentially suitable habitats. The analysis is based on 24 environmental variables of the area and data of field investigation along the Yalong river valley in 55 distribution points. We found that: (1) the AUC (area under ROC curve) value is over 0.9, indicating that the predictive effect of this model is appropriate, and the model can be used to predict and assess the habitat suitability of S. bouffordiana. (2) Mean annual temperature, precipitation of wettest month, mean diurnal temperature range and distance to river are the most predominant environmental variables affecting the habitat suitability of S. bouffordiana. The most suitable combination of environmental variables is a mean annual temperature of 7.9 ℃, a precipitation of wettest month of 120-124 mm, a mean diurnal temperature range of 13.8 ℃ and a distance of 33 m to river. (3) The areas of potential suitable and sub-suitable habitats for S. bouffordiana are 4.83×10³ hm² and 2.37×10⁴ hm², respectively. However, only potential suitable habitats of 7.56×10² hm² and sub-suitable habitats of 3.28×10³ hm² are within the jurisdiction of the existing nature reserves. The potential habitats are limited and mainly distributed along the valley. There are existing human activities to hamper the development and propagation of the population of S. bouffordiana in the current survival areas. In addition, the biological status of S. bouffordiana has not yet been assessed and determined. We suggest that the assessment and determination of biological status for S. bouffordiana should be put on the agenda. Small nature protected areas or community protected areas should be introduced for in-site conservation.