摘要:四子柳（Salix tetrasperma Roxb.）为杨柳科柳属为数不多的分布区扩展到热带的物种之一，广泛分布于华南和东南亚地区，但其生境破碎化较为严重。该物种具有较高的园林绿化价值和生态价值，预测不同气候情景下该物种的地理分布将为四子柳的资源开发和合理利用乃至柳属的起源和分化研究提供重要的科学依据。利用四子柳全面且精确的分布信息和高分辨率环境数据，基于Maxent模型和ArcGIS空间分析，构建其末次间冰期、末次盛冰期、当代以及未来（2050，2070）的潜在空间分布格局，评价环境因子对分布模型的重要性，定量确定未来受到威胁的适宜生境区域和面积。结果表明，四子柳目前的适宜生境面积为234.65×10⁴ km²，主要位于东亚、南亚和东南亚的热带地区，气温年较差和年均降水量是限制其分布的主要环境因子。总体而言，从冰期至未来，四子柳的分布中心有南北往返迁移的趋势。四子柳在末次盛冰期时向西北方向扩张并开始出现于热带地区，表明该物种开始适应热带气候，进入全新世中期以后种群收缩并退缩到云贵高原的河谷地区和印度尼西亚的平原区域。随着全球气候变暖，在不同二氧化碳浓度路径下2050年和2070年四子柳的潜在适生境有可能破碎化增加，建议对缅甸东部及中部成片减少的边缘群体进行实时监测。



Abstract:Salix tetrasperma Roxb. is one of the few species of the genus Salix L. and family Salicaceae with a distribution area extending to the tropical zone. This species has a high landscaping and ecological value, and is distributed widely in south China and southeast Asia, but its habitat is highly fragmented. A prediction of the impact of climate change on the distribution of this species will facilitate the rational utilization of germplasm resources of S. tetrasperma, as well as research into the biodiversity of Salix. Based on comprehensive and accurate distribution records and high-resolution environmental data, we modeled the potential range of S. tetrasperma during the Last Inter Glacial (LIG), Last Glacial Maximum (LGM), current, and future (2050, 2070) periods. We evaluated the importance of environmental factors in shaping the species' distribution, and quantificationally identified regions of high risk under different climate scenarios. The niche models showed that S. tetrasperma has suitable habitat of approximately 234.65×10⁴ km² in the tropical habitats of east Asia, south Asia, and southeast Asia. Air temperature annual range and annual precipitation were identified as the critical factors shaping habitat availability for S. tetrasperma. During the LGM, the distribution center of S. tetrasperma from the glacial epoch to future presented a tendency for migration back and forth between the north and south. The distribution area of S. tetrasperma expanded to the northwest and started to occur in the tropical zone, which suggested it began to adapt to a tropical climate. Populations of S. tetrasperma retreated into the valley of the Yunnan-Guizhou Plateau and plains region of Indonesia after the mid-Holocene period. The habitat of S. tetrasperma might be more fragmented in 2050 and 2070 owing to global warming. We therefore suggest monitoring the peripheral population in eastern and central Myanmar.





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