摘要：
Vitex trifolia var.simplicifolia (Viticis fructus) is not only valuable as a medicinal plant,but also ecologically important.It can function as a wind break,and it stabilizes sand and soil,and it conserves water.Predicting the impact of climate change on the spatial distribution of V.trifolia var.simplicifolia may provide a scientific basis and reference for the sustainable use of this important plant.Using a Maximum Entropy (MaxEnt) model,we simulated the geographical distribution of V.trifolia under the current climatic conditions in China based on species presence data at 126 locations and data for 22 environmental factors.Then,we used the model to predict the future distributions of V.trifolia in two periods (2050s and 2070s) under four different climate change scenarios.The results showed that the MaxEnt model was highly accurate (mean area under ROC curve,0.988).The main climatic factors influencing the geographic distribution of V.trifolia were altitude,mean diurnal air temperature range,precipitation in the coldest quarter,and precipitation in the driest month.The model simulations indicated that,under the four scenarios,V.trifolia will widen its distribution because of a rapid increase in suitable habitat areas and a slow increase in marginally suitable habitat areas.During the period of 2041-2060,the potential distribution area of suitable habitat would increase from the current ratio of 5.03％ to 15.88％,17.00％,17.59％,and 23.11％ under scenarios 1-4,respectively.The potential distribution area of marginally suitable habitat would increase from the current ratio of 8.86％ to 11.09％,10.31％,11.53％,and 12.96％ under scenarios 1-4,respectively.During the period of 2061-2080,the potential distribution area of suitable habitat would increase to 21.22％,22.21％,24.57％,and 30.66％ under scenarios 1-4,respectively,and the potential distribution area of marginally suitable habitat would increase to 11.85％,12.07％,13.99％,and 14.66％ under scenarios 1-4,respectively.In terms of the spatial distribution of the potential habitat area of V.trifolia,both the distributional range and the center of distribution of suitable and marginally suitable habitat areas would shift from coastal areas to inland.The distribution of suitable habitat area in Hunan and Jiangxi provinces would increase rapidly.Especially in Sichuan Province,where there is only a small percentage of marginally suitable habitat area currently,the potential marginally suitable habitat area would increase,and the suitable habitat area would appear and increase rapidly under climate change.%单叶蔓荆为我国常用中药蔓荆子的来源之一,不仅具有良好的药用价值,还具有很高的生态效益,能很好地防风固沙和保持水土.预测气候变化对该物种分布范围的影响可以为单叶蔓荆的可持续利用提供科学基础和参考依据.本研究利用获得的单叶蔓荆126个地理分布记录和22个环境因子,利用MaxEnt模型分析了单叶蔓荆在我国全国范围内的潜在地理分布,并基于该模型预测了4种气候情景下21世纪50和70年代单叶蔓荆分布范围.结果表明,最大熵模型预测单叶蔓荆潜在生境分布的精度较高(接收者操作特征曲线下方的平均面积为0.988),海拔、平均气温日较差、最冷季度降水量和最干月份降水量是影响单叶蔓荆分布的主要气候因子.由模型预测可知,在4种气候情景下,单叶蔓荆在全国适宜生境和低适宜生境的数量均有不同幅度的增加,适宜生境增加较快,低适宜生境增加缓慢;到2050s阶段,适宜生境比例由当前的5.03％分别上升到15.88％、17.00％、17.59％和23.11％;低适宜生境比例由当前的8.86％分别上升到11.09％、10.31％、11.53％和12.96％;到2070s阶段,适宜生境比例分别上升到21.22％、22.21％、24.57％和30.66％;低适宜生境比例分别上升到11.85％、12.07％、13.99％和14.66％.空间分布上,单叶蔓荆的适宜生境和低适宜生境的范围及几何中心都由沿海地区向内陆扩散;湖南和江西两省的适宜生境比例增长较快,尤其在四川境内,当前只有很小比例的低适宜生境,随着气候的变化,低适宜生境面积有所上升,并且适宜生境开始出现且增长速度较快.
