基于中国植被图的西南地区主要乔木物种丰富度格局

Pattern of main tree species richness in Southwest China based on Chinese vegetation map

以中国西南地区(云南、四川、重庆、贵州)为研究区,基于《1∶100万中国植被图》113种乔木分布数据,结合ArcGIS和37个环境变量,筛选各乔木主导环境变量,构建最大熵分布预测模型,进而拟合得到西南地区乔木物种丰富度的空间分布图,并结合未来气候情景预测西南地区乔木物种丰富度变化趋势.结果表明:(1)西南地区乔木物种丰富度整体格局呈现北高南低的分布特点,丰富度热点地区主要分布于25.0°N—30.0°N与100.0°E—105.0°E范围内,即横断山脉地区,其次在滇南与滇东南区域同样具有较高的物种丰富度;丰富度低值区域为川西北以东区域、四川盆地中丘浅区、云贵高原腹地.(2)未来气候情景下,乔木物种丰富度变化整体呈现递减趋势,丰富度高值分布区域下降趋势明显,仅有滇西北、三江流域与贵渝交界之处以南的物种丰富度略有增高.(3)西南地区乔木物种丰富度分布格局受温度和降水的共同影响,最湿季均温与年降水量是决定西南地区乔木物种当前分布格局的主导环境因子.

To acquire knowledge on the richness of tree species in southwest China for the conservation and sustainable development of forests,data on 113 main tree species in 4 southwest provinces of China,Yunnan Province,Guizhou Province,Sichuan Province,and Chongqing City,were extracted from the Vegetation Map of China(scale 1∶1000000).Based on the data,a prediction model,the maximum entropy model was established concerning 37 environmental factors using ArcGIS.Spatial distribution maps on tree species richness were fitted under 3 scenarios to reveal the dynamics of tree species richness in southwest China.The results showed that:(1)the richness of main tree species in southwest China followed an uprising trend from the southern region to the northern part,peaking around the Hengduan Mountain region(25.0°N—30.0°N,100.0°E—105.0°E).The richness of tree species was relatively high in southern and southeastern Yunnan.While the regions with low species richness included the eastern part of northwest Sichuan,the hilly part of Sichuan Basin with moderate altitude,and the hinterland of the Yunnan-Guizhou Plateau.(2)In the future climate scenario,tree species richness decreased,especially in the regions used to be high,except for some upticks in northwest Yunnan,the Three Rivers Basin,and the south of the border-region of Guizhou and Chongqing.(3)Temperature and precipitation jointly affected the distribution pattern of main tree species richness in southwest China.Mean temperature of the wettest season and annual precipitation were the most critical factors determining tree species richness pattern in southwest China.