云南生物多样性分布格局的梯度分析

Gradient Analysis on Biodiversity Spatial Distribution Pattern in Yunnan Province,China

从北到南选择7个具有代表性的保护地构建纬向梯度研究样带,自西向东同样选择7个具有代表性的保护地构建经向梯度研究样带,通过计算β多样性指数等方法对云南生物多样性空间分布格局进行分析;以云南129个县级行政单位为样方,以各县的物种总数、垂直层谱数等17个代表生物多样性的变量为自变量,以经纬度、海拔等21个地理环境和生物环境因子为因变量,在CANOCO 4.5软件支持下,进行了排序分析。结果表明:(1)云南生物多样性分布格局的纬度和经度地带性均不十分显著,其动植物的空间分布格局由不同环境变量共同决定;(2)但在各类生物多样性分布格局的影响因素中,海拔高差、叶面积指数、湿润指数、最高海拔、最低海拔、平均降水量、经度、最冷月NDVI为生物多样性最具决定意义的主变量,其他变量为协变量;(3)研究发现经度对生物多样性的决定性作用比纬度更加显著,是通过蒙特卡洛检验具有显著意义的一个环境梯度。相关研究结果对云南生物多样性保护工作具有一定的指导意义。

Seven representative protected areas were selected as plots to form a spectrum along the latitudinal envi- ronmental gradient of Yunnan Province, China. Meanwhile, same number of protected areas was selected along the longitude environmental gradient. Based on species richness of the 14 plots, seven different β diversity indices were calculated to reveal the spatial pattern of Yunnan＇ s biodiversity distribution. Using the CANOCO 4.5 soft- ware, ordation （gradient analysis） of Yunnan＇ s species diversity and environmental were carried out, in which Yunan＇s 129 counties were used as study plots; 17 biodiversity factors, e.g. county level species numbers and vertical stratification layers of plant communities, were used as independent variables; and 21 geographical and en- vironmental factors besides latitude, longitude and altitude were used as dependent variables. Result showed that, 1 ） neither the longitude nor the latitude environmental gradient has been decisive for the spatial pattern of Yunnan＇ sspecies biodiversity. 2） Among the multitude driving factors of biodiversity distribution the most decisive ones are respectively ： the relative height difference, the leaf area index, the humidity index, the maximum and minimum el- evations, multi-year average precipitation, the longitude, and Normalized Difference Vegetation Index of the coldest month in descending order. They were the master variables, and all other variables are just concomitant variables. 3 ） unexpectedly, the longitude environmental gradient was more powerful than latitude in explaining Yunnan＇ s biodiversity distribution pattern. It was among top eight influential factors that passed the Monte Carlo test. The founding may provide useful guidance for biodiversity conservation works of Yunnan in the future.