中文摘要：

森林生态系统是陆地生态系统最重要的碳库和碳汇,其地下-地上生物量分配规律即根冠比（R/S）,对于精确估算森林生物量,尤其是对建造森林地下生物量估算模型具有重大参考意义.为探究大尺度上气候、林分因子对中国天然林根冠比的影响,对1 109块天然林样地进行统计分析.结果显示：中国天然林R/S平均值为0.26,阔叶森林的R/S要显著高于针叶森林,落叶森林的R/S要显著高于常绿森林,年均温、林龄及水分可利用性与中国天然林R/S呈显著负相关关系,年均温是影响中国天然林R/S变化的最主要因子.综合纬度、经度、年均温、降水、林龄等环境因素的影响发现,纬度、林分密度是影响R/S的最主要因素.因此,精确估算森林碳储量和森林生物量分配时必须考虑纬度和林分密度的影响.

英文摘要：

Forest ecosystems play an important role in global carbon cycle. Accurate understanding of below- and aboveground biomass allocation pattern（i.e. the root-shoot ratio, R/S） and its infl uencing factors would help to better characterize the regional and global carbon sink, stock and cycle of forest ecosystems. The purpose of this paper was to investigate the effects of climatic and stand factors on the root–shoot ratio of China＇s natural forests at a large scale. We classified all data of 1109 sample plots into 17 types of forest and calculated the R/S [root biomass /（stem ＋ branch ＋ leaf biomass）] of the forest communities. Because precipitation could not completely refl ect the forest water conditions, the ratio of mean annual precipitation to potential evaporation was used to evaluate the impact of water availability on the R/S. Finally, latitude, longitude, temperature, water availability, stand density and stand age were selected to analyze their effects on the R/S using multiple linear regression. Our results showed the mean value of R/S in China＇s natural forests as 0.26. The R/S of deciduous forests was significantly higher than that of evergreen forests, and the R/S of broadleaved forests was higher than that of conifer forests. Furthermore, R/S of China＇s natural forests was significantly and negatively correlated with the stand age and water availability. The major infl uencing factors for the R/S of China＇s nature forests were latitude and stand density. The results suggested that we should include in consideration temperature and stand density in calculation of forest carbon stock and forest biomass allocation.