中文摘要：

我们通过采集中国东部南北样带（NSTEC）上112个样点的102种植物叶片样品，分析了植物叶片氮浓度对植被功能型（PFTs）以及环境因素的响应特征。研究结果表明：（1）植物叶片氮浓度均值为17．7mg.g^-1，最大值和最小值分别出现在落叶阔叶植物和常绿针叶植物中。对乔木而言，叶片氮浓度表现为落叶植物〉常绿植物，阔叶植物〉针叶植物；乔木和灌木的叶片氮浓度显著高于草本植物，而乔木和灌木之间则无显著差异。（2）叶片氮浓度与年均温度（MAT）呈现凸型二次曲线关系，与年均降水量（MAP）则呈现显著的线性负相关关系，与土壤氮素浓度（Nsoil）则线性正相关，并且这种关系并不随着植被功能型的改变而改变。（3）PFTs，气候和Nsoil共同解释植物叶片氮浓度空间格局变异的46．1％，其中PFTs，气候和Nsoil可分别独立解释植物叶片氮浓度空间格局变异的15．6％，2．3％，4．7％。该研究结果表明，气候和土壤氮素对植物叶片氮浓度的影响主要是通过作用于生态系统中的物种组成，而非直接作用实现的。这种基于较大区域尺度上的野外观测分析有助于我们准确的理解植被功能型和环境因素对叶片氮浓度变异的影响机制。

英文摘要：

We conducted a systematic census of leaf N for 102 plant species at 112 research sites along the North-South Transect of Eastern China （NSTEC） following the same protocol, to explore how plant functional types （PFTs） and environmental factors affect the spatial pattern of leaf N. The results showed that mean leaf N was 17.7 mg g^-1 for all plant species. The highest and lowest leaf N were found in deciduous-broadleaf and evergreen-conifer species, respectively, and the ranking of leaf N from high to low was： deciduous 〉 evergreen species, broadleaf 〉 coniferous species, shrubs ≈ trees 〉 grasses. For all data pooled, leaf N showed a convex quadratic response to mean annual temperature （MAT）, and a negative linear relationship with mean annual precipitation （MAP）, but a positive linear relationship with soil nitrogen concentration （Nsoil）. These patterns were similar when PFTs were examined individually. Importantly, PFTs, climate and Nsoil, jointly explained 46.1% of the spatial variation in leaf N, of which the independent explanatory powers of PFTs, climate and Nsoil, were 15.6%, 2.3% and 4.7%, respectively. Our findings suggest that leaf N is regulated by climate and Nsoil, mainly via plant species composition. The wide scale empirical relationships developed here are useful for understanding and modeling of the effects of PFTs and environmental factors on leaf N.