Leaf nitrogen:phosphorus stoichiometry across Chinese grassland biomes
Leaf nitrogen:phosphorus stoichiometry across Chinese grassland biomes
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DOI：
10.1007/s00442-007-0912-y
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发表时间：
2008-03-01
期刊：
影响因子：
2.7
通讯作者：
Fang, Jingyun
中科院分区：
文献类型：
--
作者：
He, Jin-Sheng;Wang, Liang;Fang, Jingyun
叶片N和P的化学计量学与植物生物学的许多方面相关，但在生物地理尺度上这一特征的驱动因素仍然不确定。最近，我们在对中国草原生物群落199个研究点的213种植物进行系统调查的基础上，报道了叶片C和N的分布规律。通过对叶片P的扩展分析，报道了叶片P和N/P比值的模式，并分析了气候变量和系统发育在叶片N：P化学计量学结构模式中的相对贡献。叶磷和N：P比值的平均值分别为1.9mgg(-1)和15.3mgg(-1)，与先前观察到的中国植物区系N：P比值高于全球平均值(约13.8)的结果一致。气候变量与叶P和N：P比值的直接相关性很小，生长季降水和温度共同解释的变化不到2%，而站内差异和系统发育变化解释了叶P和N：P比值总变异的55%和26%。在所有地点和物种中，叶片N和P在所有水平上都呈高度正相关。而叶片N、P在立地内、种内的协变弱于立地和种间。叶片N、P关系受景观尺度的立地间变异(解释58%)和局部尺度的立地内变异(解释24%)共同驱动，而气候因素的影响有限(解释不到3%)。此外，嵩草属和针茅属两个优势属的叶片N/P比对降水的响应也不同。这项研究表明，在生物群水平上，草地叶片化学计量比的主要决定因素是地理变异和种间变异，而不是气候变化。
Leaf N and P stoichiometry covaries with many aspects of plant biology, yet the drivers of this trait at biogeographic scales remain uncertain. Recently we reported the patterns of leaf C and N based on systematic census of 213 species over 199 research sites in the grassland biomes of China. With the expanded analysis of leaf P, here we report patterns of leaf P and N:P ratios, and analyze the relative contribution of climatic variables and phylogeny in structuring patterns of leaf N:P stoichiometry. Average values of leaf P and N:P ratio were 1.9 mg g(-1) and 15.3 (mass ratio), respectively, consistent with the previous observation of a higher N:P ratio in China's flora than the global averages (ca. 13.8), resulting from a lower leaf P. Climatic variables had very little direct correlation with leaf P and N:P ratios, with growing season precipitation and temperature together explaining less than 2% of the variation, while inter-site differences and within-site phylogenetic variation explained 55 and 26% of the total variation in leaf P and N:P ratios. Across all sites and species, leaf N and P were highly positively correlated at all levels. However, the within-site, within-species covariations of leaf N and P were weaker than those across sites and across species. Leaf N and P relationships are driven by both variation between sites at the landscape scale (explaining 58% of the variance) and within sites at the local scale (explaining 24%), while the climatic factors exerted limited influence (explaining less than 3%). In addition, leaf N:P ratios in two dominant genera Kobresia and Stipa had different responses to precipitation. This study suggests that geographic variation and between-species variation, rather than climatic variation, are the major determinants of grassland foliar stoichiometry at the biome level.