C:N:P stoichiometry of Artemisia species and close relatives across northern China: unraveling effects of climate, soil and taxonomy

Yang YJ, Huang ZY* et al. 2015.

C、N和P的化学计量特征影响着多种生态过程,在生态系统结构和功能中发挥重要作用。然而,目前大多数研究仅关注系统发育关系较远的植物间叶片的化学计量特征。文章提出两个假设:(1)因为区域尺度上非生物环境具有一定的地理格局,系统发育关系较近的植物化学计量特征也应具有一定的地理格局;(2)这些系统发育关系较近的植物在吸收和利用不同元素上具有内在差异,因而它们的化学计量特征仍会在种间表现出强烈的变异。为了验证这些假设,我们从中国北方65个地点采集了48种蒿属植物,分析了其C:N:P的化学计量特征。分析结果表明,元素含量与化学计量特征与经纬度没有相关性,但表现出明显的海拔趋势。气候因子对植物C含量有显著影响,但对其它元素含量和化学计量特征无显著影响。土壤化学特征对C和P含量、C:P和N:P有显著影响。嵌套模型分析结果表明,植物种类解释了所有元素和化学计量特征中>30%的变异,并且不同植物对环境梯度的响应有差异。 这一研究的结果表明,即使是系统发育关系较近的植物,其化学计量特征仍然具有强烈的种间变异。在全球变化的背景下,生态学家在尺度扩展时应当注意不能以某一种植物的化学计量特征代表整个类群。

Carbon (C), nitrogen (N) and phosphorus (P) stoichiometries play critical roles in the function and structure of ecosystems by affecting important ecological processes. Yet, most studies to date have concentrated on foliar stoichiometry of phylogenetically distantly related species. Here, we hypothesized that (1) plant stoichiometry of closely related species still shows biogeographic patterns because of the geographic patterns of abiotic environment at the regional scale and (2) that even related species still differ strongly in their stoichiometry owing to inherent differences in the absorption and retention of different elements. To test the hypotheses, we analyzed the C:N:P stoichiometry of 48 species of Artemisia and its close relatives from 65 sites across northern China. Elemental concentrations and stoichiometry had no correlation with latitude or longitude but showed clear altitudinal trends. Climate had a weak effect on plant elemental concentrations and stoichiometry but not on C concentration. Soil chemistry had significant effects on C and P concentrations, C:P and N:P. Nested models revealed that species identity accounted for more than 30% of the total variance of all elemental concentrations and stoichiometric ratios, and different species responded differently to environmental gradients. Synthesis. Our results highlight that even closely related species can vary importantly in plant element stoichiometry. This suggests that ecologists and global change researchers should be careful not to simply take a species’ stoichiometry as representative of an entire taxonomic group for upscaling of plant chemical responses to climatic and edaphic variation in our fast changing world.