Aims

为了研究中国陆地植物细根碳(C)、氮(N)、磷(P)的空间变化模式,揭示细根在"温度-植物生理假说"及"生长速率假说"等方面的规律,该文收集已发表的有关中国陆地植物细根研究的文献,从中提取细根C、N、P元素含量及其相关数据,分析了细根C、N、P含量及其比例与经纬度之间的关系。结果表明:细根N、P元素含量均随纬度增加而增加,P含量随经度增加而降低,N:P随经度增加而增加。细根N、P含量与年平均气温、年降水量均呈负相关关系,与土壤养分呈正相关关系。在土壤养分、温度、降水量3个非生物因素中,土壤养分对细根N、P含量的影响最大。该文中细根和粗根的C:P、N:P差异变化不完全支持"生长速率假说"。根系和叶片一样,N、P含量与纬度呈正相关关系,支持"温度-植物生理假说",反映了植物对自然环境的适应策略。

Spatial changes and influencing factors of fine root carbon,nitrogen and phosphorus stoichiometry of plants in China

Aims Fine roots and leaves are important below- and above-ground functional organs. It is widely recognized that leaf nitrogen (N) and phosphorus (P) stoichiometry displays significant latitudinal variations, and two competing theories (i.e. Temperature-Plant Physiological Hypothesis and Growth Rate Hypothesis) have been proposed to explain this phenomenon. Although considerable efforts have been made to test these theories, comparatively few data have been reported for the plants in China to examine the latitudinal and longitudinal variations in fine root carbon (C), N and P stoichiometry. Accordingly, we compiled an extensive data set of root C, N and P stoichiometry, our objective was to address three main issues: (1) whether the C, N and P stoichiometric latitudinal patterns for roots conform to those reported for leaves, (2) how exactly does root C, N and P stoichiometry changes as a function of longitude, and (3) whether the Temperature-Plant Physiological Hypothesis or Growth Rate Hypothesis can account for the latitudinal patterns observed for fine root stoichiometry. Methods We compiled data on fine root C, N and P contents, climate, and geographic location, and analyzed the correlations among these variables. Important findings The N and P contents were higher in fine roots as opposed to coarse roots. The N and P contents in fine roots increased with increasing latitude. P content in fine roots declined with increasing longitude, whereas the N:P of fine roots increased with increasing longitude. The N and P contents in fine roots were negatively correlated with mean annual temperature and mean annual precipitation, but positively correlated with soil nutrient. Among the three abiotic factors (i.e. soil N and P contents, temperature and precipitation), soil N and P levels had the greatest effect on the N and P contents in fine roots . The variations observed in fine and coarse root C:P and N:P were inconsistent with the Growth Rate Hypothesis, whereas the positive correlations between root N and P contents and latitude were the same as those observed for leaves, which support Temperature-Plant Physiological Hypothesis, reflecting an adaptive strategy to environmental conditions.