中国主要湿地植被氮和磷生态化学计量学特征

研究湿地植物氮(N)和磷(P)的生态化学计量学特征对揭示植物与生境的耦合关系具有重要意义。通过收集中国52个采样区湿地植物不同器官和全株样本的N和P含量, 对其进行分类和统计分析, 探讨植物器官、生长期、植物类型、湿地类型和气候带对湿地植物N和P生态化学计量学特征的影响。结果表明: 1)湿地植物各器官N、P和N:P的几何平均值均表现为叶片(N, 16.07 mg·g^-1; P, 1.85 mg·g^-1; N:P, 8.67) >地上部分(N, 13.54 mg·g^-1; P, 1.72 mg·g^-1; N:P, 7.96) >茎(N, 7.86 mg·g^-1; P, 1.71 mg·g^-1; N:P, 4.58); 2)叶片N含量随时间变化呈现“三峰”型变化, 峰值分别出现在5月、7月和9月; 茎的N含量随时间变化表现为“双峰”型, 峰值出现在5月和9月; 成熟期之前, 植物叶片的N:P与N趋同波动, N:P主要受N含量控制; 衰老期N:P受P含量控制。3)湿地类型是影响植物叶片N和P生态化学计量特征的关键因素, N和P含量最高值出现在河流, 最低值出现在沼泽湿地, N:P的变化趋势大致与之相反。4)植物叶片N、P和N:P的几何平均值都表现为热带>温带>亚热带, 但总体差异不显著(p > 0.05)。5)中国大部分湿地植物叶片N:P < 14, 表现为N限制。

Stoichiometric characteristics of nitrogen and phosphorus in major wetland vegetation of China

Aims Little is known on the stoichiometric characteristics of nitrogen (N) and phosphorus (P) in wetland vegetation across China. This work is aimed to study the stoichiometric characteristics of wetland vegetation in China, which are of great significance for revealing the coupling relationship between vegetation and habitats.
Methods Based on previous studies, a data set comprising N and P contents and N:P of wetland vegetation attained from 649 observations in 52 study sites, was classified and analyzed, which concerned vegetation organs, growth periods, plant life forms, climate zones and wetland types.
Important findings The geometric mean of N, P and the N:P of different organs occurred in descending order as follows: leaf (N, 16.07 mg·g^–1; P, 1.85 mg·g^–1; N:P, 8.67) > aboveground organ (N, 13.54 mg·g^–1; P, 1.72 mg·g^–1; N:P, 7.96) > stem (N, 7.86 mg·g^–1; P, 1.71 mg·g^–1; N:P, 4.58). Leaf N showed a three-peak seasonal distribution, with the peaks occurring in May, July and September, whilst stem N exhibited a bimodal distribution with peaks in May and September. Leaf N:P fluctuated in conformity to N before maturity, but changed corresponding to P in senescence phase. The type of wetlands was found to be the key factor significantly impacted the stoichiometric characteristics of wetland vegetation in China. Specifically, the highest and lowest leaf N and P contents were found in the bottom lands and marshes, respectively, while the N:P displayed a reversed trend. The geometric mean of leaf N, P contents and the N:P followed the order of: tropics > temperate zone > subtropics, albeit no significant differences (p > 0.05) among them. In addition, most of the leaf N:P were less than 14, indicating that the wetland vegetation in China was under the conditions of N limitation.