中国东黄海海岛5种常见草本的碳氮磷化学计量特征

研究不同纬度海岛共有植物种的碳(C)氮(N)磷(P)化学计量变异特征,有助于剔除植物谱系的影响,揭示植物对海岛环境条件变化的适应策略.本研究以中国东部9个典型海岛的5种常见共有草本植物艾草、狗尾草、葎草、麦冬、酢浆草为研究对象,测定和分析了其地上部分和根系的C、N、P化学计量比,及其与土壤C、N、P含量,温度和降水的关系.结果表明: 9个海岛5种草本地上部分C、N、P含量分别为352.16～518.16、10.81～34.43、0.58～2.38 mg·g^-1,C∶N、N∶P、C∶P分别为11.98～38.99、4.67～27.47、133.39～748.54;根系C、N、P含量分别为312.28～493.34、9.26～23.27、0.40～2.10 mg·g^-1,C∶N、N∶P、C∶P分别为18.18～46.79、8.53～37.38、174.45～1120.40.海岛常见草本的地上部分N、P含量均随着纬度的升高而增高,而N∶P随着纬度的升高而减小;P含量较N含量具有更高的变异性和环境依赖性,气候因子可以解释草本地上部分N、P、N∶P变异的60%;但草本的根系N、P及N∶P不依赖纬度变化而变化,气候因子只解释了根系中的N、P变异的6%～10%.气候因子和土壤养分对植物地上部分及根系的变异贡献率不同,土壤N与P含量对草本植物根系的P含量有显著影响,植物地上部分P含量与土壤P含量呈显著正相关,土壤特性解释了根系N、P变异的37%.研究表明,在剔除植物谱系的影响后,纬度差异导致的环境变化是5种海岛常见草本地上部分的N、P及N∶P变异的主要原因,土壤养分是根系P变异的主要原因.

Carbon,nitrogen and phosphorus stoichiometry of five common herbaceous species across islands in the Yellow Sea and the East China Sea.

Understanding variation of carbon (C), nitrogen (N) and phosphorus (P) stoichiometry in common plant species across islands along a latitude gradient is insightful to reveal the adaptation strategies of plant species to environmental changes. Five common herbaceous species including Artemisia argyi, Setaira viridis, Humulus japonicus, Ophiopog onjaponicus, and Oxalis corniculata were sampled in 125 plots across nine islands in Eastern China. C, N and P contents in leaves, stems, and roots of five plant species were measured, and their relationships with soil C, N and P contents as well as mean annual air temperature (MAT) and mean annual precipitation (MAP) were investigated. The results showed that the range of C, N and P contents in aboveground parts of five species across nine islands was 352.16-518.16, 10.81-34.43, 0.58-2.38 mg·g^-1, while the range of C:N, N:P and C:P was 11.98-38.99, 4.67-27.47, 133.39-748.54, respectively. In terms of roots, the range of C, N and P contents of five species was 312.28-493.34, 9.26-23.27, 0.40-2.10 mg·g^-1, while the range of C:N, N:P and C:P was 18.18-46.79, 8.53-37.38, 174.45-1120.40, respectively. With the increases of latitude, contents of N and P in aboveground parts increased, but N:P decreased. Relative to N content, P content showed higher variation and was largely dependent on environment. Climate factors explained 60% of the variation of N and P contents and N:P across nine islands. In contrast, N and P contents and N:P of roots were independent of latitude, with climatic factors only explained 6%-10% of their variations. The contribution of climatic factors and soil nutrients contributed to the variations of N and P contents differed between above ground parts and roots of five species. Soil N and P had significant effects on P content in roots. Soil P content was positively correlated to aboveground P content. Soil properties explained 37% of the variation in N and P contents of plant roots. Our results suggested that latitude-associated environment shifts were the main drivers of variation in N and P contents and N:P in aboveground parts, and soil nutrients especially affected variation in P in roots of five common plant species, when the effects of plant phylogeny was controlled.