摘要:为阐明黄河三角洲自然保护区生态系统的元素含量水平和化学计量特征并判断该区域植被生长的限制因子，选择保护区5种典型植物群落翅碱蓬、碱蓬、芦苇、柽柳和白茅为研究对象，测定植物不同器官和土壤剖面中有机碳、全氮、全磷含量，分析保护区植物群落与土壤的C、N、P化学计量特征。结果显示：5种群落中典型植物各器官C和P含量规律大体一致，除白茅和柽柳外，均表现为叶 > 根 > 茎，白茅茎的C和P含量高于根。不同植物器官N含量则表现出一致的变化规律，均为叶 > 茎 > 根。各植被类型叶片N：P值均小于12，且与根系的N：P值接近。土壤C、N含量的平均值分别为4.78 g·kg-1、0.32 g·kg-1，均低于全国水平。P含量的平均值为0.53 g·kg-1，略低于全国水平。不同土层之间土壤元素含量差异不显著。不同群落土壤C：N：P值不同，同一群落不同土层的土壤C：N：P值变异性较小。植物叶片C、N、P含量以及C：N、C：P与0~10 cm、10~20 cm、20~40 cm土层土壤C、N含量之间均存在显著的相关关系（P < 0.05）。以上结果表明，黄河三角洲自然保护区不同土层土壤C、N、P含量相对稳定，总体低于全国水平，土壤N的匮乏引起了C：N和C：P值的变化。植物叶片和根系的C：P值接近，说明生态系统元素循环相对稳定，同时叶片N：P值小于12，进一步说明土壤中N的匮乏使其成为植物生长的限制因子。
Abstract:The in-depth understanding of stoichiometry of plant and soil is beneficial for discovering convergence and divergence of ecosystem compositions, and forecasting response of ecosystem to environment change. The Yellow River Delta is an active and younger ecosystem, its' stoichiometry of plant and soil may impact ecosystem structure, function and stability. The aim of this study was to clarify the characteristics of carbon (C), nitrogen (N) and phosphorus (P) contents and stoichiometry of plants and soils in the Natural Reserve of Yellow River Delta. In the study, five vegetation communities from sea to inland were selected, which were Suaeda salsa, S. heteropter, Phragmites communis, Tamarix chinensis and Imperata cylindrical communities, to analyze contents of C, N and P of different organs of plants and soils. The results showed that C and P contents of plant leaf were higher than those of root, and those of stem were lowest for all the vegetation communities, except T. chinensis and I. cylindrica communitis. In I. cylindrica community, C and P contents were higher in plant stem than in root. N content of leaf was higher than of stem and that of root was lowest for all the vegetation communities. N:P ratio of leaf was lower than 12 and was not significantly different from that of root in all ecosystems. The average contents of soil organic C, total N and P were respectively 4.78 g·kg-1, 0.32 g·kg-1 and 0.53 g·kg-1, with all lower than the national average. The differences in contents of soil C, N and P in different soil layers were insignificant. Soil stoichiometry ratio was significantly affected by vegetation type, but the spatial variability was insignificant. There was a significant correlation between contents of leaf organic C, N and P and stoichiometry ratios of C:N and C:P and then the contents of soil C and N in the 0-10 cm, 10-20 cm and 20-40 cm soil layers (P < 0.05). In conclusion, the results showed that the contents of C, N and P were stable in soil profile and lower than the national level. The low content of N affected the variations of C:N and C:P ratios. Consistent with C:P ratio of plant leaf and root, the cycles of the elements were stable in the ecosystem. Then N:P ratio of plant leaf was lower than 12. The findings in this study demonstrated that N was the limiting nutrient element in ecosystems of the Yellow River Delta Natural Reserve.
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