摘要:探讨湿地植物根系碳（C）、氮（N）浓度及其化学计量关系对于进一步阐明湿地生态系统细根周转及养分循环具有重要意义。基于Pregitzer的根序分级法分析了鄱阳湖南矶湿地22种植物根系全C和全N浓度。结果表明：根系全C、全N浓度及C/N值变化范围分别为：267.15-423.22 mg/g、2.22-31.05 mg/g和2.27-71.78。1-2级根全C、全N及C/N之间具有显著相关性，但与3级根不相关。根系全C和C/N随根序的升高而增加，全N则随根序升高而降低，根系分级在湿地植物C、N化学计量关系研究中十分必要。根序、物种及其交互作用均显著影响研究区植物根系的全C、全N浓度及C/N计量关系。根系C/N化学计量关系在不同生境间未发生显著变化，表明群落尺度下的C/N稳定性高于个体水平。



Abstract:Carbon(C) and nitrogen (N) stoichiometry are critical indicators of biogeochemical coupling in terrestrial ecosystems. Besides, the stoichiometric homoeostasis plays an important role in regulating structure, functioning and stability of ecosystems. So far, researches of C:N stoichiometry in plants were concentrated on aboveground leaves. Knowledge on belowground roots remains unclear. In this study, roots of 22 plant species were sampled in Nanji wetlands of Poyang Lake. Subsequently, C and N concentration were measured based on root orders. The results showed that the variation range was from 267.15 to 423.22 mg/g for root C, 2.22 to 31.05 mg/gfor root N and 2.27 to 71.78 for root C:N ratio, respectively. C, N, and C:N ratio of the first-order roots were significantly correlated with the second-root orders, but not with the third-order roots. C concentration and C:N ratio increased with root orders, whereas N concentration decreased with root orders. Hence, it is necessary to separate root orders for plants C and N stoichiometry researches in wetlands. Moreover, root orders, species and their interaction all significantly affected root C, N, and C:N ratio. Root C:N ratios were not significantly different between high floodplain meadow and low floodplain marsh, suggesting that root C:N stoichiometry was more constrained at community level than individual level in Nanji wetlands of Poyang Lake.





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