鄱阳湖湿地植物群落碳氮磷化学计量格局与内稳性研究

Researches on regional spatial-temperoal stoichiometric patterns in foliar carbon,nitrogen and phosphorus were concentrated at individual level, however, C:N:P stoichiometry at community level was still poorly understood. In this study, the typical Poyang lake wetland located at the front edge of Ganjiang delta will be selected as research sits.Subsequently,the plant communities investigation will be conducted along water table gradient in growing season. Combined with dynamic monitor of dominant plant communities, as well as field nitrogen and phosphorus addition experiment, C:N:P stoichiometric patterns and homeostasis of wetland plant communities will be studied. The objectives of this study are :1) to clarify effects of water table changes on C:N:P stoichiometry in dominant and non-dominant plant species, as well as aboveground and belowground parts of communities both at temporal and spatial scales. 2) to discuss the C:N:P stoichiometric difference between individual and community level. 3) to reveal the stoichiometric mechanism responsible for the structure and stability of plant communities developed in Poyang lake wetlands with drastic water table fluctuations. The results of this study will not only help to understand the adaptation of wetland plants to water table fluctuation, but also provide valuable references for biodiversity protection and degraded wetland restoration in the context of climate warming and wetland drought.

区域碳(C)、氮(N)、磷(P)化学计量格局的信息多见于个体水平，植物在群落水平上是否存在与个体类似的化学计量关系目前仍不清楚。本项目拟选择鄱阳湖湿地典型区-赣江三角洲前缘地带，于植物生长季沿水位梯度对常见植物群落进行调查与样品采集，并结合优势植物群落年际动态监测与N、P添加试验，开展湿地植物群落C、N、P化学计量格局与内稳性研究，在时间和空间两个维度上阐明水位变化对鄱阳湖湿地植物群落优势种与伴生种以及群落地上与地下部分C、N、P化学计量特征的影响；探讨个体水平与群落水平的化学计量差异；揭示鄱阳湖高动态水情环境下发育的湿地植物群落结构与稳定性维持的化学计量学机制。项目研究结果不仅有助于理解鄱阳湖湿地植物对水位变化的适应机制，还将对气候变暖与湿地干旱化趋势下的生物多样性保护与退化湿地的恢复具有重要参考价值。

区域碳(C)、氮(N)、磷(P)化学计量格局的信息多见于个体水平，植物在群落水平上是否存在与个体类似的化学计量关系目前仍不清楚。本项目自北向南分别选择鄱阳湖湿地典型区—星子、吴城、鄱阳和南矶，于植物生长季沿水位梯度采集常见植物的地上叶、茎和地下根系及土壤样品，并结合优势群落年际动态监测与N、P添加实验，以探讨鄱阳湖湿地植物C、N、P化学计量格局与内稳性特征。结果表明：（1）个体水平上，鄱阳湖湿地植物C、N、P含量变化范围分别为218.65~464.46 mg·g-1、5.02~46.97 mg·g-1和0.48~4.15 mg·g-1；C:N、N:P和C:P变化范围分别为6.88~86.66、3.52~34.82和86.78~846.64，N、P含量之间极显著正相关（P＜0.001）。从挺水、湿生、浮水到沉水植物，C、N、P含量总体上遵循地上叶片>茎>地下根系的规律。（2）群落水平C、N、P含量及其化学计量关系与优势种没有显著性差异，可以用各群落优势种替代。这主要是由于鄱阳湖湿地植物群落结构简单，物种组成少，优势物种的生物量占据群落总生物量的90%以上。（3）无论年内还是年际，湿地植物群落C、N、P含量及其化学计量关系均发生一定的波动，特别是N和P具有显著的年内与年际变化。生物量的变化是引起植物N、P元素变化的主要因素。总体上，C的稳定性远高于N和P，C:N的稳定性要高于N:P与C:P，地上叶片的C、N、P及其化学计量比的稳定性高于地下根系。（4）鄱阳湖湿地植物叶片N、P含量对土壤P的变化较N的变化更敏感。叶片N:P化学计量关系具有保守性特征，不随土壤N、P养分变化而产生显著差异；根系N:P化学计量关系的稳定性低于叶片，在不同的土壤N环境下发生了显著变化。.