鄱阳湖湿地植物群落分布特征

通过研究鄱阳湖典型洲滩湿地4种植物群落带下各土壤环境因子的含量变化特征，结合研究区20个植被样方的典范对应分析（Canonical Correspondence Analysis，CCA）排序，分析了鄱阳湖典型洲滩湿地主要土壤环境因子及其对植被分布的影响。结果表明:Jaccard指数、Sorensen指数和Cody指数均表现为:藜蒿—苔草带 < 芦苇—藨草群落 < 苔草—狗牙根群落 < 苔草—藨草群落，随生境梯度呈递减规律，而Bray curtis指数则表现为藜蒿—苔草带 > 芦苇—藨草群落 > 苔草—狗牙根群落 > 苔草—藨草群落，随生境梯度呈递增规律。土壤总有机碳、全氮、硝态氮、铵态氮呈一致的变化规律，均表现为苔草—藨草群落 > 芦苇—藨草群落 > 苔草—狗牙根群落 > 藜蒿—苔草带，而土壤速效磷表现为藜蒿—苔草带 > 苔草—狗牙根群落 > 芦苇—藨草群落 > 苔草—藨草群落，不同植被带土壤全磷含量差异均不显著（p > 0.05）。相关性分析表明，不同植被带Bray curtis指数均与土壤养分呈负相关，Jaccard指数、Sorensen指数和Cody指数均呈正相关，沿河岸带的增加，其相关系数的绝对值逐渐增加，而土壤磷素与湿地多样性指数没有显著的相关性（p > 0.05）。CCA排序分析表明:土壤环境因子具有明显的生态梯度，土壤总有机碳是影响研究区植被分布的最主要因素，土壤全氮是影响湿地植被分布的次要土壤环境因子。

Characteristic of Vegetation Distribution in Typical Shoaly Wetlands of Poyang Lake

Investigations of variation of various soil environment factors in content in typical shoaly wetlands of the Poyang Lake under four different kinds of plant communities were carried out, and canonical correspondence analysis on the 20 vegetation sampling plots in the research zone was performed to analyze the major soil environment factors of the shoaly wetlands and their effects on vegetation distribution. The results showed that Jaccard, Sorensen and Cody index followed the order: Artemisia—Carex < Phragmites—Scripus triqueter < Carex—Cynodon dactylon < Carex—Scripus triqueter with the habitat gradient, while Bray curtis index showed the opposite change trend with the habitat gradient; soil total organic carbon, soil total nitrogen, soil nitrate nitrogen and soil ammonium nitrogen showed the same change, following the order: Artemisia—Carex > Phragmites—Scripus triqueter > Carex—Cynodon dactylon > Carex—Scripus triqueter, and soil available phosphorus increased in the order: Artemisia—Carex < Phragmites—Scripus triqueter < Carex—Cynodon dactylon < Carex—Scripus triqueter, while contents of soil total phosphorus in different plant communites were no significant difference (p > 0.05). Correlation analysis showed that Bray curtis index was negatively correlated to soil nutrients, and Jaccard, Sorensen and Cody index were positively correlated to soil nutrients. The absolute values of the correlation coefficients increased with the increase of distance from riparian zone. Canonical correspondence analysis showed that soil environmental factors had the obvious ecological gradients, and soil total organic carbon is the major factor and soil total nitrogen is also one of the important soil environment factors affecting distribution of vegetation in wetlands.