恒湖农场茶叶港草洲枯水期湿地植物与土壤关系及种群生态位分析

湿地植物与土壤关系问题一直就是生态学研究的热点,也是湿地植物种群生态位研究的基础。基于鄱阳湖典型湿地-|恒湖农场茶叶港草洲19个样地20种植物重要值组成的样地-|物种矩阵,用等级聚类分析中的Ward法(离差平方和法)将研究区植物划分为灰化薹草(Carex cinerascens)群落、虉草(Phalaris arundinacea)群落及南荻(Triarrhena lutarioriparia)群落3个群落类型。通过Spearman秩相关分析检验物种多样性指数(Shannon-Wiener多样性指数H'、物种丰富度指数S和Pielou均匀度指数J)与土壤因子(土壤pH值、电导率、含水量和有机质)的相关性,结果发现研究区植物物种的Shannon-Wiener多样性指数H'、物种丰富度指数S与土壤pH值分别为显著(P0.05)和极显著(P0.01)正相关关系,而与土壤有机质分别达到显著(P0.05)和极显著(P0.01)负相关水平,Pielou均匀度指数J与土壤因子相关性不明显。利用RDA(冗余分析)排序分析研究区植物物种分布与土壤p H值、电导率、含水量、有机质的关系,结果发现土壤pH值、土壤有机质与研究区植物物种分布关系最为密切(P=0.042,0.048),可以看成是关键控制因子。基于对研究区植物物种分布影响较大的土壤pH值及有机质环境因子,将其分别划分为10个梯度等级,分析植物种群生态位。发现研究区优势种灰化薹草、虉草生态位宽度较大,蚊母草(Veronica peregrina)、荇菜(Nymphoides peltata)等生态位宽度较小,生态位重叠值整体保持在较低水平,说明物种在土壤pH值和土壤有机质两个环境梯度上生态位分化明显。

Analysis of wetland plant-soil relationships and population niches in Chayegang marshland near Henghu farm in the Poyang Lake region during the dry season

Interactive effects exist among soil, vegetation, hydrology and climate in wetland areas, affecting the charateristics of wetland ecosystems. Wetland soil is usually a product of long-term interactions between ecological environment factors and plays a vital role in preserving the regional ecological balance. The factors that influencewetland vegetation include biological and abiological variables, which soil of abiological variable has the most profound effect on wetland plant growth. Relationships between wetland plants and soil have always been a hot topic in ecology and also form the basis for plant population niches research. Based on a sample plot-species matrix of Importance Value (IV) of 20 species at 19 sampling plots in the Chayegang marshland of the Poyang Lake region near Henghu farm, we used the Ward cluster method of hierarchical clustering to divide the plants in the study area into 3 community types-Com. Carex cinerascens, Com. Phalaris arundinacea and Com. Triarrhena lutarioriparia. Spearman rank correlations results revealed that, when considering biodiversity indices (Shannon Wiener diversity index H'', species richness index S and Pielou evenness index J) and soil factors (soil pH, electrical conductivity, moisture and organic matter), there were significant positive correlations (P < 0.05) between H'' and soil pH, and highly significant positive correlations (P < 0.01) between S and soil pH; However, there were significant negative correlations (P < 0.05) between H'' and soil organic matter and highly significant negative correlations (P < 0.01) between S and soil organic matter. However, the Pielou evenness index J had no discernible correlation with soil factors. The relationships of plant species distribution with soil pH, electrical conductivity, moisture and organic matter were assessed using redundancy analysis (RDA); Results revealed significant relationships of plant distribution with soil pH and soil organic matter (P=0.042 and 0.048), which were regarded as the key soil factors that controlled species distribution.As soil pH and organic matter were determined to be the principal environmental factors that had a considerable influence on plant species distribution, both were divided into 10 gradient levelsto analyze the plant population niches. The results showed that the dominant species, C. cinerascens and P. arundinacea, had larger niche breadths, while Veronica peregrina, Nymphodes peltatum, and other specieshad smaller niche breadths. All plant species in the study area had relatively small niche overlaps on the whole, suggesting that the population niches had obvious differentiation in soil pH and soil organic matter gradients.