黄河三角洲湿地不同植物群落土壤盐分分布特征

为研究黄河三角洲地区不同植物群落下土壤盐分含量的空间变化特征,以及盐分指标之间的关系,于2012年10月利用经典统计分析、变异分析等方法,开展了植物样地调查和土壤剖面采样分析。结果表明:研究区属于重盐土类型(含盐量>4.0 g·kg^-1)。水平方向沿柽柳群落-碱蓬群落-芦苇群落-棉花群落演替,土壤盐分含量呈逐渐降低之势。垂直方向上:柽柳群落和碱蓬群落土壤盐分随土壤深度的增加而减小,土壤盐分表现出明显的表层富集特征;芦苇群落和棉花群落土壤盐分表现为随土壤深度增加先增大后减小的趋势。盐分在不同植物群落类型中大多属于中等强度变异性,但是,柽柳群落中的SO42-、芦苇群落中的Mg²⁺和Cl^-在水平方向上表现出强烈的变异性,碱蓬群落中的CO32-在水平和垂直方向均表现出强烈的变异性,棉花群落中的CO32-在垂直方向上表现出强烈的变异性。在0~80 cm的土壤剖面土体中,K⁺、Na⁺、Ca²⁺、Cl^-和HCO3-在前述4种植物群落中差异显著(P<0.05),而Mg²⁺、SO42-、CO32-则无明显差异。土壤中Cl^-含量与土壤全盐含量呈极显著相关(P<0.01)。因此,控制或减少Cl^-投入可能是一条减轻黄河三角洲地区土壤盐渍化程度的合适途径。

Characteristics of spatial distribution of soil salinity under different plant communities on wetland in Yellow River Delta

To assess the spatial distribution of soil salinity and correlations among different indices of salinity in the Yellow River Delta, an investigation of vegetation quadrats and soil samples was carried out by using the classical statistical and variance analysis in October, 2012. It was shown that soil salinity in the study area belonged to heavy salinity, as salt content was above 4.0 g^.kg^-1. There was a clear gradient in soil salinity in the order of Tamarix chinensis community>Suaeda salsa community>Phragmites australis community>cotton community. Vertically, soil salinity increased with soil depth in Suaeda salsa and Tamarix chinensis communities, while the soil salinity was the highest in the sub-surface soil in Phragmites australis and cotton communities. Variable coefficient of soil salinity in the study area was mostly moderate, yet there was a strong spatial variability of individual ions, such as SO42- in Tamarix chinensis community, and Mg²⁺ and Cl^- in Phragmites australis community in the horizontal direction, CO32- in the Suaeda salsa community in both horizontal and vertical directions, and CO32- in the cotton community in vertical direction. In 0-80 cm soil layer, the concentrations of K⁺,Na⁺,Ca²⁺,Cl^- and HCO3- were significantly (P<0.05) different among plant communities, while Mg²⁺,SO42- and CO32- showed no significant difference. Contents of Cl^- exhibited a significant (P<0.01) correlation with soil salinity. Therefore, controlling or reducing Cl^- input might be an optional approach to alleviate soil salinization in the wetland of Yellow River Delta.