黄河三角洲湿地不同植被群落下土壤养分含量特征

以黄河三角洲潮上带湿地为对象，通过采样、分析，研究了4种典型的植被群落下水盐梯度和土壤养分含量的变化特征。结果显示．沿植物群落演替方向，土壤水分含量无显著差异，土壤盐分呈逐渐降低的趋势，在一定程度上反映了植物群落的不同演替阶段。在这种水盐梯度下，植被群落的变化能够影响土壤养分含量，沿着植被演替方向，全碳与有机质含量随着演替方向呈先逐渐降低后增加的趋势，土壤碳氮比（C／N）在植被演替中期相对较高；全氮含量沿着演替方向呈现增加趋势，硝态氮与铵态氮先增加后降低；全磷与有效磷随演替变化系数较小，演替中期各理化性质变异系数相对较大。各群落土壤C／N值均小于25。相关分析表明，全氮、有机质与有效磷两两显著相关（p〈0.01），有效磷还与含水率显著相关（p〈0．05），硝态氮、铵态氮和全磷未显示出与其他理化性质的相关关系。含水率与pH值显著相关（p〈0．05），且二者均与土壤盐分显著负相关（P〈0．01）。

Soil Nutrient Contents in Yellow River Delta Wetlands with Different Plant Communities

Soil nutrient contents were measured in 31 study plots of the supratidal zone wetland of Yellow River Delta（ YRD ） in order to reveal their changes in marsh soils with different plant communities. By the methods of spatial distribution as a substitute for time succession, different plant communities were chosen to substitute different periods of plant community succession. Results showed that there were obvious relationships among four plant communities and soil salt contents （SC） but there were no significant differences among water contents （WC）, which also showed different succession periods of plant community to some certain. Along the positive succession direction of pant communi- ty, both the contents of soil organic matter（SOM ） and their variation coefficients showed the trend of ＂decreasing before increasing＂ along the water-salt gradients. The ratios of C/N were relatively higher in the middle of the successions than at the beginning or later stage. Total nitrogen（TN） contents showed an increase while NH4＋-N and NO3--N showed the trends of ＂decreasing after increasing＂. Total phosphorus （TP） contents had no significant variations with the succession. No significant differences were observed in total phosphorus （TP） and available phosphorus（ AP ） contents of wetland soils under four plant communities. The middle of the succession had the higher variation coefficients. In wetland soils under four plant communities, the ratios of C/N were all lower than 25. Correlation analysis showed that there were significantly positive correlations between TN ,SOM and AP（P〈0.01 ）. TP was significantly positively correlated with WC （P〈0.05）. No significant correlations were found between NH4＋-N ,NO3--N and TP with other soil properties. WC were significantly positively correlated with pH（P〈0.05 ） and both of them were negatively correlated with SC（P〈0.01 ）.