向海湿地不同植被群落下土壤氮素的分布特征

Spatial Distribution of Nitrogen in Marsh Soils with Different Plant Communities in Xianghai Wetland

对比分析向海湿地8种植被群落下表层和亚表层土壤氮形态和全氮含量差异,研究不同植被群落下土壤氮素分布特征。结果表明,各植被群落下表层和亚表层土壤全氮主要以有机氮的形态存在;沼柳群落下表层土壤全氮含量最高,三棱群落最低;而香蒲群落下亚表层土壤全氮含量最高,碱蓬群落最低;根系分布较深的植物群落下表层和亚表层土壤氮素一般高于根系分布较浅的植物群落;除辣蓼群落下土壤无机氮以硝态氮为主外,其它各群落下土壤无机氮均以铵态氮为主。相关分析表明,土壤全氮和有机氮含量与土壤有机质含量显著正相关,与土壤pH值呈现显著负相关关系。

Contents of total nitrogen and nitrogen forms in surface and subsurface soils with eight different plant communities in Xianghai Wetland were measured and analyzed in order to study the spatial distribution characteristics of all nitrogen forms in marsh soils with different plant communities. Results showed that total nitrogen in marsh soils was dominantly composed with organic nitrogen. There were highest contents of total nitrogen in surface soils with Salix rosmarinifolia community, while lowest in the surface soils with Sparganium stotoniferum community. However, as for subsurface soils, the highest or lowest contents of total nitrogen appeared in Typha orietalia community and Suaeda acuca community, respectively. Nitrogen contents in surface and subsurface soils were higher in plant communities with deeper root system than those with shallower root system. Inorganic nitrogen in those soils mainly consisted of nitrate nitrogen for Polygonum hydropiper community, while ammonium nitrogen for other plant communities. Correlation analysis showed total nitrogen and organic nitrogen were significantly positively correlated with soil organic matter, but they showed significantly negative correlations with soil pH values.