盐生荒漠植物群落土壤氮素含量及其组分特征

为了探讨盐生植物群落土壤氮素含量及组分特征,以新疆艾比湖流域盐生荒漠土壤为研究对象,分析了乔木、灌木和草本3种不同生长型盐生植物群落0～20、20～40和40～60 cm的土壤理化性质及各形态的氮素含量。结果表明,研究区不同生长型盐生植物群落土壤pH、电导率、有机质和C/N随土层深度增加而逐渐降低,而含水量与之相反。同一土层,土壤总氮、有机氮和氮密度呈现从乔木、灌木再到草本盐生植物群落逐渐增加的趋势。垂直分布方面,不同生长型盐生植物群落的土壤各形态氮素含量和氮密度均随着土层深度的增加而降低,表聚现象明显。除铵态氮以外,其他各种氮素间均表现为极显著正相关(P0.01),且与土壤有机质、含水量和容重呈极显著相关(P0.01)。土壤各形态氮素占总氮的比例对总氮的变化存在不同的响应,有机氮占总氮的比例相对稳定,有机氮与碱解氮占总氮的比例随总氮含量的增加而增加,无机氮、硝态氮和铵态氮占总氮的比例随总氮含量的增加而降低。

Soil Nitrogen Content and Components Under Different Halophyte Communities in Saline Desert

In order to investigate soil nitrogen content and composition characteristics under halophytic vegetation, soil properties and nitrogen contents in the depths of 0-20 cm, 20-40 cm and 40-60 cm in different halophyte communities were studied in a saline desert in Ebinur basin. The results showed that soil pH, conductivity, organic matter and C/N under different halophyte communities gradually decreased with the increase of soil depths, whereas water content showed an opposite trend. In the same soil depth, total nitrogen, organic nitrogen and nitrogen density were in the order of trees < shrubs < herbs. Along soil profile, the contents of different nitrogen forms and nitrogen density under different halophyte communities gradually decreased with increase of soil depths, indicating a phenomenon of surface aggregation. Except for ammonium nitrogen, there were significant correlations between soil organic matter, water content and bulk density and different nitrogen forms (P<0.01), and there also were significant positive correlations among different nitrogen forms (P<0.01). In addition, the ratios of nitrogen different forms to total nitrogen exhibited different responses to total nitrogen, the ratio of organic nitrogen to total nitrogen was relatively stable, the ratios of organic and alkali-hydrolyzale nitrogen to total nitrogen increased with the increase of total nitrogen, whereas, the ratios of inorganic, nitrate and ammonium nitrogen to total nitrogen decreased with the increase of total nitrogen content.