松嫩草地不同退化阶段的土壤团聚体稳定性

受人类不合理利用和气候影响的综合作用,松嫩草地退化程度逐渐加剧。本研究选取羊草(Leymus chinensis)群落、虎尾草(Chloris virgata)群落、碱茅(Puccinellia distans)群落和碱蓬(Suaeda glauca)群落作为4个草地退化阶段,通过调查植被群落特征、分析土壤理化性质,测定土壤团聚体稳定性指标,揭示草地植被退化过程中对土壤结构的影响。结果表明,随着退化演替的进行,植被生物量、物种多样性指数和总盖度总体上均呈现为降低的趋势;土壤含水率、有机质含量和全氮均降低,而pH和容重均增加,且4种退化演替阶段的土壤pH均高于8.0;土壤水稳性团聚体的粒径分布中微团聚体(0.25mm)所占比例增加,大团聚体(0.25mm)所占比例和水稳性团聚体的稳定性递减,且在同一退化阶段的0-30cm各土层呈现出水稳性团聚体的稳定性随土层深度增加而稳定性递减的趋势。研究结果对揭示松嫩草地不同退化阶段土壤团聚体稳定性特征以及退化草地恢复重建均有重要指导意义。

Research of soil aggregate stability in different degradation stages of Songnen grassland

Due to the combined effects of overuse by humans and climate changes, the Songen grassland is rapidly degrading, and the influence on soil structure and function have become a serious issue.In this study, four grassland communities (Leymus chinensis, Chloris virgata, Puccinellia distans, and Suaeda glauca communities) were selected as representatives of different degradation stages.To reveal the effect of degradation on soil structure and anti-erodibility, samples of vegetation, soil profiles, and surface soil were taken to the laboratory, where community characteristics, soil properties, and soil aggregate stability were analysed.Vegetation biomass, diversity index, and vegetation coverage generally declined with succession of degradation.Soil moisture, organic matter, and total N decreased, while pH and soil bulk density increased;the soil pH value of every stage of degradation was above 8.0.The size classes of water-stable soil aggregates had a trend such that the proportion of micro-aggregates increased, while the proportions of macro-aggregates and soil aggregate stability decreased.Within one degradation stage, soil aggregate stability decreased with increased soil depth in layers 0-10 cm to 20-30 cm.The results revealed the effects of the Songen grassland degradation on soil aggregate stability and have implications for the restoration of degraded grasslands.