黄浦江上游水源涵养林土壤团聚体组成及其碳、氮分布特征
Composition of Soil Aggregate and Distribution Characteristics of Its Organic Carbon and Total Nitrogen in Water Conservation Forest Located in the Upper Reaches of the Huangpu River

作为土壤结构的基本单元,土壤团聚体是反映土壤肥力的一项重要指标。不同土层各粒级团聚体在营养元素的保存、传递和转化等方面发挥着不同的作用。试验选取了上海城市森林生态系统定位观测研究站黄浦江上游水源涵养林观测点的四块典型阔叶混交林,研究其不同土层土壤团聚体组成及其有机碳和全氮的分布特征,进一步探究不同土层各粒级团聚体对土壤的养分贡献率。结果表明:(1)土壤团聚体含量随其粒径的减小而增加,<53 μm粒径土壤团聚体在分布中占主导地位,同时大团聚体含量与土层深度呈负相关;(2)有机碳含量随团聚体粒径的减小而减少,随土层深度的增加而降低;(3)土壤团聚体全氮含量变化规律与有机碳趋于一致,但大团聚体的碳氮比均显著高于微团聚体;(4)粒径<250 μm的微团聚体对土壤的有机碳和全氮贡献率高达85% 以上。研究结果在一定程度上揭示了黄浦江上游水源涵养林土壤团聚体的组成及其碳、氮元素分布特征,为衡量和改善区域土壤质量提供了理论依据。
As the basic unit of soil structure,soil aggregate is an important indicator of soil fertility.In different soil layers,different particle fractions of aggregates play different roles in the preservation,transport and transformation of nutrients.Four typical broad-leaved mixed forests in the water conservation forest located in upper reaches of the Huangpu River were selected as experimental plots.The study focused on soil aggregate composition and distribution characteristics of organic carbon and total nitrogen,and further explored the nutrient contribution rate of soil aggregates.The main conclusions are as follows.(1) <53 μm particles constitute the largest proportion in soil aggregates and the content of large aggregate decreases with soil depth.(2) Organic carbon content correlates positively with aggregate size but negatively with soil depth.(3) Total nitrogen content has similar distribution characteristics in soil aggregates compared to organic carbon,and the C/N ratios of large aggregates are significantly higher than those of microaggregates.(4) Over 85% of organic carbon and total nitrogen distributes in microaggregates (<250 μm).Our results revealed the composition of soil aggregates and the distribution characteristics of its organic carbon and total nitrogen in the study area,and provided theoretical basis for measuring and improving the local soil quality.