Abstract: To investigate the relationship between soil aggregates and nitrogen in an alpine meadow, the variation characteristic of soil nitrogen and aggregates in different soil layers of alpine meadow with different degradation degrees in the eastern Qilian Mountains were studied, and the relationship between soil aggregates and nitrogen was discussed. The results showed as follows:With the deepening of the soil layers and the deterioration of the degrees, the content of total nitrogen, mineral-associated organic nitrogen, particulate organic nitrogen, ammonium nitrogen and nitrate nitrogen decreased gradually. The content of organic nitrogen decreased by 75.82% and inorganic nitrogen decreased by 59.36%, indicating that organic nitrogen was more sensitive to grassland degradation than inorganic nitrogen. With the deterioration of the degrees, the large aggregates decreased by 91.09% and the small aggregates increased by 70.62%, and the particle size of soil aggregates changed from the large aggregates to the small aggregates. With the deterioration of the degrees, the decrease of organic nitrogen content impaired the formation of soil aggregates, the mean weight diameter of soil aggregates gradually decreaseed, the fractal dimension of soil aggregates gradually increased, the stability of soil aggregates gradually decreased, which reduced the fixation capacity of aggregates to nitrogen, lead to the loss of nitrogen, thus prevented the accumulation of nitrogen pools.

Key words: Eastern Qilian Mountains, Alpine meadow, Degradation, Organic nitrogen, Inorganic nitrogen, Aggregate

摘要： 为探明高寒草甸土壤团聚体与氮素的关系，本试验研究了祁连山东段不同退化程度的高寒草甸上的不同土层土壤氮素和团聚体的变化特征，探讨了团聚体与土壤氮素的关系。结果表明：随着土层的加深和退化程度的加重，全氮、非颗粒有机氮、颗粒有机氮、铵态氮、硝态氮含量逐渐减小，有机氮含量降低75.82%，无机氮含量降低59.36%，说明与无机氮相比有机氮对草地退化的响应更敏感；随着退化程度的加重，土壤大团聚体数量降低91.09%，小团聚体数量增加70.62%，团聚体组分由大团聚体向小团聚体转变为主；随着退化程度的加重，有机氮含量降低影响土壤团聚体的形成，土壤团聚体平均重量直径逐渐降低，土壤团聚体分形维数逐渐增大，土壤团聚体稳定性逐渐下降，降低团聚体对氮素的固定能力，从而导致氮素流失，进而影响土壤氮库的储量。

关键词: 东祁连山, 高寒草甸, 退化, 有机氮, 无机氮, 团聚体