青藏高原高寒草原草甸土壤团聚体及养分因子变化特征

为探讨青藏高原高寒草原草甸的土壤团聚体稳定性及有机碳等养分因子的变化分布，在青海省三江源区高寒地带选取样点分层采集土壤样品，进行室内测定并分析2种植被下土壤团聚体和养分因子的变化特征。结果表明：研究区土壤>0.25 mm水稳性团聚体含量（WSA）、平均质量直径（MWD）与几何平均直径（GMD）均为草甸>草原，而分形维数（D）与结构体破坏率（PAD）为草原>草甸，即青藏高原高寒草甸土壤团聚体稳定性大于高寒草原。高寒草甸土壤稳定性及养分含量随土层深度增加显著降低（P<0.05），草原土壤稳定性和养分含量随土层深度无显著变化趋势。高寒草原土壤稳定性与各养分含量随海拔升高而降低，高寒草甸土壤团聚体稳定性与养分随海拔升高先降低后增加。高寒草甸土壤团聚度与养分含量呈极显著相关（P<0.01），高寒草原土壤团聚度与养分无显著相关；>4，4~2，2~1 mm粒级团聚体是影响研究区土壤养分含量的主导粒径，其稳定性程度主要受大团聚体作用。研究结果对于青藏高原土壤质量评价、生态环境保护具有重要科学意义。

Changes of Soil Aggregates and Nutrient Factors in Alpine Grassland and Alpine Meadow of Qinghai Tibet Plateau

In order to study the stability of soil aggregates and the distribution of organic carbon and other nutrients in alpine grassland and alpine meadow on the Qinghai Tibet Plateau, in this study, soil samples were collected from the alpine region of the Qinghai Tibet Plateau, the changes of soil aggregates and nutrient factors were measured and analyzed in the laboratory. The results showed that: >0.25 mm percentage of water-stable aggregates (WSA), mean weight diameter (MWD), and geometric mean diameter (GMD) in the alpine soil of the Tibetan plateau were meadow>grassland, the fractal dimension (D) and the aggregate processing damage rate (PAD) were grassland>meadow. Therefore, on the Qinghai Tibet Plateau the stability of soil aggregates in the alpine meadow was higher than that in the alpine grassland. The soil stability and nutrient content of alpine meadow decreased significantly with the increase of soil depth (P<0.05), while the soil stability and nutrient content of grassland showed no significant change trend with the increase of soil depth. The soil stability and nutrient content of alpine grassland decreased with the increase of altitude, while that of alpine meadow decreased firstly and then increased with the increase of altitude. There was a significant correlation between soil agglomeration degree and nutrient content in alpine meadow (P<0.01), while there was no significant correlation between soil agglomeration degree and nutrient content in alpine grassland. Aggregates of >4, 4~2, and 2~1 mm were the main factors that affect the content of soil nutrients, and the stability of soil aggregates was mainly affected by macro-aggregates. The results of the study have important scientific significance for soil quality evaluation and ecological environment protection in the Qinghai Tibet Plateau.