【摘要】 文章在具有典型特征的紫花针茅草原设置退化程度不同的各研究样地,旨在探讨高寒草原土壤团聚体的稳定性变化,并采用野外观测、土样采集、室内试验的方法,测定了土壤团聚体含量组成、平均重量直径(MWD)、几何平均直径(GMD)、团聚体破坏率(PAD)、分形维数(D)等指标。结果表明:退化高寒草原研究样地土壤机械稳定性、水稳性团聚体含量随着团聚体粒径的增大呈先减少后增加的变化趋势;随着退化程度的加剧和土层的加深,<0.25 mm粒级团聚体含量增加,水稳性团聚体含量高于机械稳定性团聚体含量,2～10 mm粒级团聚体含量减少,其含量变化则与前者相反;0～10 cm土层,土壤团聚体破坏率随着退化程度的加剧而增大,10～20 cm土层则呈相反变化趋势;各土层土壤机械稳定性、水稳性团聚体MWD和GMD随着退化程度的加剧而减小,其中轻度退化到中度退化是MWD、GMD减少的主要阶段;土壤团聚体分形维数随着退化程度加剧和土层加深而增大,<0.25 mm粒级团聚体含量与分形维数间呈极显著正相关(P<0.01)。研究样地0～30 cm土层范围内,随着退化程度的加剧和土层的加深,土壤团聚体稳定性变差。更多还原

【Abstract】 In order to study the change of soil aggregates stability in alpine steppe, different degraded sample plots were set up in the Stipa purpurea steppe with typical characteristics, and the methods of field observation, soil sample collection and laboratory test were used to study the stability of soil aggregates. The composition of aggregates content,mean weight diameter(MWD), geometric mean diameter(GMD), the percentage of aggregates destruction(PAD), fractal dimension(D) and so on were determined. The results showed that the content of soil mechanical-stable aggregates and water-stable aggregates of research sample plots in degraded alpine steppe decreased first and then increased with the increase of aggregates particle size. With the aggravation of degraded degree and the deepening of soil layer, the content of <0.25 mm aggregates increased and the water-stable aggregates content was higher than that of mechanicalstable aggregates, the content of 2～10 mm aggregates decreased and the change trend of 2～10 mm aggregates was opposite to the former. In 0～10 cm soil layer, the percentage of soil aggregates destruction increased with the increase of degradation degree, but the 10～20 cm soil layer showed an opposite trend. MWD and GMD of the mechanical-stable aggregates and water-stable aggregates decreased with the degree of degradation aggravating, and the light to moderate degradation is the main stage of the decrease of MWD and GMD in all soil layers. The fractal dimension of aggregates increased with the aggravation of degraded degree and the deepening of soil layer, the content of <0.25 mm aggregates and the fractal dimension were extremely significant positive correlation(P<0.01). Within the 0～30 cm soil layer of the sample plot, with the aggravation of degraded degree and the deepening of soil layer, the stability of soil aggregates become worse.更多还原