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论文以黄土台塬不同土地利用方式为对象,采用几何平均直径(GMD)、平均重量直径(MWD)、分形维数(D)、破坏率(PAD)、峰凸系数(CE)和偏倚系数(CS)对其土壤>0.25 mm团聚体进行分析,探讨土地利用方式转变对土壤团聚体水稳性的影响及其最佳评价指标的选择。结果表明:不同利用方式土壤团聚体含量、GMD及MWD均表现为耕地<乔灌混交林地<乔木林地<天然草地<灌木林地;林和草的种植有利于促进土壤较大粒径团聚体的形成,其土壤1~5mm粒级团聚体占>0.25 mm团聚体总量比重显著(53.90%~80.20%),结构非均匀性明显(灌木林地和天然草地土壤尤为突出);而耕地土壤0.25~1 mm粒级团聚体占>0.25 mm团聚体总量比重较大(约81%),结构呈均匀性;林地和草地土壤剖面由上而下团聚体优势粒径逐渐变小,结构差异逐渐减弱,该趋势灌木林地和天然草地较为缓慢,而耕地在整个剖面上均呈优势粒径较小,结构均一;GMD和CS可较好地衡量整个剖面土壤团聚体水稳性,而PAD可更好地描述0~20 cm深度。
In this paper, different land use patterns of the Loess Plateau were selected as the research objects. The geometric mean diameter (GMD), average diameter of the diameter (MWD), fractal dimension (D), damage rate (PAD), peak convexity coefficient (CE) and bias coefficient CS) was used to analyze the aggregates> 0.25 mm in soil so as to explore the effect of land use change on the water stability of soil aggregates and the selection of the best evaluation index. The results showed that the content of soil aggregates, GMD and MWD in different land use types were all in the fields of “mixed stands of tree and shrub” natural grassland 0.25 mm accounted for 53.90% ~ 80.20% of total aggregates, and the structural heterogeneity was obvious (especially in shrub land and natural grassland); while the contents of 0.25 ~ 1 mm aggregates accounted for more than 0.25% aggregates (about 81%), and the structure was uniform. The dominant particle size of aggregates from top to bottom in forestland and grassland gradually became smaller and the structural differences gradually weakened, The trend of shrub land and natural grassland is relatively slow, while the cultivated land in the entire cross section showed a smaller average particle size, uniform structure; GMD and CS can better measure the water cross-section soil aggregate stability, and PAD better Depicts 0 to 20 cm depth.