长江源区高寒草原和高寒草甸土壤粒径分布特征

为探究长江源区主要下垫面土壤空间异质性与粒径分布(PSD)非均匀性,运用分形理论描述高寒草原和高寒草甸2种下垫面土壤粒径分布特征,分析了2种下垫面土壤的分形维数特征差异及其与土壤颗粒组成的关系。结果表明: 研究区土壤颗粒粒径主要分布于100～800 μm,高寒草原土壤单重分形维数(D_V)为2.429～2.508,高寒草甸土壤D_V为2.697～2.743,高寒草原土壤质地偏粗,高寒草甸土壤质地偏细。土壤在20～30 cm深度质地最细,在0～10 cm层质地最粗糙;多重分形维数(容量维数D₀、信息熵维数D₁、关联维数D₂)均以高寒草原(0.896～0.961、0.828～0.887、0.725～0.819)高于高寒草甸(0.890～0.914、0.693～0.744、0.540～0.603),与高寒草甸相比,高寒草原土壤粒径分布范围更宽,土壤整体构造更复杂,土壤整体非均匀性更高。D_V与土壤黏粒、粉粒含量呈显著正相关,与砂粒含量呈显著负相关;D₁、D₂与黏粒、粉粒含量呈显著负相关,与砂粒含量呈显著正相关。土壤砂粒含量是土壤PSD非均匀分布及分形维数大小变化的主要因素。

Distribution characteristics of soil particle size in alpine steppe and alpine meadow in the source region of the Yangtze River,China

To explore the heterogeneity of spatial distribution and particle size distribution(PSD) in the main underlying surface soil in the source area of the Yangtze River, we used the fractal theory to describe the soil particle size distribution of alpine steppe and alpine meadow, and analyzed the difference of fractal dimension characteristics of soil of two different underlying surface and its relationship with soil particle composition. The results showed that soil particle size in the study area was mainly concentrated in 100-800 μm. The single fractal dimension(DV) of alpine steppe soil was 2.429-2.508, and that of alpine meadow soil was 2.697-2.743. The soil texture of alpine steppe was coarse, while that of alpine meadow soil was fine. Soil texture was the finest in the 20-30 cm depth, and the coarsest in the 0-10 cm layer. The multi-fractal dimension(capacity dimension D0, information entropy dimension D1, correlation dimension D2) of alpine steppe(0.896-0.961, 0.828-0.887, 0.725-0.819) was higher than that of alpine meadow(0.890-0.914, 0.693-0.744, 0.540-0.603). Compared with the alpine meadow, the alpine steppe had wider soil PSD, more complex soil structure, and higher soil heterogeneity. DV was positively correlated to clay and silt contents, and negatively correlated to sand content. D1 and D2 were negatively correlated with clay and silt contents, and positively correlated with sand content. Sand content was the main factor accounting for the non-uniform distribution of PSD and the changes of fractal dimension.