科尔沁沙地沙丘-草甸相间地土壤颗粒的分形特征

选择科尔沁沙地典型沙丘-草甸相间地为研究区,利用土壤颗粒的体积分形模型计算了研究区49个采样点土壤颗粒的分形维数,并建立了分形维数与土壤颗粒不同粒级间的相关关系,以探讨半干旱寒冷地区土壤颗粒的分形特征与土壤物理性质以及养分含量之间的关系。结果表明:(1)研究区土壤颗粒的分形维数为1.33~2.50,变幅较大,且呈现出自中部的草甸、农田地带向南、北方向的沙丘地带递减的趋势;土壤颗粒的体积分形维数依照流动沙丘-半流动半固定沙丘-固定沙丘-农田-草甸的顺序而递增。(2)土壤颗粒的分形维数与黏粒、粉粒含量显著正相关,与砂粒含量显著负相关,且表现出明显的对数关系。100 μm是影响土壤颗粒分形维数变化的分界粒径,大于该粒径的颗粒含量越高,土壤颗粒的分形维数越小;反之越大。(3)分形维数与土壤养分含量相关显著,土壤颗粒的分形维数与电导率、pH值及有机质、全氮、全磷含量均显著正相关,但与全钾含量负相关。在分形维数大于2时,基本与土壤饱和含水率正相关、与干容重负相关。

Soil Particle Fractal Dimension in the Dune-meadow Ecotone of the Horqin Sandy Land

The volume fractal dimension model was used to calculate the particle fractal dimension of 49 sampling points in the dune-meadow ecotone in the Horqin Sandy Land and established the relationship between fractal dimension (D) and the different particle level for discuss the correlation between soil fractal dimension and the soil physical properties as well as soil nutrient in semiarid cold area. Resulted showed that: (1) Soil fractal dimension varied from 1.33-2.50 and it had a tendency of decrease from the meadow, farmland in the middle of the study area to the sand dune in the north and south. The fractal dimension has the significantly difference of the different landforms and different landuses. Soil fractal dimension increased in the following order: sand dunes-semi-mobile and semi-fixed dune-fixed dune-farmland-meadow. (2) Fractal dimension was significantly positively logarithmic correlated with clay content and silt content, but significantly negatively logarithmic correlated with sand content. 100 μm diameter can be regarded as a critical diameter .The more the \{>100\} μm content, the lower the fractal dimension; otherwise, the higher fractal dimension. (3) There existed significant correlations between fractal dimension and soil nutrient. The correlation between fractal dimension and electronically conductively, pH, the content of SOM, total nitrogen, total phosphorus was significantly positive, but negative with total potassium. When fractal dimension is larger than 2, the correlation between D and bulk density was negative. But, its positive with saturation moisture content.