Characteristics of fractal dimension of soil particles in alkali grasslands of Anda City

The model of mass fractal dimension was used to analyze the mechanical composition of soil particles for the sample plots of Leymus chinensis and alkali land in Anda City of Heilongjiang Province,and the regression equation between fractal dimension and diameters of soil particles was established.The purpose is to provide a general comprehension for the relationship between soil physical properties and fractal dimension affected by soil alkalinization,and to present a new heuristic idea to regional-level management of ecosystem in the Anda City and Songnen Plain.The results showed that fractal dimensions in the Anda City are relatively big,which represents the content of fine soil particles is high,the quantity of macropore is little,and saturated hydraulic conductivities are low(averagely 48.7×10^-5 cm/s in Pit A and 4.30×10^-6 cm/s in Pit B).Between fractal dimension and clay content there is a positive correlative relationship but no significant correlation between fractal dimension and silt or sand content,which showed the main decisive factor on fractal dimension of soil particles is clay content in the experimental area of Anda City.In addition,the variation of fractal dimension in the soil profile of the Leymus chinensis land was bigger than that in the alkali land,which indicated the growth of vegetation may promote the variation of soil particles distribution.The fractal dimensions of the alkali land were significantly greater than those of the Lermus chinensis land because of more fine particles and higher saturated hydraulic conductivity in the alkali land.This showed that the formation of alkali plots exacerbated the soil physical properties,and the fractal dimension can be used as an index to evaluate the soil physical properties and to appraise the status of soil degeneration and eco-environment deterioration.