Abstract:

In order to explore the effect of changes in plant communities and land use, brought out by anthropogenic disturbance, on soil properties, we applied the theory of fractals and hydrology as a means to quantify changes in particle-size distribution (PSD) and soil porosity. Fractal dimension analysis of PSD and soil porosity was determined for the 0-20 cm soil layer in different plant communities and land management styles in the Yimeng Mountain of the mid-eastern China. The results showed that, compared with that of the protected forest in preserve areas, soil physical properties in economic forestland (BL), cropland (TY) and mixed shrub-grass lands (GC) were more susceptible to soil degradation under their long-term management strategies. In general, amounts of silt and clay decreased under BL, TY, and GC land practices, while fine sand content increased, resulting in lower values of the fractal dimensions, soil total porosity and capillary porosity. For protected forests, soil physical properties were improved due to litter decomposition and plant root development under long-term preservation measures. The soil types in the studied area are typical of skeletal soils found in many mountainous areas. The relationship between fractal dimension and PSD and selected soil properties were also examined. There were significant correlations between fractal dimension and the amount of silt and clay, and fine sand (R²=0.83 and 0.64, respectively), with increasing fractal dimension values corresponding to higher silt and clay contents and lower sand content. There also existed strong linear relationships between fractal dimension and soil porosity with R² values ranging from 0.74 to 0.91. This study demonstrates that fractal dimension analysis may be used to better quantify differences in PSD and soil porosity associated with soil degradation caused by anthropogenic disturbance of plant community environments.

Key words: soil physical properties, soil particle size distribution, fractal dimension, soil pore, Yimeng Mountain