Effects of different governance patterns of small watershed on fractal features of soil micro-aggregates in the hilly areas of central Sichuan Basin

The exploration of the fractal features of soil micro-aggregates under different governance patterns of small watershed can provide scientific basis for vegetation restoration and for soil and water loss control in the hilly areas of Sichuan Hilly Basin. Thus this paper analyzed the composition and fractal features of soil micro-aggregates and its relationship with soil physicochemical properties. The results showed that soil micro-aggregates of 0.01-0.05 mm size were dominant aggregates in 0-10 cm soil layer (28.63%) and 10-20 cm soil layer (28.04%). This was followed by soil micro-aggregates of 0.001-0.005 mm size for 0-10 cm soil layer (25.90%) and 10?20 cm soil layer (26.33%). Significant differences were observed among different patterns of governance. The range of fractal features of soil micro-aggregates was 2.643-2.717. The sequence of fractal features of soil micro-aggregates for different governance patterns was conservation forest < orange forest < walnut forest < bare-land < slope-terrace < grading of slope land. Linear relation between fractal features and composition of soil micro-aggregates was observed. Fractal features of soil micro-aggregates showed significant positive correlations with available K and total K. However, negative correlations were noted between fractal features of soil micro-aggregates and total soil porosity, alkali-hydrolyzable N, total N and organic matter. The fractal features of soil micro-aggregates better reflected the physicochemical properties of soils in the hilly areas of central Sichuan Basin. Woodland was the best mode for vegetation restoration and controlling soil and water loss in the basin.