Analysis of Difference in Surface Soil Aggregate Stability of Typical Vegetation Types in Purple Soil

In the Qinling small watershed of Zhongxian County, situated within the hinterland of the Three Gorges Reservoir region, 7 representative vegetation types of Cupressus funebris, Pinus massoniana, Eucalyptusspp., Citrus reticulata, shrub, grassland and maize were selected to examine the variations in soil aggregate stability across different vegetation categories and to analyze the factors influencing these variations. The result showed the content of soil aggregates >0.25mm (WSA_>0.25), mean weight diameter (MWD), and geometric mean diameter (GMD) varied from 27.12–91.79%、0.71–5.61 mm and 0.25–4.00 mm among different vegetation types. And maize land had the minimum mean WSA_>0.25, MWD and GMD, whereas shrubland of Vitex negundo had the maximum ones. The stability of soil aggregate is comprehensively affected by soil properties and vegetation characteristics. The WSA_>0.25, MWD and GMD were significantly positively correlated with soil organic matter content, WSA_>0.25 was significantly positively correlated with plant root mass density, and MWD was significantly positively correlated with plant litter accumulation. However, WSA_>0.25, MWD and GMD increased logarithmically with the increase of soil organic matter content, litter accumulation, and root mass density. The result of redundancy analysis showed that soil organic matter content, clay content, and plant litter accumulation were the main factors attributing to the differences in soil aggregate stability.