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

Investigating the differences in soil aggregate stability among typical vegetation types in purple soils of the Three Gorges Reservoir Area and identifying their influencing factors can provide a theoretical basis for optimizing vegetation selection during ecological restoration of degraded purple soils. Seven typical vegetation types of Cupressus funebris Endl., Pinus massoniana Lamb., Eucalyptus spp., Citrus reticulata Blanco, shrub, grassland and maize were selected in the Qinling small watershed of Zhongxian County in the hinterland of the reservoir area. The differences in soil aggregates stability were explored, and factors attributing to these differences were identified. The result showed (1) 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. (2) The stability of soil aggregate is comprehensively affected by soil properties and vegetation characteristics. The result of Pearson correlation analysis indicated that WSA_>0.25, MWD and GMD were significantly positively correlated with soil organic matter content (p<0.01), WSA_>0.25 was significantly positively correlated with plant root mass density, and MWD was significantly positively correlated with plant litter accumulation (p<0.05). However, WSA_>0.25, MWD and GMD increased logarithmically with the increase of soil organic matter content, litter accumulation, and root mass density. (3) 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.