Evolution of soil texture in mid-subtropical forests in the past 32 years: taking Fanjing mountain in Southwest China as an example

In order to explore the evolution pattern of forest ground force in Fanjing Mountain and provide a scientific basis for ecological management and forest restoration in the Fanjing Mountain area, the trend analysis method was used to study the evolution characteristics and patterns of soil texture at different elevation and profile levels in Fanjing Mountain in 1982 and 2014 after 32 years. The results show that the trend of increasing sand and clay and decreasing silt in the soils of Fanjing Mountain is evident, and the overall soil texture of Fanjing Mountain evolves from Silty loam to Silty clay loam. Soil sanding and claying coexist in Fanjing Mountain. The trend of soil texture evolution in different vertical zones at different altitudes shows a “V” pattern of change. The total variation of soil grain size indexes is more drastic at the highest and lowest elevations of Fanjing Mountain than in the middle, while the variation is relatively stable at the middle of the elevation. The evolution of soil texture at different levels of Fanjing Mountain is C > A > B, and the evolution of the C layer is due to the significant increase of sand particles, which may be related to the weathering of the soil parent material. Layers A and B, on the other hand, are due to an increase in clay, which may be related to the decomposition and uptake by soil microorganisms and plants. In summary, the different successional characteristics of soil texture with elevation and profile level are important factors driving the different natural successional status’ of the forests in Fanjing Mountain.