Effects of Different Vegetation Restoration Measures on the Disintegration Characteristics of Eroded Degraded Land of Pinus massoniana in Red Soil Region

[Objective] To investigate the characteristics of soil disintegration under different vegetation restoration measures in degraded land of Pinus massoniana, compare the improvement of soil disintegration in severely degraded P. massoniana land in granite red soil area of Southern China by different vegetation restoration measures, and reveal the interactions between the influencing factors of soil disintegration in granite red soil area in Southern China. [Methods] In this study, a severely degraded land of P. massoniana in Changting County was selected as the research area, and a degraded land of P. massoniana was used as the control group (CK). Three vegetation restoration measures, including closure management (E1), whole slope sowing grass (E2) and tree-shrub-grass ditch model (E3), were set as the experimental groups. Correlation analysis, principal component analysis and path analysis were used to study the disintegration of surface soil in four plots. [Results] (1) There were significant differences in soil anti-erodibility under each measure. Compared with CK, the soil disintegration coefficient of E1, E2 and E3 measures decreased by 16.3%, 52.5% and 67.2%, respectively. The tree-shrub-grass furrow model (E3) was more suitable for the treatment of severely degraded P. massoniana land. (2) Soil organic carbon content, total phosphorus content, available phosphorus content, total potassium content, available potassium content, water content and aggregate characteristics were the main influencing factors of soil disintegration. (3) Among various factors affecting soil disintegration, soil geometric mean diameter (GMD) was the main direct influencing factor and played a dominant controlling role. [Conclusion] The size of soil disintegration characteristics under different vegetation restoration measures follows the order of CK > E1 > E2 > E3. The soil disintegration characteristics can be maintained at a low level by adopting the tree-shrub-grass furrow management measure. This measure is more effective for soil and water loss control in severely degraded P. massoniana forest in granite red soil area. Soil geometric mean diameter (GMD) is a direct control factor affecting soil disintegration characteristics, and can be used as a preferred index to evaluate soil disintegration characteristics.