Differences in soil aggregates characteristics and soil detachment rate in degraded red soil among different vegetation restoration modes.

Soil aggregate traits and anti-erosion ability vary across different vegetation restoration modes. However, it remained unclear how vegetation restoration modes affect soil aggregate characteristics and soil detachment rate. We examined the variations in soil aggregate and soil detachment rate as well as the influencing factors in the low growth efficiency Pinus massoniana forests of Changting County, Fujian Province under five restoration modes, i.e, closure management (M₁), geomantic forest (M₂), planting grass on the whole slope (M₃), low growth efficiency forest transformation (M₄), and the strip grass-shrub belt mode (M₅), with the eroded bare land as the control (CK). The results showed that: 1) Soil detachment rate was significantly decreased by 84.7% to 98.6% under all vegetation restoration modes, while soil organic matter content was significantly increased by 140.2% to 869.4%. 2) The aggregate stability in M₁ was the lowest among the five vegetation restoration modes, and water stable macroaggregates (WR_0.25), mean weight diameter (MWD), geometric mean diameter (GMD) were significantly lower in M₁ mode than those in M₂, M₃, and M₅, while the fractal dimension (D) and the water-stable aggregate destruction rate (PAD) were significantly higher than the M₂, M₃, and M₅. Soil detachment rate of M₅ was 1.4% of CK, with the highest soil aggregate stability. The WR_0.25, MWD, and GMD in M₅ were significantly higher, while D was significantly lower than that in other modes. 3) Soil organic matter content was closely related with aggregate stability. Soil organic matter content had a positive correlation with WR_0.25, MWD, and GMD, but a negative correlation with D and PAD. 4) Soil detachment rate declined exponentially with the increases of WR_0.25. In summary, the increases in soil organic matter content induced by vegetation restoration played a key role in the formation of water-stable macroaggregates and the reduction in soil detachment rate. We recommend the strip grass-shrub belt mode for vegetation restoration in the red soil regions of southern China.