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 (WR0.25), 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 WR0.25, 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 WR0.25, MWD, and GMD, but a negative correlation with D and PAD. 4) Soil detachment rate declined exponentially with the increases of WR0.25. 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.
不同植被恢复模式下的土壤具有不同的团聚体特征和抗侵蚀性能,然而,目前尚不清楚植被恢复模式如何影响团聚体特征和土壤分离速率。本研究以福建省长汀县马尾松低效林地5种植被恢复模式(封禁模式,M1;风水林模式,M2;全坡面播草模式,M3;低效林改造模式,M4;条沟草灌带模式,M5)为对象,以侵蚀裸地(CK)为对照,分析不同恢复模式下土壤团聚体和土壤分离速率的变化特征及其影响因素。结果表明: 1)与CK相比,各植被恢复模式下土壤分离速率显著降低了84.7%~98.6%,有机质显著提升了140.2%~869.4%。2)在5种植被恢复模式中,M1的团聚体稳定性最差,其水稳性大团聚体含量(WR0.25)、团聚体平均重量直径(MWD)、几何平均直径(GMD)显著低于M2、M3、M5模式,分形维数(D)、水稳性团聚体破坏率(PAD)显著高于M2、M3、M5模式。而M5的土壤分离速率仅为CK的1.4%,土壤团聚体稳定性表现最佳,其WR0.25、MWD、GMD显著高于其他模式,D显著低于其他模式。3)土壤有机质与土壤团聚体稳定性密切相关,其中,土壤有机质与WR0.25、MWD和GMD呈正相关,与D和PAD呈负相关。4)土壤分离速率随WR0.25上升呈指数函数下降。综上,植被恢复导致的土壤有机质含量提升对水稳性大团聚体形成、土壤分离速率降低起到关键作用,条沟草灌带模式是南方红壤区值得推广的植被恢复模式。.
Keywords: red soil; soil aggregate; soil detachment rate; vegetation restoration mode.