黄土高塬沟壑区植被恢复对不同地貌部位 土壤可蚀性的影响.

Vegetation restoration has returned a large number of steep slope farmlands to forests and grasslands, and effectively controlled soil erosion in the Loess Plateau. In the loesstableland and gully region of the Loess Plateau, loess-tableland, hill-slope and gully-slope are widely distributed. Geomorphological location and land use may lead to differences in soil properties and vegetation root systems, and thus affect soil erodibility. However, few studies have been conducted to explore the impact of vegetation restoration at different geomorphological locations on soil erodibility, and the relationships between soil erodibility and influencing factors. This study was carried out in the Nanxiaogou watershed in the loesstableland and gully region of the Loess Plateau. The undisturbed topsoil (0-20 cm) of farmland, grassland, shrub land and woodland was sampled on loess-tableland, hill-slope and gully-slope (no farmland on gully-slope). The comprehensive soil erodibility index (CSEI) was obtained by weighted sum method. The results indicated that: (1) The significant difference in CSEI was found among different geomorphological locations. The CSEI of gully- slope was 8.1% and 77.7% higher than those of hill- slope and loess- tableland, respectively. (2) As for the loesstableland, the CSEI of grassland, shrub land and woodland decreased by 21.1%, 29.2% and 28.8%, respectively compared with that of farmland. For the hill- slope and gully- slopes, the CSEI of woodland was lower than that of other land use types. (3) The CSEI had significantly negative correlations with clay content, sand content, soil capillary porosity, root weight density, root mean diameter, root length density and root surface area density, but significantly positive correlations with silt content and soil bulk density. Multivariate linear stepwise regression indicates that silt content, root mean diameter and soil bulk density are the most important factors influencing CSEI, among which silt content has the greatest direct influence on CSEI, while root mean diameter exerts negative influence on CSEI through direct or indirect effects. This study suggests that shrubs should be the preferred vegetation for vegetation restoration on the loess- tableland. Revegetation with arbor as dominant community may be more effective in controlling soil and water loss on hill-slope and gully-slope. [ABSTRACT FROM AUTHOR]