Land-use changes driven by 'Grain for Green' program reduced carbon loss induced by soil erosion on the Loess Plateau of China

摘要

Vegetation restoration on degraded lands has been encouraged worldwide due to its ecological services and function of controlling soil erosion and improving carbon (C) stocks in terrestrial ecosystems. Although the processes of runoff and sediment detachment and transport are well recognized, the effects of vegetation restoration on organic C loss through soil erosion are not fully understood within a given landscape. This study conducted a synthesis from 66 sites to evaluate the effects of vegetation restoration on annual C loss induced by soil erosion across the key areas of the 'Grain for Green' Program (GGP) in the Loess Plateau, China. The results showed that vegetation restoration has significantly reduced the annual C loss in sediment and from runoff. Since 2000, a total of 8.6 x 10(6) ha degraded land has been converted to forests, shrubs and grasslands under the GGP, which has reduced runoff by 1.5 x 10(9) m(3) and is associated with 7.3 x 10(3) Mg C; furthermore, lost sediment has reduced by 348.7 Tg, which is associated with 1.8 Tg C per year, across the Loess Plateau. In the zone with a mean annual precipitation (MAP) 550 mm, the degraded lands that have been converted to grasslands and shrubs have reduced more soil and water losses than have the lands that have been converted to forests; additionally, in the zone with a MAP 550 mm, the degraded lands that have been converted to forests have less soil erosion than do the lands that have been converted to grasslands and shrubs. Moreover, C loss induced by soil erosion was mainly affected by plant cover, soil porosity, slope, land-use change, and rainfall intensity on the Loess Plateau. This study suggests that optimal vegetation restoration measures should be adopted based on local conditions to reduce C loss induced by soil erosion.