Vegetation restoration alleviated the soil surface organic carbon redistribution in the hillslope scale on the Loess Plateau, China

ABSTRACT 

Redistribution of soil organic carbon (SOC) in response to soil erosion along slopes plays an important role in understanding the mechanisms of SOC’s spatial distribution and turnover. Consequently, SOC redistribution has been considered in many conceptual or mathematical models of soil carbon stability and storage. Vegetation restoration has been identified as an effective method to alleviate soil erosion on the Loess Plateau, however, little research has addressed vegetation restoration’s effect on the SOC redistribution processes, particularly SOC’s spatial distribution and stability. This study quantified the SOC stock and pool distribution on slopes along geomorphic gradients in naturally regenerating forests (NF) and an artificial black locust plantation (BP), and used a corn field as a control (CK). The following results were as follows: (1) Vegetation restoration, particularly NF, slowed the migration of SOC and reduced the heterogeneity of its distribution effectively. The topsoil SOC ratios of the sedimentary area to the stable area were 109%, 143%, and 210% for NF, the BP and CK, respectively; (2) Vegetation restoration decreased the loss of labile organic carbon by alleviating the loss of dissolved organic carbon (DOC) and easily oxidized organic carbon (EOC). The DOC/SOC in the BP and NF increased significantly, and were 13.14 and 17.57 times higher, respectively, than in the CK (p < 0.05), while the EOC/SOC in the BP and NF was slightly higher than in the CK. (3) A relevant schematic diagram of SOC cycle patterns and redistribution along the Loess slope was drawn under vegetation restoration. These results suggest that vegetation restoration in the Loess slope effectively alleviated the redistribution and spatial heterogeneity of SOC through reducing soil erosion. Thus, the effects of vegetation restoration on SOC redistribution should be pay more attention in regional carbon storage estimation, especially in the Loess gully regions.

Keywords: Vegetation Restoration, Soil Organic Carbon Redistribution, Loess Slope, Soil Erosion, Soil Organic Carbon Stability