Response of soil moisture characteristics to litter and fine root return from vegetation restored on eroded soils in the subtropical China
Soil erosion has been a serious problem in the subtropical China, negatively impacting the restoration and stabilization of vegetation and potentially reducing biodiversity. Vegetation restoration on eroded soils may improve soil water status through increasing soil organic carbon (SOC) due to the increased litter and fine root input. However, little is known about the direct roles of litter and fine root in soil water status, particularly in deep soils. Therefore, we measured soil water content (SWC) and organic carbon of litter and fine roots in different soil layers (0~20, 20~40, 40~60, 60~80cm) in four vegetation types typically restored on eroded soils. The four vegetation types are: Citrus reticulata Banco forest (CB), forbidden forest (FF), Schima superba-Pinus massonianamixed forest (SP) and broad-leaved forest (BL). We measured the SWC by pressure membrane method, and sampled litter and fine root by quadrat investigation and intact-core method, respectively.
The results show that SWC in CB decreased with increasing soil depth and had greater reduction than other vegetation types (i.e., FF, SP, BL). SWC in the bottom soil layer (60~80cm) varied differently among the four vegetation types, compared with the topsoil layer (0~10cm). The reductions in SWC in BL were smallest among the four vegetation types, irrespective of soil layers and water suction conditions. The total litter mass and litter organic carbon varied among vegetation types, with SP> BL > FF > CB. However, the fine root and its carbon showed different trends, with CB> FF > BL > SP. The carbon return of broad leaf and SWC in BL were larger than those in SP. The fine root mass in the 0~20cm soil layer in CB and BL was greater than those in FF and SP. In summary, our results indicate that the carbon return from fine roots had greater impacts on SWC when vegetation was restored on eroded soils in the subtropical China.