Soil biology and carbon sequestration in grasslands

摘要: Grassland soils are recognized for their capacity to sequester, or store, soil carbon (C), which is due to their high primary productivity, the accumulation of above-and belowground litter and plant rhizodeposits, and the stability of by-products produced by soil biological processes during decomposition (Amundson 2001; Conant et al. 2001; von Lützow et al. 2006). By storing soil C, grasslands provide key ecosystem services such as mitigating greenhouse gas emissions, enhancing nutrient cycling and retention, and promoting plant productivity (Woods 1989; Burke et al. 1989; Bauer and Black 1994; Sparling et al. 2006). Organic C inputs to soil largely consist of plant materials. Soil biota mediate the plant-soil transfers, which retain C and other nutrients in soil and build soil organic matter (SOM). The compositions of soil microbial and faunal communities, and their interactions, are increasingly recognized as important for the stabilization of soil C from plant and microbial residues (Guggenberger et al. 1999; Denef et al. 2001). Changes in microbial community composition are often linked to changes in nutrient transformations in soil (Carney et al. 2004; Wardle et al. 2004), even though direct relationships between specific taxa, eg, identity and numbers, and process rates have only rarely been identified (Okano et al. 2004; Wardle et al. 2006; Six et al. 2006). Human activities have profound effects on soil biological processes and soil C sequestration, mainly through conversion of grasslands to cultivated agriculture, and vice versa. When grasslands are tilled for crop production, a large proportion of the soil C is lost since C in previously protected soil …