title: Storage and dynamics of carbon and nitrogen in soil after grazing exclusion in Leymus chinensis grasslands of northern China.
abstract: Land-use change can lead to changes in soil carbon (C) and nitrogen (N) storage. This study aimed to determine the impact of long-term grazing exclusion (GE) on soil organic C and total N (TN) storage in the Leymus chinensis grasslands of northern China and to estimate the dynamics of recovery after GE. We investigated the aboveground biomass and soil organic C and TN storage in six contiguous plots along a GE chronosequence comprising free grazing, 3-yr GE, 8-yr GE, 20-yr GE, 24-yr GE, and 28-yr GE. Grazing exclusion for two decades increased the soil C and N storage by 35.7 and 14.6%, respectively, in the 0- to 40-cm soil layer. The aboveground net primary productivity and soil C and N storage were the highest with 24-yr GE and the lowest with free grazing. The storage increased logarithmically with the duration of GE; after an initial rapid increase after the introduction of GE, the storage attained equilibrium after 20 yr. A logarithmic regression analysis revealed 86.8 and 87.1% variation in the soil C storage and 74.2 and 80.7% variation in the soil N storage in the 0- to 10-cm and 0- to 40-cm soil layers, respectively. Based on these results, we suggest that two decades of GE would restore the L. chinensis grasslands from being lightly degraded to a stable productive condition with good soil C and N storage capacity. Our results demonstrated that by implementing GE, the temperate grasslands of northern China could facilitate significant C and N storage on decade scales in the context of mitigating global climate change.
authors.affiliation: Key Lab. of Vegetation and Environmental Change, Inst. of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.forename: N
authors.initials: N
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Han
mesh_terms: D000383:Agriculture / Q000379:methods*; D002244:Carbon / Q000032:analysis*; D002681:China; D009584:Nitrogen / Q000032:analysis*; D006109:Poaceae; D012987:Soil / Q000032:analysis*
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen