Storage and dynamics of carbon and nitrogen in soil after grazing exclusion in Leymus chinensis grasslands of northern China

Land-use change can lead to, changes in soil carbon and (C) 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, die 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, siginificant C and N storage on decade scales in the context of mitigating global climate change.