Grazing improves C and N cycling in the Northern Great Plains: a meta-analysis.
Grazing potentially alters grassland ecosystem carbon (C) and nitrogen (N) storage and cycles, however, the overall direction and magnitude of such alterations are poorly understood on the Northern Great Plains (NGP). By synthesizing data from multiple studies on grazed NGP ecosystems, we quantified the response of 30 variables to C and N pools and fluxes to grazing using a comprehensive meta-analysis method. Results showed that grazing enhanced soil C (5.2 ± 4.6% relative) and N (11.3 ± 9.1%) pools in the top layer, stimulated litter decomposition (26.8 ± 18.4%) and soil N mineralization (22.3 ± 18.4%) and enhanced soil NH4(+) (51.5 ± 42.9%) and NO3(-) (47.5 ± 20.7%) concentrations. Our results indicate that the NGP grasslands have sequestered C and N in the past 70 to 80 years, recovering C and N lost during a period of widespread grassland deterioration that occurred in the first half of the 20(th) century. Sustainable grazing management employed after this deterioration has acted as a critical factor for C and N amelioration of degraded NGP grasslands and about 5.84 Mg C ha(-1) CO2-equivalent of anthropogenic CO2 emissions has been offset by these grassland soils.
Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa K1A0C6, Canada.
Xiaoyu
X
Wang
Swift-Current Research and Development Centre, A griculture and Agri-Food Canada, Swift Current S9H3X2, Canada.
Brian G
BG
McConkey
Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa K1A0C6, Canada.
A J
AJ
VandenBygaart
Swift-Current Research and Development Centre, A griculture and Agri-Food Canada, Swift Current S9H3X2, Canada.
Jianling
J
Fan
Swift-Current Research and Development Centre, A griculture and Agri-Food Canada, Swift Current S9H3X2, Canada.
Alan
A
Iwaasa
Swift-Current Research and Development Centre, A griculture and Agri-Food Canada, Swift Current S9H3X2, Canada.
Mike
M
Schellenberg
D000383:Agriculture; D000818:Animals; D057486:Carbon Cycle; D003247:Conservation of Natural Resources; D065948:Grassland; D060434:Herbivory; D058458:Nitrogen Cycle; D014481:United States