title: Ecosystem carbon and nitrogen accumulation after grazing exclusion in semiarid grassland.
abstract: The grazing exclusion in degraded grassland has been extensively used to prevent the loss of grassland resources and to improve grassland services. The effects of grazing exclusion on C and N balance, however, have not been well addressed but are essential for assessing grassland C sinks, the sustainable use of grassland resources and the support of grassland services. To understand the response of ecosystem C and N to grazing exclusion in semiarid grassland, we determined the C and N in litter, aboveground biomass, roots and soils from ungrazed grassland fenced at different times in northwest China. Our results showed that the aboveground biomass, root biomass and plant litter were 70-92%, 56-151% and 59-141% higher, respectively, in grazer excluded grassland than in grazed grassland. Grazing exclusion significantly increased C and N stored in plant biomass and litter and increased the concentrations and stocks of C and N in soils. Grazing exclusion thus significantly increased the C and N stored in grassland ecosystems. The increase in C and N stored in soil contributed to more than 95% and 97% of the increases in ecosystem C and N storage. The highest C and N stocks in ecosystems were observed in 17-year grazer excluded grassland. The results from this study indicate that grazing exclusion has the potential to increase C and N storage in degraded semiarid grassland and that the recovery of ecosystem C and N was mainly due to the accumulation of C and N in soils.
authors: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling, China.
authors: Liping
authors: L
authors: Qiu
authors: Xiaorong
authors: X
authors: Wei
authors: Xingchang
authors: X
authors: Zhang
authors: Jimin
authors: J
authors: Cheng
mesh_terms: D000818:Animals; D002244:Carbon / Q000378:metabolism*; D057965:Carbon Sequestration / Q000502:physiology*; D002681:China; D003247:Conservation of Natural Resources / Q000379:methods / Q000706:statistics & numerical data*; D017753:Ecosystem; D060434:Herbivory / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D035261:Plant Components, Aerial / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
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