Ecosystem Carbon and Nitrogen Accumulation after Grazing Exclusion in Semiarid Grassland

• Published in: PloS one Vol. 8; no. 1; p. e55433
• Main Authors: Qiu, Liping, Wei, Xiaorong, Zhang, Xingchang, Cheng, Jimin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.01.2013; Public Library of Science (PLoS)
• Subjects: Accumulation; Animals; Biology; Biomass; Carbon; Carbon - metabolism; Carbon Sequestration - physiology; China; Conservation of Natural Resources - methods; Conservation of Natural Resources - statistics & numerical data; Earth Sciences; Ecosystem; Ecosystem recovery; Ecosystems; Farming; Grasslands; Grazing; Herbivores; Herbivory - physiology; Laboratories; Litter; Mineralization; Nitrogen; Nitrogen - metabolism; Nitrous oxide; Plant biomass; Plant Components, Aerial - metabolism; Plant Roots - metabolism; Poaceae - metabolism; Precipitation; Soil - chemistry; Soil erosion; Storage; Sustainable development; Sustainable use; Topography; China; Loess Plateau
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0055433

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.