Abstract Overgrazing is a primary cause of grassland degradation, including the loss of soil carbon, but comprehensive analysis of the mechanism by which grazing affects soil organic carbon (SOC) is limited. To investigate this mechanism, we measured the contents of total soil organic carbon (TSOC) and active SOC fractions in grazed and ungrazed soil, and we examined the influence of grazing on soil microenvironments, soil carbon input, transformation and utilization, and soil respiration. The experiment was conducted in typical steppe in Inner Mongolia, China, under light, moderate, and heavy grazing plus a no-grazing control. Grazing changed the contents and stocks of the TSOC and active SOC fractions as well as the composition of the SOC. After three years, light and moderate grazing increased TSOC content by 3.44% and 5.43%, respectively, while heavy grazing decreased it by 4.30%. The changes in active SOC fractions were not uniform under different grazing intensities. All grazing intensities increased the stocks of microbial biomass carbon (MBC) and dissolved organic carbon (DOC) compared with the control, but their magnitudes did not rise with increased grazing intensity. Moderate grazing increased the stocks of potentially mineralizable carbon (PMC) and particulate organic carbon (POC), whereas light and heavy grazing decreased them; this may indicate likely long-term changes in SOC following changes in grazing intensity. Light grazing resulted in a larger C input to soil and faster transformation, more emission, and less accumulation of SOC. Moderate grazing led to a smaller C input to soil, and its transformation, utilization and emission rates were between those associated with light grazing and heavy grazing, and there was more accumulation. Heavy grazing resulted in the smallest C input, faster transformation and utilization, less change in emission, and less accumulation. Based on these results, moderate grazing is likely the most practical grazing intensity for the sustainable utilization of this grassland ecosystem to feed livestock. However, because this was a short-term study, the results did not reach significance, and long-term studies are needed.
Comprehensive analysis of grazing intensity impacts soil organic carbon: A case study in typical steppe of Inner Mongolia, China
Meng Zhang,Xiaobing Li,Hong Wang,Qi Huang
Published 2018 in Agriculture, Ecosystems & Environment. Applied Soil Ecology
ABSTRACT
PUBLICATION RECORD
- Publication year
2018
- Venue
Agriculture, Ecosystems & Environment. Applied Soil Ecology
- Publication date
2018-08-01
- Fields of study
Agricultural and Food Sciences, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
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CLAIMS
CONCEPTS
- active soil organic carbon fractions
The labile soil organic carbon pools measured to characterize readily cycling carbon in soil.
- dissolved organic carbon (doc)
The soluble organic carbon fraction present in soil solution.
Aliases: DOC
- grazing intensity
The level of livestock grazing applied in the experiment, ranging from no grazing to light, moderate, and heavy grazing treatments.
Aliases: grazing pressure
- microbial biomass carbon (mbc)
The carbon contained in the living microbial biomass in soil.
Aliases: MBC
- moderate grazing
The intermediate grazing treatment between light and heavy grazing used in the experiment.
Aliases: moderate grazing treatment
- particulate organic carbon (poc)
The organic carbon fraction associated with particulate soil organic matter.
Aliases: POC
- potentially mineralizable carbon (pmc)
The soil carbon pool that can be mineralized by microbes under incubation.
Aliases: PMC
- total soil organic carbon (tsoc)
The total organic carbon content or stock measured in the soil.
Aliases: TSOC
- typical steppe of inner mongolia, china
The grassland study site in Inner Mongolia, China, where the grazing experiment was conducted.
Aliases: Inner Mongolia typical steppe
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