Effects of grazing on the allocation of mass of soil aggregates and aggregate-associated organic carbon in an alpine meadow

Abstract

Soil aggregation is closely related to the soil organic carbon sequestration, both of which plays an important role in the stability of the soil carbon pool. However, the results of the impact of yak grazing intensity on the soil carbon process in alpine meadows have been unclear. With the marsh meadow as the research object in the Gahai wetland of the east Qinghai-Tibet Plateau, we analyzed the influence of different grazing intensities on the allocation of mass, stability and aggregate-associated organic carbon content of aggregates in the surface soil (0-20cm) of pasture by the Le Bissonnais method. The results showed that the mass of aggregates in the particle size class of > 0.2-mm was the highest among the pastures with different grazing intensities. Compared with the no grazing grassland, light grazing promoted the formation of macro aggregates in the particle size class of > 1-mm and improved the stability of soil aggregates. The degree of soil agglomerations and stability of aggregates decreased, and the macro aggregates gradually transformed into micro aggregates (< 0.05-mm class) in moderately and heavily grazed pastures. The > 2-mm and < 0.05-mm classes of particle size had a strong fixation effect on organic carbon. Light grazing promoted the accumulation of organic carbon in this particle size aggregate, and moderate and heavy grazing accelerated the decomposition of organic carbon. There was no significant difference in organic carbon in other particle size aggregates among different grasslands (P > 0.05). This result shows that light grazing, which is a reasonable yak grazing intensity in the study area, is conducive to the formation of a good soil structure in the area and improves the soil carbon sequestration capacity.

Effect of Grazing Exclusion and Rotational Grazing on Soil Aggregate Stability in Typical Grasslands in Inner Mongolia, China

“…As a result, medium and high grazing offset the increased aggregates stimulated by grazing. Our result is consistent with Wang et al (2020) who also found light grazing promoted the formation of coarse aggregates and higher grazing intensity caused the disintegration of soil aggregates. Our results also showed that coarse aggregate stability was lower than fine aggregate stability (Figures 3B,E, Figures 4B,E).…”

Changes in the Quality of Vegetation Cover and Soil of Pastures in Semi-Deserts of West Kazakhstan, Depending on the Grazing Methods

“…Studies of the impact of animal trampling on haphazardly used pastures have shown that the harmful effects of animal grazing on volume density and aggregate stability tend to become more serious as the number of animals grazing per unit area increases [Poffenbarger, 2010;Wang et al, 2020]. We found an increase in soil compaction of up to 13.11% with an increase in grazing intensity compared to no grazing [Neff et al, 2005].…”

Effects of Betula platyphylla invasion in North China on soil aggregate stability, soil organic carbon and active carbon composition of larch plantation

“…Soil microorganisms are the living components in the soil, which are extremely sensitive to various changes in the soil environment and can fully re ect the ecological functions of microbial communities. Microbial biomass is not only an important source of soil nutrients, but also an important carrier for soil nutrient xation (Wang et al, 2020). Soil MBC is an active component of the soil carbon pool and plays an important role in the soil carbon cycle (Lihua et al, 2010).…”