Track 2-2-2: Plant-Animal Interactions, Grazing Behaviour and Plant Quarantine

Description

Carbon sequestration is one of the most important ecological function of the grassland. Soils contain more carbon than in vegetation in the form of soil organic matter (SOM). But grassland soils are vulnerable to disturbances caused by human activities. Grazing may result in various disturbances to both soil and vegetation under different grazing intensities (Bai et al., 2012). Grazing led to the shifts in amount and composition of soil organic matter. In previous studies, the chemical methods were used to separate soil into the different pools according to the stability of SOM (Carvalho Leite et al., 2004), but they cannot be convictive for their chemical destruction upon the SOM structure. In this study, we use more credible fractionating method to separate stable part of the SOM based on the dry sieving and winnowing (Kirkby et al., 2011).

Stable carbon fraction has two origins: microbial debris and recalcitrant plant materials (Lehmann et al., 2007). Evidences have showed that soil microbial community alters metabolic rates by changing its composition adjust to stoichiometry of substrates. We hypothesize that carbon content stable fraction SOM in the surface soils would decline as the intensity increasing, but the stoichiometry of carbon and nutrients (N and P) would remain constant. We also predict that the relative importance in carbon sequestration of microbial groups would change due to the soil environmental alteration. The objectives of the study is to evaluate the effects of grazing intensity (GI) on carbon in more stabilized SOM and on soil microbial community structure in steppe.

Share

COinS
 

Changes in Stable Fraction of Soil Organic Carbon and Microbial Structure in Response of Grazing Intensity

Carbon sequestration is one of the most important ecological function of the grassland. Soils contain more carbon than in vegetation in the form of soil organic matter (SOM). But grassland soils are vulnerable to disturbances caused by human activities. Grazing may result in various disturbances to both soil and vegetation under different grazing intensities (Bai et al., 2012). Grazing led to the shifts in amount and composition of soil organic matter. In previous studies, the chemical methods were used to separate soil into the different pools according to the stability of SOM (Carvalho Leite et al., 2004), but they cannot be convictive for their chemical destruction upon the SOM structure. In this study, we use more credible fractionating method to separate stable part of the SOM based on the dry sieving and winnowing (Kirkby et al., 2011).

Stable carbon fraction has two origins: microbial debris and recalcitrant plant materials (Lehmann et al., 2007). Evidences have showed that soil microbial community alters metabolic rates by changing its composition adjust to stoichiometry of substrates. We hypothesize that carbon content stable fraction SOM in the surface soils would decline as the intensity increasing, but the stoichiometry of carbon and nutrients (N and P) would remain constant. We also predict that the relative importance in carbon sequestration of microbial groups would change due to the soil environmental alteration. The objectives of the study is to evaluate the effects of grazing intensity (GI) on carbon in more stabilized SOM and on soil microbial community structure in steppe.