土壤的结构和功能(2018必威体育精装版).pptx

土壤的结构与功能（2018必威体育精装版总结）2018年11月30日土壤固碳过程与机理Intra-aggregate physical protection is the leading driver of C. One of the mechanisms of organic matter protection is heterogeneity of soil microenvironment which limits the access of decomposing microorganisms and their enzymes to organic material (Schmidt et al., 2011).Spatial arrangement and size distribution of intra-aggregate pores play an important role in this process. This require to examine relationships between intra-aggregate pores measured using X-ray computed micro-tomography images and C (i.e. concentration, spatial distribution, etc).Soil C microbesSoil pore The μ-CT tools are well suited for providing information on characteristics of soil physical micro-environments (soil pores). C sequestration capacity Total C concentrations in interior and exterior sections of aggregatesFractions of 37.5-67.5 ?m and 127.5 ?m pores in the aggregateStrong et al. (2004) reported faster decomposition of plant residues in 15-60 ?m pores, but lower C decomposition in soils with higher percent of very small and very large pores. Strong et al. (2004) reported a negative correlation between total C and 15-60 ?m pores as well as greater microbial activity in such pores.Ananyeva et al. (2013) found that abundance of 40–70 μm pores was negatively correlated with levels of organic C in the soil macro-aggregates. The result suggested that intraaggregate areas with greater presence of such pores were poorly protecting it. Kravchenko et al. (2015) noted positive association between the presence of atmosphere-connected pores of 30–60 μm size range and the amount of CO2 emitted from the soil macro-aggregates during incubation, again signifying the role of these pores in enhancing organic matter decomposition. It should be noted that not only pore size but also whether or not they were connected to the atmosphere appeared to matter in organic C decomposition. Based on visual observations of the X-ray μ-CT images such pores were primarily of no