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通过密度分组和超声波技术将每个土样分为3个组份:自由组份、闭合组份和重组,分别分析每个组份的有机碳质量分数.闭合组份和重组中的有机碳为受物理保护的有机碳.结果表明:在整个土壤剖面上各组份有机碳的数量表现为重组有机碳>自由轻组>闭合轻组,这就表明土壤中大部分有机碳是受物理保护的.各组份有机碳均表现为在0～40 cm深度迅速递减,40～80 cm深度相对稳定.随深度的增加,轻组中有机碳递减速率比重组和闭合组份中有机碳的递减显著.如0～10 cm深度轻组有机碳质量分数为6.672×10~(-6),但在60～80 cm深度轻组有机碳质量分数仅为0.260×10~(-6);0～10 cm深度重组有机碳质量分数为17.228×10~(-6),在60～80 cm深度重组有机碳质量分数为6.563×10~(-6).子午岭森林灰褐土保护有机碳的能力是有限的,通过曲线拟合得出在该地区每1000 g土壤中受物理保护的有机碳不会超过23.64 g.表层以下大部分土壤颗粒远未达到饱和,如果有更多的有机碳可利用,这部分土壤具有较大的碳汇潜能.
Each soil sample was divided into three components by density grouping and ultrasonic technique: free component, closed component and reorganization, respectively analyzing the organic carbon content of each component.The organic components in the closed components and reorganization were The results showed that the amount of organic carbon in each component of the whole soil profile showed as follows: recombinant organic carbon> free light group> closed light group, indicating that most of the organic carbon in the soil is physically protected .Compared with the control group, the organic carbon in all the components decreased rapidly at the depth of 0-40 cm and the depth was relatively stable at 40-80 cm.With the increase of the depth, the decrease rate of organic carbon in the light fraction was significantly lower than that in the heavy fraction and the closed fraction For 0 ~ 10 cm depth, the mass fraction of organic carbon was 6.672 × 10 ~ (-6), but the mass fraction of organic carbon was only 0.260 × 10 ~ (-6) in the depth of 60 ~ 80 cm; cm, the mass fraction of reorganized organic carbon was 17.228 × 10 -6, and the mass fraction of reorganized organic carbon was 6.563 × 10 -6 at depth of 60-80 cm. The ability of Zihua Mountain forest to protect organic carbon was Limited, curve fit shows that the physically protected organic carbon per 1000 g of soils in the area does not exceed 23.64 g. Most of the soil particles below the surface layer are far from saturated. If more organic carbon is available, this part of soil has greater carbon sink potential.