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对三峡库区典型林分林地土壤有机碳(SOC)含量特征及对土壤物理性质、土壤结构和土壤养分效应进行研究,以期为三峡库区生态环境建设提供依据。结果表明:SOC含量表现为表层(A层)土壤(12.06～45.18g/kg)明显大于下层土壤,大一个数量级。从土壤表层到底层,SOC含量呈明显下降趋势。由相同立地条件的灌木林改造而来的农地土壤(改造年限8a)各层土壤SOC含量都有所降低,土壤表层SOC含量降低了10%,土壤平均有机碳含量降到为灌木林地的66%。三峡库区SOC含量与土壤物理性质直接相关,SOC含量与土壤容重和土壤毛管孔隙度存在最为明显的线性关系(R2=0.83,0.83,n=19,p<0.01)。土壤有机碳直接参与了土团聚体的形成,SOC含量与土壤团聚度和土壤团聚状况均有较好的相关关系(R2=0.62,0.76,n=19,p<0.01)。各林地土壤中氮元素含量最高,速效氮含量约为速效磷的6倍,为速效钾的2.5倍。SOC与土壤主要营养元素(N,P,K)关系中,对N元素作用最明显,特别是速效氮(R2=0.66,n=19,p<0.01),对磷的矿化起主要作用,与钾元素关系不明显。土壤有机碳是决定N和P矿化的主导因子,从土壤表层到底层C/N比值呈下降趋势,C/P值约为C/N值的6倍。阳离子交换量(CEC)与土壤团聚度之间有明显的相关关系(R2=0.49,n=19,p<0.01)。SOC对CEC的作用主要通过改变土壤结构而实现。
The soil organic carbon (SOC) content, soil physical properties, soil structure and soil nutrient effect of typical forest in the Three Gorges Reservoir Area were studied in order to provide the basis for the ecological environment construction in the Three Gorges Reservoir Area. The results showed that the content of SOC in surface layer (A layer) soil (12.06 ~ 45.18g / kg) was obviously larger than that of the underlying soil, an order of magnitude larger. From the soil surface to the bottom, SOC content showed a clear downward trend. The soil SOC content of all layers of farmland converted from shrub land under the same site conditions (rehabilitated years 8a) decreased, the SOC content of soil surface decreased by 10%, and the average soil organic carbon content decreased to 66 %. The SOC content in the Three Gorges Reservoir area is directly related to the physical properties of soil. The SOC content has the most obvious linear relationship with soil bulk density and soil capillary porosity (R2 = 0.83, 0.83, n = 19, p <0.01). Soil organic carbon was directly involved in the formation of soil aggregates. SOC content had a good correlation with soil aggregates and soil aggregates (R2 = 0.62, 0.76, n = 19, p <0.01). The content of nitrogen in soil of each forest was the highest, available nitrogen was about 6 times of that of available phosphorus and 2.5 times of available potassium. The relationship between SOC and N, P and K in soil was the most obvious for N element, especially available nitrogen (R2 = 0.66, n = 19, p <0.01), which played a major role in phosphorus mineralization. And the relationship between potassium is not obvious. Soil organic carbon is the dominant factor that determines the mineralization of N and P, and the C / N ratio decreases from the surface to the bottom. The C / P value is about 6 times of the C / N value. There was a significant correlation between CEC and soil aggregate (R2 = 0.49, n = 19, p <0.01). The effect of SOC on CEC is mainly achieved by changing the soil structure.