中宁枸杞土壤碳组分分布特征及其空间异质性

以中宁枸杞林地为研究区,采用100 m×100 m网格方式采集耕层土壤样品(0~20 cm)119个,利用经典统计和地统计相结合的方法对土壤碳组分空间变异性进行研究.经典统计表明土壤总碳、无机碳、有机碳、活性有机碳、中活性有机碳和高活性有机碳的平均含量分别为28.74、18.72、10.09、1.81、1.48和0.73 g·kg-1.总碳、无机碳变异系数分别为7.69%和9.13%,属弱变异.有机碳、活性有机碳、中活性有机碳和高活性有机碳变异系数介于14.77%~52.05%,呈中等变异性.地统计结果表明总碳和有机碳的块金值和基台值的比值分别为48.99%和34.35%,在空间上呈中等相关性.无机碳、活性有机碳、中活性有机碳和高活性有机碳块金值和基台值的比值分别为8.17%、0.25%、12.18%和0.08%,均小于25%,在空间上呈强烈的相关性.根据普通克里格插值图可以看出,土壤总碳、有机碳、中活性有机碳与高活性有机碳分布大致相似,从东南向西北方向逐渐升高.无机碳和活性有机碳在空间上呈现不规则岛状分布.

Spatial Heterogeneity of Soil Carbon and its Fractions in the Wolfberry Field of Zhongning County

It is important to accurately assess the regional spatial distribution and variation of soil carbon and its fractions due to its great significance in soil carbon cycling and soil quality. The objectives of this study were to investigate the spatial variability of soil carbon and its fractions using classical and geostatistical statistics. Topsoil samples (0-20 cm) from 119 sites in Wolfberry Field were collected from a grid of 100 m×100 m in Zhongning County. The GS+7.0 software was used to fit a semivariance model to determine the optimal theoretical model and parameters. The spatial distribution characteristics of soil carbon and its fractions were studied by ordinary kriging. The classical statistical analyses showed that the average concentrations of total carbon, inorganic carbon, organic carbon, active organic carbon, medium active organic carbon, and high active organic carbon were 28.74, 18.72, 10.09, 1.81, 1.48, and 0.73 g·kg^-1, respectively. The variation coefficient of total carbon and inorganic carbon were 7.69% and 9.13%, indicating a strong variation, while the other soil carbon fractions showed moderate variation with the coefficients of variations ranging from 14.77%-52.05%. The geostatistical analyses revealed that the semivariogram of organic carbon was best fit by the spherical model, while the other five kinds of carbon fractions were best fit by the exponential model. The nugget coefficients of total carbon and organic carbon were 48.99% and 34.35%, which demonstrated moderate spatial dependence. The nugget coefficients of inorganic carbon, active organic carbon, medium active organic carbon, and high active organic carbon were 8.17%, 0.25%, 12.18%, and 0.08%, which demonstrated strong spatial dependence. The ordinary kriging interpolation map indicated that the spatial distribution patterns were similar for total carbon, organic carbon, medium active organic carbon, and high active organic carbon, which increased from southeast to northwest. Inorganic carbon and active organic carbon presented an irregular plaque distribution in the study area. Spatial interpolation maps could provide useful information for environmental management and the sustainable use of land resources in this region.