露天煤矿复垦区土壤有机碳含量变化归因解析

Attribution of soil organic carbon content change in reclamation area of opencast coal mine

土壤有机碳(SOC)是评价土壤质量变化的关键指标,辨析煤矿复垦区SOC演变过程、影响因素及驱动机制,对指导矿区复垦工作开展具有重要意义。文中以山西平朔露天煤矿复垦平盘土壤为研究对象,以空间序列替代时间序列,定量解析复垦SOC及剖面分布对复垦年限和复垦方式的响应。结果显示:复垦平盘SOC含量在0.82~16.11g·kg^(-1)之间,均值为3.53 g·kg^(-1),变异系数为77.55%,其含量及变异性随土层深度增加而减小。随着复垦年限增加,SOC含量增加,不同复垦方式下SOC含量的分布特征依次为林地(5.31g·kg^(-1))>耕地(2.98g·kg^(-1))>未利用地(2.29g·kg^(-1)),而且林地SOC剖面分布差异最大,耕地SOC含量主要受复垦年限影响。变差分解显示,复垦年限、土层深度和土地利用方式分别可解释SOC含量变化的15.0%、10.3%和2.4%,复垦年限与土地利用方式共同解释11.2%的变化。复垦年限和复垦方式对20cm以下SOC的影响减弱,但复垦年限延长则增强了土层深度和复垦方式对SOC变化的解释度。不同阶段的复垦方式对SOC含量的变化起决定性作用,但复垦过程及工艺的复杂性导致复垦区SOC含量变化仍然存在很大的不确定性。

The soil organic carbon(SOC)is a key indicator for evaluating the change in soil quality.It is of great significance to analyze the evolution process,influencing factors and driving mechanism of how SOC changes in coal mine reclamation areas,and to guide the development of mining area reclamation.In this study,the flat soil reclaimed in Pingshuo opencast coal mine in Shanxi province,China,was investigated,and the spatial series was used to replace the time series for the data to quantify the response of SOC and profile distributions of the reclaimed soils to the reclamation duration and methods.The results show that the SOC content of the reclaimed flat soil ranges from 0.82 to 16.11g/kg with an average of 3.53g/kg,and the coefficient of variation is 77.55%.The content and variability of SOC decrease with the increase in the soil depth.A longer reclamation duration promotes an increase in the SOC content.Under different reclamation methods on different soils,the changes in the SOC contents have the following order:forest land(5.31g/kg)>cultivated land(2.98g/kg)>unused land(2.29g/kg).The profile distribution of SOC content on the forest land is the largest,and the SOC content on the cultivated land is mainly affected by the years of reclamation.The result of variance decomposition shows that the reclamation duration,soil depth and land use types account for 15.0%,10.3%and 2.4%of the change in the SOC content,respectively,while the reclamation duration and land use types jointly account for 11.2%of the change.The influence of reclamation duration and methods on SOC 20cm below the surface is weakened,while a prolonged reclamation duration enhances the interpretation of the soil depth and reclamation methods on the change of SOC content.The reclamation methods at different stages play a decisive role in the change of SOC content,but the complexity of the reclamation process and technology leads to great uncertainty in the change of SOC content in the reclamation areas.