露天煤矿复垦土壤活性有机碳影响因素及管控策略

The influencing factors and control strategies of soil labile organic carbon in opencast coal mine reclamation

为揭示露天矿区土壤活性有机碳(LOC)时空分布规律及影响机制,以平朔露天煤矿9种复垦模式和4个复垦年限为研究对象,采用单因素方差分析研究了LOC时空分布规律;基于结构方程模型和冗余分析探讨了LOC影响因素。结果发现:(1)LOC有明显表聚特征;(2)土地复垦能显著增加LOC含量,不同复垦模式LOC含量差异显著,呈现混交林>原地貌>纯林的现象,油松×刺槐×榆树恢复效果最佳;(3)LOC含量随复垦时间延长而显著增加,但复垦26年后LOC/SOC未达到原地貌水平;(4)直接影响LOC的因素依次为土壤理化性质>土层深度>复垦时间>复垦模式;(5)土壤环境因子对LOC的总解释度为68.52%,其中黏粒、AK及SW对LOC的解释度高于其他因子。结果表明:植被重建时应采取多层次、多样化的植被种植策略,适当增加本地优势植被比例,并注重保护原有微生物群落;改善土壤质地、加强水肥管理是促进矿区生态恢复的关键。本文可为露天矿区复垦提供固碳增汇策略和相应理论支持。

In order to reveal the spatiotemporal distribution patterns and influencing mechanisms of soil labile organic carbon(LOC)in the reclamation area of opencast coal mines,we selected nine different vegetation combinations and sample plots spanning four reclamation years from the soil dumping grounds in the Pingshuo opencast mining area,using an undisturbed elm forest as a control area.We employed one-way ANOVA to investigate the distribution patterns of soil LOC within the sample plots.Furthermore,we explored the influencing factors of soil LOC using Structural Equation Modeling and Redundancy analysis methods.and further examined the functional relationship between soil physicochemical properties and soil LOC through regression analysis.The results indicate that:(1)Soil LOC in various areas has obvious surface aggregation characteristics and the trend decreases with the increase of soil depth.(2)Land reclamation can significantly increase soil LOC content,but significant differences in soil LOC exist under various reclamation modes,with mixed forests>original landforms>pure forests,and the Pinus tabulaeformis×Robinia pseudoacacia×Elm tree combination demonstrating the most effective restoration compared to other soil LOC.(3)Soil LOC significantly increases with reclamation time,and the recovery rate of soil LOC is higher than that of soil organic carbon,but even after 26 years,LOC/SOC levels do not reach those of the original landform.(4)Direct factors affecting soil LOC are soil physicochemical properties>soil depth>reclamation time>reclamation mode.(5)The overall explanatory power of soil environmental factors for soil LOC is 68.52%.The order of explanatory power is clay>available potassium>soil moisture content>sand>pH>powder>alkaline nitrogen>bulk density>available phosphorus.The explanatory power of clay particles,available potassium,and water content for LOC is higher than other factors.The above results indicate that multilevel and diversified vegetation planting strategies should be adopted during vegetation reconstruction,with an appropriate increase in the proportion of local advantageous vegetation and attention paid to protecting the original microbial community of the reclaimed land.At the same time,improving soil texture and strengthening water and fertilizer management are key to promoting ecological restoration in mining areas.The above research can provide carbon sequestration and sink enhancement proposals and corresponding theoretical support for the reclamation of opencast mining areas.