Study On The Influencing Factors Of Organic Carbon Accumulation In Reclaimed Soil In Open Pit Mine Based On Complex Network

Numerous factors and complex process affect soil organic carbon accumulation.Determining the influencing factors of soil organic carbon scientifically can not only improve soil physical and chemical properties,but also better restore the ecological environment of mining area.The data of the soil,topography and vegetation from a total of 50 sampling sites located in the West,South and Inner dumps in the Antaibao coal mine area were collected and determined.SPSS software was used to conduct correlation analysis,and Gephi was used to calculate complex index.The main factors affecting soil organic carbon accumulation and the affecting path were analyzed using following,including degree,closeness central degree and robustness.The influence mechanism of soil organic carbon accumulation resulted from soil,topography and vegetation factors were explored.The main conclusions of the study are as following:(1)Total nitrogen and sand content were the main soil factors affecting soil organic carbon accumulation,and canopy density and vegetation coverage were main vegetation factors.Correlation between topography factors and soil organic carbon accumulation was not significant.(2)The degree,closeness centrality,betweeness centrality,average path length and average clustering coefficient could reflect the roles of different factorson soil organic carbon accumulation from different aspects.Based the descriptive statistical analysis on the network index,the average length path was 1.824 and the average clustering coefficient was 0.588.Therefore,this network possessed the characteristics of randomness and locality,and it has the clear community structure;namely the relationships among the soil physical properties were close,and the relationships between soil chemical properties and vegetation were close.The degrees of total nitrogen,clay content,silt content,sand content,tree volume,canopy density were relatively high,and their roles in the accumulation of soil organic carbon were relatively high.(3)Total nitrogen had the highest betweenness centrality,and it played the main connective function in the network and could also change the process that other factors affected soil organic carbon accumulation.Silt content and clay content also has a relatively high betweenness centrality,and they played the roles connecting soil properties and topographic index.The effect of topography on soil organic carbon was mainly implemented by clay content and silt content.(4)The smaller average path length and higher clustering coefficient showed that the network structure was cramped and the effect of changing some factors on soil organic carbon accumulation was little.The effects of total nitrogen,vegetation volume and gravel content on the stability of network structure and accumulation of soil organic carbon were the highest.In order to accelerate soil organic carbon accumulation,increasing total nitrogen content and improving soil physical properties were the effective measures.Vegetation volume and canopy density can significantly affect the accumulation of soil organic carbon,so broad-leaved tree species should be selected for vegetation reconstruction;moreover,increasing vegetation coverage can increase the accumulation of soil organic carbon,arbor-shrub-grass reclamation mode should be used.