Analysis of damage process and mechanism for plant community and soil properties at northern Shenmu subsidence mining area

The quality of soil and plant community structure were analyzed using factor analysis based on the investigation of plant community characteristics and the examination of soil properties in different years of coal mining subsidence (1, 2, 5, 10 a, and un-subsidence area) at northern Shenmu mining area. Meanwhile, redundancy analysis and cluster analysis were used to study the relationship and succession process between plants and soil. The vegetation-soil coupling model was used to determine the coordination of soil properties and plant community in five periods of coal mining subsidence. The results show that: (1) Disturbance of the subsidence was an important reason for the degradation of the soil quality and the vegetation structure in the subsided area. There was a natural restoration trend of plant-soil ecosystem with the passage of subsidence time. Unfortunately, the plant community structure and soil properties could hardly be restored to the pre-collapse level after even 10 years of natural succession. (2) Soil organic matter, water, and microbes were the core of soil nutrient cycling process and the key factors to determine plant community characteristics. And soil hardness, available nutrients and enzymes were the major influence factors of plant community productivity and diversity. However, the total nutrient was proved to be not so important factors for plant community. (3) Plant communities and soil properties at subsidence area under natural restoration could be divided into three stages, namely the degradation, improvement, and initial recovery stage. (4) There was a trend of recovery for the coordination of vegetation and soil after two years of subsidence. However, it could hardly be well-coordinated ecotype in even 10 years of coal mining subsidence. The results indicated that coal mining had continuity damage to the ecological environment, and the self-healing of ecosystem was weak at northern Shenmu mining area. Therefore reducing the mining damage and achieving the combination of natural and artificial restoration should be the guiding principle of the ecological environment protection in this area.