Effects of re-vegetation type and arbuscular mycorrhizal fungal inoculation on soil enzyme activities and microbial biomass in coal mining subsidence areas of Northern China

Coal mining subsidence leads to the degradation of vegetation cover and reduces soil quality. Soil microbes play a critical role in the recycling of soil nutrients and soil fertility. Both arbuscular mycorrhizal fungi (AMF) and artificial re-vegetation play key roles in regulating biogeochemical systems. Here, we investigated the effects of AMF inoculation and artificial re-vegetation type on soil invertase, urease and alkaline phosphatase activities, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and their correlations with soil physicochemical properties using redundancy analysis and partial redundancy analysis in order to enhance and reclaim soil quality and the ecological efficiency of coal mining subsidence areas. The results show that soil nutrients and soil enzyme activities in FM (inoculated with Funneliformis mosseae) soils were significantly higher than in control (uninoculated) soils under all re-vegetation types, and soil organic carbon content (SOC) was highest in Hippophae rhamnoides (HR) soils. Soil MBC followed the order HR > Amorpha fruticosa (AF) > Xanthoceras sorbifolium (XS) > Cerasus humilis (CH). Soil total nitrogen (TN), dissolved organic nitrogen (DON) and nitrate nitrogen (NO3—N) were key factors affecting soil microbial activity in the FM soils, whereas SOC, DON, and soil C/N ratio were the important factors in control soils. Soil microbial activity was affected by soil factors to different degrees. AMF are essential for plant acquisition of soil resources, especially soil nitrogen. AMF were correlated with the potential activities of N acquisition enzymes in soil and affected N cycling in the coal mining subsidence soils.