Mining subsidence area reconstruction with N2-fixing plants promotes arbuscular mycorrhizal fungal biodiversity and microbial biomass C:N:P stoichiometry of cyanobacterial biocrusts

Vegetation restoration may promote the development of biological soil crusts (biocrusts) that are colonized by arbuscular mycorrhizal fungi (AMF) and play an important role in microbially-mediated mineral nutrient cycling. However, little is known about biocrust AMF communities or microbial biomass carbon (C), nitrogen (N) and phosphorus (P) cycling during vegetation restoration in coal mining subsidence areas. Here, we examine cyanobacterial biocrust microbial biomass C:N:P stoichiometry and AMF communities under five revegetation types, i.e., field plots planted with Hippophae rhamnoides, Xanthoceras sorbifolium, Cerasus humilis, Cerasus szechuanica, or Amorpha fruticosa. Cyanobacterial biocrusts under H. rhamnoides and A. futicosa had the highest estimated microbial biomass C:N:P and AMF alpha-diversity values but the lowest pH and electrical conductivity. Moreover, four AMF genera (Ambispora, Glomus, Diversispora, and Paraglomus), one order (Glomerales) and one class (Glomeromycetes) were the most abundant AMF in cyanobacterial biocrusts under the five revegetation types. Vegetation cover induced by revegetation type had direct positive effects on biocrust biomass and was the strongest driver of AMF diversity and microbial biomass C:P ratio. The N-2-fixing plant species (A. fruticosa and H. rhamnoides) are preferable in restoration strategies in enhancing the development of cyanobacterial biocrusts and thus promoting the soil AMF community and microbial mineral nutrient cycling during vegetation reconstruction. The results provide a clearer understanding of the ecological functions of cyanobacterial biocrusts and further facilitate the assessment of ecosystem services and sustainable development in vegetation reconstruction in coal mining subsidence areas.

Automated summary

Vegetation restoration can enhance the development of cyanobacterial biocrusts and the diversity of AMF communities, with N2-fixing plant species playing a key role in this process. Vegetation cover is a major determinant of biocrust biomass and influences AMF diversity and microbial biomass C:P ratio.