Soil Microbial Communities in Long-Term Soil Storage for Sand Mine Reclamation

The success of ecosystem restoration following mining could be improved through consideration of the soil microbial community, which forms the foundation of ecosystems. Through sequencing we can assess the response of the microbial community to stresses such as stockpiling, and measure community recovery. We sequenced fungal and bacterial communities associated with intact Banksia woodland reference soils and stockpiled topsoil stored for one to ten years following sand mining in Western Australia. We found that both bacterial and fungal richness declined, but that the fungal community returned to a state similar to reference soils, whereas the bacterial community did not. Notably, Bradyrhizobium was absent from 10-year soils, indicating a possible lack of inoculum available to colonize legumes that are often used for revegetation. Soil fungi and bacteria respond differently to stockpiling and key taxa such as Bradyrhizobium could be lost. In addition, changes in the bacterial community may signal a reduction in plant-available nitrogen and a shift towards more anaerobic conditions consistent with previous studies. These changes in microbial communities support previous findings of reduced plant performance on 10-year stockpiled soils and emphasize the importance of considering soil age during restoration.