Characterizing Microbial Community Development in Reclaimed Mine Soils

A significant amount of the research to date at the Powell River Project (PRP) has been focused on reforestation, with the assumption that tree growth will ultimately lead to the re-establishment of a fully functioning forest ecosystem. Soil microorganisms are a critical component of this system because they mediate many of the ecosystem services for which forests are valued including carbon sequestration, soil formation, nutrient retention, watershed protection, and groundwater purification. We are characterizing the response of soil microbial communities to land reclamation approaches in the PRP to provide critical information about the restoration of the microbial component of the forest ecosystem. The objectives of this project are threefold: 1) characterize the recovery of soil microorganisms over time; 2) determine if alternate reclamation practices affect microbial diversity and community structure; and 3) compare restored microbial communities to un-mined forest soils to identify potential indicators that ‘healthy’ microbial communities are returning to reclaimed soils. We have identified a variety of reclamation plots within the PRP that represent a range of ages between 5 and 30 years to look at the effects of time. We have also sampled two other sets of to determine effects of reclamation practices: one where soils were amended with biosolids and another that was planted with pines as opposed to the standard hardwood mix. We are using genomic sequencing to fully characterize bacterial and fungal organisms present in soil samples from each plot to determine microbial diversity and community structure. Preliminary results suggest that bacterial communities recover quickly, becoming indistinguishable from communities in undisturbed soils within 10 to 30 years. In addition, certain taxa such as Bacteroidetes, Verrucomicrobia, and Gemmatimonadetes appear to respond to age since reforestation and may contain taxa that can be used to gauge restoration progress.