The Role of Plant Diversity in Promoting Recovery of Soil Microbial Communities During Ecosystem Restoration on Reclaimed Mine Lands

Plant establishment is a key component of land reclamation and restoration, but ultimately full recovery of other beneficial ecosystem services that were provided prior to disturbance is desired for successful restoration. Many of these ecosystem services, primarily related to nutrient cycling and other biogeochemical processes, are regulated by microorganisms. However, the factors that promote the return of beneficial soil microorganisms – and the ecological functions they perform – to restored ecosystems are not well understood. Our previous work in the Powell River Project has discovered that the type of vegetation used to reforest reclaimed mine soils may not only control the resulting plant community, but also the trajectory of the soil microbial community and the processes they mediate related to important ecosystem services. In this work, we experimentally tested the hypothesis that carbon substrate diversity, provided by plant root exudates, is an important mechanism in shaping soil microbial communities as ecosystems recover. In a controlled greenhouse experiment, we analyzed microbial community structure and diversity of dissolved organic carbon substrates in experimental PRP soil mesocosms planted with one of five plant diversity treatments: chicory, clover, foxtail, rye, or an even mix of all four. Results indicate that plant species has significant effects on soil dissolved organic carbon substrate quantity and quality, as well as soil microbial community structure, with clover and chicory resulting in the most distinct changes. In addition, among the non-leguminous plant species, patterns of carbon substrate and microbial diversity tracked each other, suggesting an important interaction between the two.