Moisture, redox dynamics, and soil biogeochemical resilience
Climate change is altering soil moisture regimes through more intense flooding, changing tidal inundation, and shifting drainage following permafrost thaw. When soils become saturated, declining oxygen availability alters microbial activity and the chemical reactions that regulate carbon and nutrient cycling. We examine how intermittent flooding, soil saturation, and associated redox transitions affect microbial communities and soil organic matter. A particular focus is on whether and how microbial functions recover and if organic matter is retained, transformed, mobilized, or lost following moisture disturbance events. We study these processes across managed and natural ecosystems, including agricultural soils, wetlands and tidal environments, and landscapes undergoing permafrost thaw.
Photo: M. Burnett
Soil organic matter molecular composition and persistence
Soil organic matter (SOM) is chemically and functionally complex, providing the energy and nutrients needed for an active, diverse soil food web and supporting plant productivity. How SOM accumulates and is transformed depends on its chemical composition, biological origins, and interactions with the soil environment. By linking molecular composition, using pyrolysis–gas chromatography/mass spectrometry, isotopes, and soil fractionation, with microbial processes, we aim to identify the factors that promote SOM retention and determine when different pools of SOM are vulnerable to mobilization or loss under environmental and land-use change.
Photo: D. Olefeldt
Plant diversity and belowground communities
Plants influence carbon storage through the quantity and chemistry of their inputs, their interactions with microbial and mycorrhizal fungal communities, and their effects on the soil environment. We investigate how crop and tree species and functional diversity structure belowground communities and influence carbon and nitrogen cycling. We ask if and how changes in belowground communities mediate the effects of plant diversity on soil organic matter formation, nutrient retention, and resilience to environmental change and land use disturbances.