SPRUCE picture - Version 2

My group studies the response of soil microbial communities to a changing global environment and to other human influences, in a manner that best informs how we may predict or mitigate the effects of these disturbances. We study microbial responses from the perspective of microbial growth, nutrient cycling, and biogeochemistry, with a central focus on the relationship between microbial community scale dynamics and changes in ecosystem scale processes.


Specific topics

Microbial local adaptation and responses to global change

I have a long-term interest in exploring how microbial responses to multiple global changes fluctuate over time, space, and in relation to local adaptation and natural disturbance. One specific project is to better understand the role of microbial communities in ecosystem responses to global change by investigating microbial responses to wildfire disturbance and multiple global changes at the Jasper Ridge Global Change Experiment.

A new project in this theme is the SPRUCE project at the Marcell experimental forest in northern Minnesota, where we have starting working in summer 2014.

Microbial communities, ecosystem function, and forest biodiversity

Tree species diversity and composition influences soil nutrient status in relation to microbial decomposition and carbon cycling, microbial nitrogen cycling, and microbial growth and broad community composition. A focus of this research is on the relationships between plant growth and physiological traits, diversity, soil stabilization, and nutrient cycling by monitoring microbial community structure and functions associated with tree individuals along a diversity gradient from 1 to 24 tree species in subtropical China, as part of the BEF-China project, in close cooperation with the Helmholz-UFZ soil ecology department. In addition to this main work, we have cooperative experiments on microbial decomposition of litter and wood in relation to forest successional stages and biodiversity

I have also done work in temperate systems regarding forest diversity, which will hopefully be published soon.

Microbial adaptation and mediation of soil quality carbon cycling as win-wins for agricultural adaptation and mitigation to climate change.

Microorganisms are strong mediators of carbon cycling and could be at the center of ecosystem feedbacks to climate change by mediating respiratory CO2 loss versus soil C storage. It has also been increasingly established that soil organic carbon (SOC) is highly dynamic and can be transformed or stabilized by diverse processes, both biotic and abiotic, in relation to soil management.

We  have several projects in this area. One is in partnership with the Minnesota NRCS, to test the efficacy of their Soil Health Initiative program. In fall of 2016 we sampled farms with acreage in or not in the program to test the efficacy of using diverse cover crops to build soil quality. Another emphasis of this work is to create fact sheets to translate scientific language in a better way for producers and other end users of our data. For more information on their program, visit the NRCS website. We have already seen many beautiful soils and expect results in early 2017, where we will also test for resilience to large storm events. A second project is to test the soil C storage and C footprint potential, and microbial underpinnings of that potential, on a perennial grain crop being developed at UMN in cooperation with Forever Green. A third project on management and outreach is on high tunnel management and sustainability education, with Dr. Julie Grossman.

My group has also used different microbial biomarkers to determine short-term and long-term microbial contribution to soil C cycling  in relation to long-term agricultural management (see Schmidt et al 2015) based on 100 year old field trials (Helmholz-Centre for Environmental Research, Soil Ecology department).


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