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Carbon cycling in thawing permafrost ecosystems
Permafrost stores ~a third of the world’s soil organic carbon, in a relatively inaccessible frozen form. Under continued climate warming, permafrost is projected to decrease 50% by 2050 and be virtually eliminated by century’s end. Thawed permafrost frequently becomes wetland, which is a major source of the potent greenhouse gas methane, thereby raising the potential for dramatic positive feedbacks to warming. Our interdisciplinary DOE-funded project examines the effects of natural in situ permafrost thaw on carbon cycling, by examining an existing permafrost thaw gradient in subarctic Sweden. We are focusing high-resolution, cutting-edge microbial and biogeochemical investigations across the three habitats defining this gradient: intact permafrost, intermediate-thaw peat bog, and fully-thawed fen wetland. Our results are being integrated into a wetland ecosystem process model that predicts greenhouse gas emissions. SWES-MEL co-leads this work and is one of two microbial ecology labs on the project, and our focus is on molecular analyses of microbial community composition and activity (16S rRNA gene surveys, metagenomics, and metaproteomics). Through this work, we hope to address how permafrost thaw effects carbon cycling, predict the likelihood and magnitude of global warming feedbacks, and add a mechanistic framework for scaling from “genes to ecosystems” in this biome.
- SWES-MEL scientists involved: Eun-Hae Kim, Robert Jones, Gary Trubl, Darya Anderson, Akos Owusu-Dommey, Morgan Binder, Maya Sederholm
- Collaborating Labs: Tyson (Australian Center for Ecogenomics), Saleska (UA), Crill (Stockholm U, Sweden), Chanton (Florida State U), Changsheng Li and Steve Frolking (U New Hampshire).
The Great Barrier Reef "Microbial Buffering" Project”
One of the threats to global reef systems in general, including the Great Barrier Reef, is coastal pollution. In northeastern Australia extensive land-use change over the last century has brought significant agricultural development, which now causes coastal pollution from herbicides, pesticides, nutrients, and organic matter. Our collaborator Gene Tyson put forth the hypothesis that coastal microbial and viral communities may "buffer" reefs from the full impacts of pollution by taking up and/or transforming contaminants, and he, Matt Sullivan and myself (lab lead V. Rich) developed a project to test this hypothesis. We partnered with David Bourne and Britta Schaffelke of the Australian Institute of Marine Science, who run extensive existing monitoring programs of coastal water quality and reef health, so that we could layer microbial and viral investigations on top of this rich and highly relevant metadata.
- SWES-MEL scientist involved: Lynn Massey
- Collaborating Labs: Tyson (Australian Center for Ecogenomics), Sullivan (UA), Bourne & Schaffelke (Australian Institute of Marine Science)
The “Central Dogma” Project, aka Deconstructing scaling ’from genes to ecosystems’: quantifying the relationship of molecular indices andcarbon fluxes in isolates and thawing permafrost
To predict ecosystem and planetary response to a changing climate, scaling from microorganisms to ecosystem processes is required. We propose to meet this challenge of scaling from the genomic diversity of communities to ecosystem-scale processes, i.e. “from genes to ecosystems,” by deconstructing and quantifying the stepwise linkages involved. Specifically, we will move beyond metabolic potential (genomes and metagenomes) to measuring expressed metabolism (meta- transcriptomes and -proteomes) and quantitatively relating it to biogeochemical fluxes. We will do so for the greenhouse gas methane, in controlled laboratory incubations of methane-cycling cultivars and natural communities (specifically, those of the thawing permafrost at our field site).
- SWES-MEL scientists involved: Eun-Hae Kim, Robert Jones
- Collaborating Labs: Saleska (UA), Crill (Stockholm U, Sweden), Chanton (Florida State U), Cadillo-Quiroz (Arizona State University).
Understanding the system response of soil to compost additions, in partnership with the UA Land Stewardship Program
The UA Land Stewardship Program is converting the management of the UA Mall’s turf grass from conventional to organic practices. Turf grass covers more land area in the US than any agricultural crop, and has a higher chemical input than any agricultural crop. Managing it sustainably is key to minimizing its long-term impacts on water supply and watershed and atmosphere quality. Treating turfgrass with compost tea in UA trials resulted in a range of system improvements, including decreased water use, increased C sequestration, deeper root depth, and the almost complete replacement of root-feeding nematodes by beneficial species (Pew and Hollar, 2011). Remarkably, compost tea application has also been shown to directly stimulate some plant “immune system” response, with increased protection from soil microbial and fungal pathogens; this response may be due to the direct physical interaction of compost-delivered microbes and plant root border cells (Curlango-Rivera, submitted). Reduction in fertilization should also reduce turf grass emissions of the greenhouse gas N2O, since its fluxes are strongly coupled to excess nitrogen related to fertilizer additions (Townsend-Small and Czimczik, 2010), however the full picture of compost effects on greenhouse gas emissions has not been performed. Now that all UA turfgrass is being transferred to organic management, SWES-MEL is co-leading a team of UA researchers in a wholistic assessment of how compost treatments impact the soil community ecosystem and in turn influence greenhouse gas balance. Soil microorganisms are responsible for most below-ground carbon and nitrogen cycling, and therefore greenhouse has cycling, and so our lab’s research on the microbial communities is central to understanding ecosystem response. This research will allow turfgrass managers to make more informed decisions about their management practices, and will also be relevant to sustainable management decisions using compost treatments on diverse agricultural crops.
- SWES-MEL scientists involved: Vytas Pabedinskas, Bree Gomez
- Collaborators: van Haren Lab (Biosphere 2, UA), Chester Phillips (Compost Cats, UA), Troy Hollar (Merlin Organics), Gallery Lab (SNRE, UA), Hawes Lab (SWES, UA), Pavao-Zuckerman Lab (Biosphere 2, UA), Dontsova Lab (Biosphere 2, UA).