Insights into peatland carbon cycling derived from integration of Omics with biogeochemical profiling
EMSL Project ID
48292
Abstract
Peatlands are one of the most important ecosystems providing feedbacks to the climate system because they store a large component (>30%) of the world's soil C stocks. Peatlands also are found predominantly at northern high latitudes, which are expected to experience warming at twice the global rate. Peat accumulation generally depends on flooded conditions that impede rates of decomposition. Thus, the formation and maintenance of boreal peatlands are influenced by relatively low rates of evaporation and a relatively high water table position. The strong controls of climate and hydrology on peat formation make peatlands particularly sensitive to climatic conditions. However, there is much uncertainty concerning how global change will affect peatland C balance because most studies cannot account for vegetation successional dynamics that will occur with changes in temperature or water table. To disentangle interactive effects of vegetation and hydroclimate we established a full factorial peatland ecosystem manipulation experiment (PEATcosm) wherein we experimentally alter water table and plant functional groups (Ericaceae, sedges) to characterize their effects on microbial communities and trace gas production. Complementary manipulation experiments are planned within a forested peatland (SPRUCE experiment). Overall, we expect that the composition of humic substances of tissue, litter, and rhizosphere exudates vary among plant functional types, particularly sedges and ericaceous shrubs that are both important components of vegetation biomass in peatlands, and also the Sphagnum species that are responding strongly to treatments. We predict strong interactive effects of hydroclimate and plant functional traits (for example, aerenchyma cells) in regenerating the pool of election acceptors associated with humic substances. These factors, in turn, likely exert strong control over microbial community composition and terminal metabolism in peatlands. Findings to date show that treatment conditions which favored peat oxidation (lowered water table and preponderance of sedges) resulted in porewater with higher aromaticity, lower organic acid concentrations, and higher oxidation reduction potentials. While these activities will provide important insights into the genetic potential and activity of microbial regulators of peatland C cycling in relation to changes in environment and vegetation community, our insights into the consequences of changes in these complex microbial communities will be limited unless we can establish a direct linkage to altered biogeochemistry. We propose to complement existing activities with metaproteomics, meta-metabolomics, and detailed characterization of the solid and dissolved phase chemistry of the peat, leveraging existing resources while taking full advantage of the advanced analytical capacity of EMSL in addressing our hypotheses.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Kane E., T.J. Veverica, M. Tfaily, E.A. Lilleskov, K.M. Meingast, R. Kolka, and A.L. Daniels, et al. 2019. "Reduction-Oxidation Potential and Dissolved Organic Matter Composition in Northern Peat Soil: Interactive Controls of Water Table Position and Plant Functional Groups." Journal of Geophysical Research. Biogeosciences. PNNL-SA-150365. doi:10.1029/2019JG005339