The Science

A detailed biogeochemical and microbial study of three moss-dominated, low-pH peatlands in northern Minnesota, as well as a survey of methane production potentials in 19 peatlands in the Upper Peninsula of Michigan, showed a large difference in methane production and emissions in bog-like peatlands despite initial similarities. These experiments demonstrate that it is common to have high variation in methane cycling in seemingly similar peatlands within a single geographical region.

The Impact

Caution is urged in extrapolating results from a small number of bog and peatland sites to regional responses in methane dynamics in peatlands due to considerable variability in methane cycling.

Summary

There is limited understanding of the variability associated with methane (CH₄) cycling among low-pH, Sphagnum moss–dominated peatlands within a geographical region. Here, a team of researchers from the University of Oregon and Chapman University report the results from two studies exploring the controls of CH₄ cycling in peatlands from the Upper Midwest (USA). Potential CH₄ production and resultant carbon dioxide (CO₂):CH₄ ratios varied by several orders of magnitude among 19 peatlands in the Upper Peninsula of Michigan. They also more intensively examined CH₄ dynamics in three bog-like, acidic, Sphagnum-dominated peatlands in northern Minnesota. Net CH₄ flux was lowest in the peatland with well-developed hummocks, and the isotopic composition of the :CH₄ along with methanotroph gene expression indicated a strong role for CH₄ oxidation in controlling net CH₄ flux. These experiments demonstrate that it is common to have high variation in CH₄ cycling in seemingly similar peatlands within a single geographical region. Caution should be used when extrapolating data from a single site to the landscape scale, even for outwardly very similar peatlands, and it is best to place manipulative experiments in multiple peatlands to encompass this variability. The macroscale development of peatlands, and concomitantly their microtopography as expressed in the proportion of hummocks, hollows, lawns, and pools, needs to be considered as central controls over CH₄ emissions in methane modeling.

Principal Investigator

Scott Bridgham
Institute of Ecology and Evolution, University of Oregon
bridgham@uoregon.edu

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

This material is based on work supported by the Office of Biological and Environmental Research, within the U.S. Department of Energy (DOE) Office of Science, under award numbers DE-SC0008092, DE-SC0014416, DE-SC0007144, DESC0012288, and DE-SC0012088; the DOE Office of Science Graduate Fellowship Program (DE-AC05- 06OR23100); and the National Science Foundation under award number DEB-0816575.

Related Links

• Supporting Data

References