Peatlands and Climate Change
Microbes, Plants, and Carbon Storage in Northern Peatlands
Global Climate Chance
Peatlands are wetlands that store one-third of all soil carbon on Earth and currently act as a major source of the greenhouse gas, methane, to the atmosphere. Peatland soils can be considered as a “carbon bank”, and there is concern that this carbon could be withdrawn or released via microbial processes to the atmosphere in response to climate change. Two major questions being addressed in peatlands by the Kostka Lab are: 1) Why do boreal peatlands store so much carbon?, and 2) Will some or all of this stored carbon be released to the atmosphere in response to climate change? The assumption is that more carbon enters these ecosystems as photosynthetic production then leaves as respiration. But why is it that respiration does not keep up with photosynthesis? Is it because these ecosystems are generally cold, acidic, anaerobic, or contain plant exudates poison microbial metabolism?
Given their global extent and uncertain fate with climatic change, boreal forests are considered a high priority for climate change research. Peatlands research in the Kostka lab is being conducted at the Marcell Experimental Forest (MEF) in northern Minnesota where Oak Ridge National Laboratory (ORNL) and the USDA Forest Service have developed a climate manipulation field site known as Spruce and Peatland Response Under Climatic and Environmental Change (SPRUCE). At MEF, work is focused on a type of peatland called a “bog”. Bogs are nutrient-poor ecosystems that receive most of their nutrients from precipitation as rain or snow. We work closely with geochemists and analytical chemists to understand the controls of the microbially-mediated carbon cycle and the potential response of the carbon cycle to climate change in bogs. We have used next generation gene sequencing approaches to describe the microbial groups present in bog soils at unprecedented detail. We generated the first metagenomes from bog soils, which tells us about potential metabolic pathways that microbes use to cycle carbon and nutrients in the bog. A metagenomic approach was also used to interrogate the potential metabolism of archaea that are very abundant in deep peat soils. These same groups of archaea are abundant in soils on a global scale. These abundant archaea are not methanogens and they have not yet been grown in culture. Thus, we have provided the first glimpse of their potential metabolism to guide future cultivation efforts.
At the bog in Minnesota, the SPRUCE project has been constructing giant, 12 x 8 m enclosures, to simulate climate change. Inside the chambers, the bog is heated to between 0 to +9 oC above ambient temperature, and carbon dioxide levels will be elevated in half of the chambers to twice current atmospheric levels. From June 2014 to June 2015, the Kostka lab worked with collaborators across the U.S. to perform what was called the Deep Peat Heat experiment led by ORNL. Soil heating was initiated in the climate enclosures and soil cores were sampled to determine the effects of soil temperature on microbial communities and processes. Currently, we are using omics- based methods to examine shifts in the structure and function of soil microbial communities due to temperature changes.
More information on the SPRUCE project can be found at the SPRUCE homepage
From the Kostka Lab:
From the Glass Lab:
- Melissa Warren
- Jeff Chanton and William Cooper, Florida State University in Tallahassee, Florida
- Chris Schadt, David Weston, Paul Hanson, Oak Ridge National Laboratory in Oak Ridge, Tennessee
- Jennifer Glass, Georiga Institute of Technology in Atlanta, Georgia
- Scott Bridgham, University of Oregon in Eugene Oregon
- Jason Keller, Chapman University in Orange, California
- Kirsten Kusel, Friedrich Schiller University, Jena, Germany
Recent Publications:Lin, X., K. M. Handley, J. A. Gilbert, J. E. Kostka. 2015. Metabolic potential of fatty acid oxidation and anaerobic respiration by abundant members of Thaumarchaeota and Thermoplasmata in deep anoxic peat. ISME Journal (in press)
Lin, X., M. M. Tfaily, J. M. Steinweg, P. Chanton, K. Esson, Z. K. Yang, J. P. Chanton, W. Cooper, C. W. Schadt, J. E. Kostka. 2014a. Microbial community stratification linked to utilization of carbohydrates and phosphorus limitation in a boreal peatland at Marcell Experimental Forest, Minnesota, USA. Applied and Environmental Microbiology 80: 3518-3530
Lin, X., M. M. Tfaily, S. Green, J. M. Steinweg, P. Chanton, A. Imvittaya, J. P. Chanton, W. Cooper, C. Schadt, J. E. Kostka. 2014b. Microbial metabolic potential for carbon degradation and nutrient (nitrogen and phosphorus) acquisition in an ombrotrophic peatland. Applied and Environmental Microbiology 80: 3531-3540
Tfaily, M.M., W. T. Cooper, J. Kostka, P. R. Chanton, C. W. Schadt, P. J. Hanson, C. M. Iversen, and J. P. Chanton. 2014. Organic Matter Transformation in the Peat Column at Marcell Experimental Forest: Humification and Vertical Stratification. Journal of Geophysical Research: Biogeosciences 119: 661-675
Lin, X., S. Green, M. M. Tfaily, O. Prakash, K. T. Konstantinidis, J. E. Corbett, J. P. Chanton, W. T. Cooper, and J. E. Kostka. 2012. Microbial community structure and activity linked to contrasting biogeochemical gradients in bog and fen environments of the Glacial Lake Agassiz Peatland. Appl. Environ. Microbiol. 78: 7023-7031