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EEB Thursday Seminar: Fens, bogs, and polygons (oh my!): Effects of ecosystem succession and permafrost on wetland carbon dynamics

Claire Treat, Max Planck Institute for Meteorology, Hamburg, DE
Thursday, October 20, 2016
4:00-5:00 PM
1210 Chemistry Dow Lab Map
Wetlands are an important component of the hydrological cycle, a globally important carbon stock, and the largest natural source of atmospheric methane, a potent greenhouse gas. However, not all wetlands function in the same way due to the combined effects of hydrology, nutrient status, and vegetation composition. Wetland ecosystem function, such as apparent carbon accumulation rates and methane emissions, differ significantly among wetland types and thus necessitate a distinction among wetland environmental classifications when considering wetlands in the global carbon cycle. Finally, permafrost is common in high-latitude wetlands and effects of permafrost thaw dramatically alter the ecosystem carbon balance. Understanding the permafrost history and effects on peatlands is key to understanding the future response of soil carbon stocks in high latitude wetlands to climate change.

Here, I discuss the effects of permafrost aggradation and thaw on high-latitude wetland ecosystem succession, soil properties, carbon accumulation rates, and methane emissions using data synthesis of peatland plant macrofossil records of 1060 peat cores from more than 500 sites from across the northern hemisphere. The wetland environmental type (fen, bog, tundra and boreal permafrost, including polygons, and thawed permafrost) was classified using the composition of plant macrofossils within the peat core records. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, N content, and carbon accumulation rates. In the conceptual model of wetland ecosystem succession, fens transition to bogs as organic matter accumulates and then to permafrost peatlands in high latitudes. However, the data showed that ecosystem succession was more complex, including numerous transitions from bogs to fens, permafrost aggradation within fens, and permafrost thaw and re-aggradation. Finally, I use the records of the wetland environmental type from the data synthesis to reconstruct methane emissions from northern high-latitude wetlands in the present day and in the past.
Building: Chemistry Dow Lab
Event Type: Lecture / Discussion
Tags: Biology, Ecology, Environment, Lecture, Science
Source: Happening @ Michigan from Ecology and Evolutionary Biology, Program in Biology, EEB Thursday Seminars