Inland wetlands produce, biogeochemically process and sequester carbon. Wetlands that are hydrologically connected to stream and river networks are commonly considered to be major sources of carbon that may be biologically or photochemically processed in-stream, or exported to coastal regions. However, very little is known about the potential or actual lateral carbon fluxes from different major wetland types, or the downstream fate of that carbon (rapid decomposition vs. sequestration vs. export). Major questions: What is the variability in potential carbon sources (as dissolved organic C, dissolved inorganic C, CO2 and CH4) from major inland wetland types to inland waters? What metrics and/or markers (chemical, biological) are [...]
Summary
Inland wetlands produce, biogeochemically process and sequester carbon. Wetlands that are hydrologically connected to stream and river networks are commonly considered to be major sources of carbon that may be biologically or photochemically processed in-stream, or exported to coastal regions. However, very little is known about the potential or actual lateral carbon fluxes from different major wetland types, or the downstream fate of that carbon (rapid decomposition vs. sequestration vs. export).
Major questions:
What is the variability in potential carbon sources (as dissolved organic C, dissolved inorganic C, CO2 and CH4) from major inland wetland types to inland waters?
What metrics and/or markers (chemical, biological) are useful in determining the presence of wetland-derived carbon in inland waters?
How susceptible is wetland-derived organic carbon to biodegradation vs. sequestration and/or lateral export (within wetlands, and in inland waters)?
Our sampling approach targets wetlands distinguished by vegetation type consistent with national wetland classifications and mapping products. The US Fish & Wildlife Service National Wetlands Inventory (NWI) Classification is based primarily on dominant vegetation (forested, shrub, emergent) and hydrologic regime; the National Land Cover Database (NLCD) also distinguishes wetland type based on vegetation (woody, herbaceous) and hydrologic regime.
Current sampling efforts to characterize wetland carbon chemistry and lateral transfer:
Wetland carbon exports to high-elevation streams, Rocky Mountain National Park (RMNP)
Three high elevation streams that flow through wetland complexes and have minimal human impact were established as study sites as part of the LandCarbon Headwater Streams Project (PI: Dave Clow). The wetland complexes include an emergent/shrub complex, a shrub/forested complex, and a shrub wetland complex (according to NWI). Continuous sensor packages measuring fluorescent dissolved organic matter (FDOM) and dissolved CO2 are installed above and below the wetland complexes, allowing for high frequency measurement of C inputs and exports from the wetlands. To complement these continuous data, regular (weekly to bi-weekly) synoptic sampling of the streams will be conducted during summer and fall for detailed changes in organic carbon concentration and chemical character, dissolved CO2 and CH4, and gas fluxes as the streams flow through the wetland complexes.
2. Wetland carbon chemistry survey in the Upper Mississippi River Basin (UMRB)
The UMRB is a wetland-rich area. Recently completed LandCarbon studies of streams and rivers in this region (Inland Waters Project, PI: Rob Striegl) demonstrate that DOC yields are greater from watersheds having high wetland density. We will conduct a survey of wetland carbon chemistry in the Chippewa River basin, targeting tributary basins sampled for stream chemistry that have high wetland density and high DOC yields. These watersheds are dominated by forested wetlands, with lower coverages of shrub and emergent wetlands. We will sample surface and pore waters from these distinct wetland types to characterize carbon chemistry and utilize analytical techniques to determine source-water biomarkers from different wetland types.