Marshes typically absorb more carbon dioxide (CO2) from the atmosphere than they release, making them net sinks for carbon dioxide. Our studies of carbon dynamics that included extended dry periods indicated an increase in carbon losses and alterations in greenhouse carbon balance (amount of CO2 sequestered/CH4released). Anticipated increases in dry season duration driven by reduced water availability can switch the marsh from a carbon sink to a source, increasing contributions to atmospheric greenhouse gases.
- Key Findings
Our researchers have been using multiple approaches to measure the exchange of carbon among the atmosphere, water and plants. Long-term measurements include biosphere-atmosphere exchange of carbon dioxide and methane (two major greenhouse gases), plant evapotranspiration and production rates, transport of carbon in water, and soil carbon accumulation and loss. These long-term measurements capture the variability in water availability and its influence on carbon allocation among ecosystem compartments, and show that variability in water level is an important driver of atmospheric-biospheric change.
This data formed an empirical basis for simulations that show that prolonged droughts, anticipated with climate change and reduced water availability, will decrease the capacity of wetlands to fix and store carbon.
Eddy covariance and meteorological tower in a long-hydroperiod Everglades marsh during the height of the wet season, 2008 (at SRS2). Photographer: Dr. Jessica Schedlbauer
Changes in the average gross ecosystem exchange (GEE, uptake of carbon from the atmosphere by plants), ecosystem respiration (Reco, loss of carbon from biosphere to atmosphere), and net ecosystem exchange (NEE, balance of carbon between the atmosphere and biosphere) over the study period in response to changes in water level for all drought scenarios. NEE and GEE were lowest (greater carbon uptake) during periods of inundation and highest (greater carbon release to the atmosphere) during drought simulations. Reco increased during drought simulation up until water began limiting respiration rates (Malone et al 2013).
- Related Publications
Jimenez, K.L., G. Starr, C. Staudhammer, J. Schedlbauer, H. Loescher, S.L. Malone, S. Oberbauer. 2012. Carbon dioxide exchange rates from short- and long-hydroperiod Everglades freshwater marsh. Journal of Geophysical Research 117: G04009. DOI: 10.1029/2012JG002117
Malone, S.L., C. Staudhammer, H. Loescher, P.C. Olivas, S. Oberbauer, M.G. Ryan, J. Schedlbauer, G. Starr. 2014. Seasonal patterns in energy partitioning of two freshwater marsh ecosystems in the Florida Everglades. Journal of Geophysical Research: Biogeosciences 119(8): 1487-1505. DOI: 10.1002/2014JG002700
Malone, S.L., G. Starr, C. Staudhammer, M.G. Ryan. 2013. Effects of simulated drought on the carbon balance of Everglades short-hydroperiod marsh. Global Change Biology 19: 2511-2523. DOI: 10.1111/gcb.12211
Schedlbauer, J., J. Munyon, S. Oberbauer, E.E. Gaiser, G. Starr. 2012. Controls on ecosystem carbon dioxide exchange in short- and long-hydroperiod Florida Everglades freshwater marshes. Wetlands 32: 801-812. DOI: 10.1007/s13157-012-0311-y
Schedlbauer, J., S. Oberbauer, G. Starr, K.L. Jimenez. 2010. Seasonal differences in the CO2 exchange of a short-hydroperiod Florida Everglades marsh. Agricultural and Forest Meteorology 150(7-8): 994-1006. DOI: 10.1016/j.agrformet.2010.03.005
Schedlbauer, J., S. Oberbauer, G. Starr, K.L. Jimenez. 2011. Controls on sensible heat and latent energy fluxes from a short-hydroperiod Florida Everglades marsh. Journal of Hydrology 411: 331-341. DOI: 10.1016/j.jhydrol.2011.10.014
Troxler, T., E.E. Gaiser, J.G. Barr, J.D. Fuentes, R. Jaffe, D.L. Childers, L. Collado-Vides, V.H. Rivera-Monroy, E. Castañeda-Moya, W.T. Anderson, R.M. Chambers, M. Chen, C. Coronado-Molina, S.E. Davis, V. Engel, C. Fitz, J.W. Fourqurean, T.A. Frankovich, J. Kominoski, C.J. Madden, S.L. Malone, S. Oberbauer, P.C. Olivas, J.H. Richards, C.J. Saunders, J. Schedlbauer, L.J. Scinto, F.H. Sklar, T.J. Smith, J.M. Smoak, G. Starr, R.R. Twilley, K.R.T. Whelan. 2013. Integrated carbon budget models for the Everglades terrestrial-coastal-oceanic gradient: current status and needs for inter-site comparisons. Oceanography 26: 98-107. DOI: 10.5670/oceanog.2013.51