Florida Coastal Everglades Long Term Ecological Research
Untitled Document


PAST WORKING GROUPS

Climate and Disturbance Cross-Cutting Theme
(Phase II, 2007-2012)


Abstract:
Climatic change exerts strong controls on biophysical dynamics in the coastal Everglades, regardless of changes in freshwater delivery. Decadal, global phenomena affect precipitation patterns in south Florida at several temporal scales. El Niño events,for example, reduce the wet-dry seasonality in precipitation without typically affecting total annual rainfall (Childers et al. 2006). Such changes in intra-annual rainfall patterns affect the volume and timing of surface and groundwater flow, and wetland hydroperiods. Decreased hydroperiods increase the risk of fire (Lockwood et al. 2003). Sea level is increasing at about 2.5 mm yr-1 in south Florida (Zervas, 2001), and predictions of a doubling of this rate by 2100 would increase mean sea level at FCE by nearly 40 cm (Toscano and Macintyre, 2003). At even current rates, sea level rise will have major long-term impacts on the FCE landscape since virtually all of ENP is below 1.5 m above sea level (Titus and Richman, 2001). Some predictions hold that mangrove wetlands in much of the Caribbean will be able to maintain themselves against sea level rise, at least for the next 50 to 100 years (Ellison and Farnsworth, 1997). This prediction is contentious, though. During FCE II, we will continue documenting long-term changes in the size and location of the oligohaline ecotone as the landscape responds to sea level rise, hurricanes, increased freshwater inflows, and fire. We expect that, over intermediate time scales (years to decades), the first two drivers will tend to force the estuarine boundary of the ecotone landward while the latter 2 drivers will either force the freshwater boundary seaward or hold it near its current location. In the long term, though (decades to a century), marine forces will prevail and the entire ecotone will transgress landward. Nutrient inputs and the degree of oligotrophy will likely complicate this spatial dynamic in ways that aren?t easily predicted?particularly as these biogeochemical controls affect peat accumulation rates in ecotone wetlands, which ultimately determine vertical sustainability of these systems in a rising sea level environment.

The Climate and Disturbance Working Group is new to the FCE organizational structure and after the 2007 ASM, we presented our immediate research goals for the next year. These goals including securing supplemental funding for LIDAR transects to be flown and processed for all FCE sites. Submission of supplemental funding request to NSF were approved for LIDAR (Zhang and Anderson, FIU) and for a disturbance study of the mangrove ecotone to evaluate the effects of Hurricane Wilma (Rivera-Monroy, LSU). Additionally, the repairs are now complete to the eddy-flux tower deployed at SRS-6, which was severely damaged during Hurricane Wilma in 2005. Two additional flux towers will be deployed at stations TS1 and SRS 2 by Oberbauer (FIU) with funding from DOE NICCR. Other members of the working group are extremely active. We will also continue to document vertical soil dynamics by measuring soil elevation change and surficial accretion by continuing our soil elevation table (SET) work at sites in the SRS ecotone K.Whelan & T.Smith; USGS; (Whelan et al., 2005) and the TS/Ph ecotone (F.Sklar & C. Coronado-Molina, SFWMD). Finally, we will continue to reconstruct historical changes in hydroperiod across the coastal Everglades using sedimentological (Saunders et al. 2006) and isotope-dendrological methods (Anderson et al., 2005). We will relate these records to existing teleconnection indices (NAO, NAtl, ENSO and PNA) to investigate long-term relationships between global climatic drivers and biophysical dynamics at the FCE LTER (Enfield and Alfaro, 1999; Rosenheim et al., 2005; Tan and Neelin, 2004).
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National Science Foundation logo This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DEB-1237517, #DBI-0620409, and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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