Integrated carbon budget models for the Everglades terrestrial-coastal-oceanic gradient: Current status and needs for inter-site comparisons

Recent studies suggest that coastal ecosystems can bury significantly
more C than tropical forests, indicating that continued coastal development and
exposure to sea level rise and storms will have global biogeochemical consequences.
The Florida Coastal Everglades Long Term Ecological Research (FCE LTER) site
provides an excellent subtropical system for examining carbon (C) balance because
of its exposure to historical changes in freshwater distribution and sea level rise and
its history of significant long-term carbon-cycling studies. FCE LTER scientists used
net ecosystem C balance and net ecosystem exchange data to estimate C budgets
for riverine mangrove, freshwater marsh, and seagrass meadows, providing insights
into the magnitude of C accumulation and lateral aquatic C transport. Rates of net
C production in the riverine mangrove forest exceeded those reported for many
tropical systems, including terrestrial forests, but there are considerable uncertainties
around those estimates due to the high potential for gain and loss of C through
aquatic fluxes. C production was approximately balanced between gain and loss in
Everglades marshes; however, the contribution of periphyton increases uncertainty
in these estimates. Moreover, while the approaches used for these initial estimates
were informative, a resolved approach for addressing areas of uncertainty is critically
needed for coastal wetland ecosystems. Once resolved, these C balance estimates,
in conjunction with an understanding of drivers and key ecosystem feedbacks, can
inform cross-system studies of ecosystem response to long-term changes in climate,
hydrologic management, and other land use along coastlines