Begin forwarded message: Date: February 21, 2011 9:36:56 AM EST
Subject: SEMINAR: REMINDER:GEOTOPICS Today: Dr. Engel (2/21 3:15 pm)
##### G E O T O P I
C S #####
P r e s e n t s
3:15 PM, Monday,
February 21st, 2011
SLAB Seminar Room, S/A 103
Refreshments 3:00 PM
Vic Engel
South
Florida Natural Resource
Center , Everglades National Park
"Mangrove Carbon Cycling in Western Everglades National
Park"
Net ecosystem carbon balance in an
Everglades tidal mangrove forest Mangrove forests exhibit high
global productivity rates estimated at 218±72 Tg C yr-1.
Dissolved and particulate carbon (C) fluxes generated by tidal
activity may represent up to 50% of net primary productivity in
these forests. Remarkably, mangrove forests have been estimated
to contribute 10% of all terrestrially derived dissolved organic
C to the oceans. However, direct measurements of tidal C
exchange in mangrove forests are challenging, particularly in
large deltaic systems where interconnected channels and
spatially-variable inundation patterns impute high levels of
uncertainty on traditional mass balance or flow-based
approaches. Improving estimates of tidal C fluxes in relation to
plant and soil C balance is necessary to gain a better
understanding of how mangrove ecosystems respond to
environmental forcings and to compare C balance in these systems
with values from terrestrial forests. Here we present a new
methodology for estimating ecosystem carbon balance and for
determining net C advection in a riverine mangrove forest. The
study site is located along the Shark River in Everglades
National Park, Florida, USA and is part of the AmeriFlux (site
SRK) and the Florida Coastal Everglades Long Term Ecological
Research (FCE-LTER) networks. Using an ecosystem-scale C balance
approach, C advection can be defined as the difference between
net ecosystem carbon dioxide exchange with the atmosphere (NEE)
and the net change in C measured in the plants and soil. Prior
to hurricane Wilma in 2005, NEE in this forest was estimated to
be greater than 1000 g C m-2 yr-1. Preliminary results suggest
that the C advected from the site annually may have been as high
as 300 g C m-2 yr-1 prior to the storm, increasing to as much as
800 g C m-2 yr-1 after the disturbance. Continuous measurements
of discharge rates and dissolved C in the main river channel
provide an independent estimate of tidal C advection over
seasonal time scales. Short-term, tracer-based analyses of
dissolved C conducted as part of this study add insight into
potential factors controlling the spatial and temporal
variability of tidal C fluxes. The C balance in this estuary is
governed by many of the same factors which regulate C in
terrestrial forests, including light and temperature, but also
by factors unique to tropical estuaries, including hydroperiod,
salinity, and disturbance caused by tropical storms and cold
temperatures. Improved understanding of the factors regulating
ecosystem carbon balance and organic soil accretion is of use to
Everglades managers responsible for the preservation of the
mangrove ecosystem in this era of sea level rise. Furthermore,
detailed coupling of land surface-atmosphere-water C fluxes will
enable more precise determinations of the role of mangrove
forests in global carbon budgets.
--
Cheers
Qiong Zhang
Marine Geology and Geophysics
Rosenstiel School of Marine and Atmospheric Science
University of Miami
4600 Rickenbacker Causeway
Miami Fl 33149
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