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ENVIRONMENTAL CONTROLS OVER NET EXCHANGES OF CARBON DIOXIDE FROM CONTRASTING FLORIDA ECOSYSTEMS
Author(s) -
Clark Kenneth L.,
Gholz Henry L.,
Moncrieff John B.,
Cropley Ford,
Loescher Henry W.
Publication year - 1999
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(1999)009[0936:econeo]2.0.co;2
Subject(s) - environmental science , cypress , ecosystem , evergreen , eddy covariance , wetland , deciduous , q10 , temperate climate , ecosystem respiration , ecology , growing season , hydrology (agriculture) , atmospheric sciences , botany , biology , respiration , geotechnical engineering , engineering , geology
Net CO 2 exchange estimated using eddy covariance and relaxed eddy accumulation indicated that evergreen pine upland and deciduous cypress wetland ecosystems in north‐central Florida had similar apparent light compensation points during the growing season (125 vs. 150 μmol PPFD·m −2 ·s −1 ), but that maximum rates at 1800 μmol PPFD·m −2 ·s −1 at the cypress ecosystem were only 59% of those at the pine ecosystem (8.9 vs. 15.2 μmol CO 2 ·m −2 ·s −1 ). During both the summer and winter months at the pine ecosystem, net CO 2 exchange in the daytime was a curvilinear function of PPFD, with no significant seasonal differences in slope or intercept. In contrast, net CO 2 exchange at the cypress ecosystem was minimal during the daytime in the winter. Net CO 2 exchange during the nighttime was an exponential function of air temperature at both sites, with Q 10 values of 2.0 and 1.9 for the pine and cypress ecosystems, respectively. Lower nighttime fluxes of CO 2 occurred at the cypress ecosystem across the entire temperature range. Both of these relatively sparse canopies stored CO 2 during stable atmospheric conditions. Mean maximum net CO 2 exchange during the daytime and mean nighttime net CO 2 exchange for these ecosystems were highly contrasting, and together resulted in a relatively low rate of annual carbon accumulation in the wetland when compared to the aggrading pine ecosystem. However, values reported here are within the ranges of values for other boreal, temperate, and tropical forest ecosystems.