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EFFECTS OF METEOROLOGICAL VARIATIONS ON THE CO 2 EXCHANGE OF A BRAZILIAN TRANSITIONAL TROPICAL FOREST
Author(s) -
Vourlitis George L.,
Priante Filho Nicolau,
Hayashi Mauro M. S.,
Nogueira José de S.,
Raiter Fernando,
Hoegel Wander,
Campelo, Jr José Holanda
Publication year - 2004
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 - 10.1890/01-6005
Subject(s) - environmental science , eddy covariance , canopy , atmospheric sciences , microclimate , ecosystem , biometeorology , vapour pressure deficit , ecosystem respiration , leaf area index , forest ecology , tree canopy , ecology , transpiration , photosynthesis , biology , botany , geology
The net ecosystem CO 2 exchange (NEE) of a 28–30 m tall transitional (ecotonal) tropical forest of the Brazilian Amazon was quantified using tower‐based eddy covariance. Measurements were made between August 1999 and July 2001 and were used to develop nonlinear statistical models to assess daily variations in ecophysiological parameters and provide annual estimates of NEE, gross ecosystem CO 2 exchange (GEE), and respiration ( R e ). Diurnal trends in NEE were correlated with variations in photosynthetic photon flux density ( Q ), vapor pressure deficit ( V ), and temperature. Seasonal trends in the CO 2 ‐flux components estimated from nonlinear regression ( A max and R 0 ) were highly correlated with soil water availability and canopy structural properties (LAI and litter production). These results suggest that variations in soil water content can affect rates of canopy photosynthesis and whole forest respiration by altering both physiological processes and canopy structural properties. Estimates of the annual NEE suggest that the forest was in balance with respect to CO 2 during the study period, which, in terms of rainfall, was a relatively typical period compared to the 30‐yr average rainfall regime. Our results also suggest that the warmer and dryer microclimate and decline in LAI that accompany land‐cover change will cause transitional forests to be sources of CO 2 to the atmosphere.