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| Titel |
Modeling light use efficiency in a subtropical mangrove forest equipped with CO2 eddy covariance |
| VerfasserIn |
J. G. Barr, V. Engel, J. D. Fuentes, D. O. Fuller, H. Kwon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-27), S.2145-2158 |
| Datensatznummer |
250018176
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| Publikation (Nr.) |
 copernicus.org/bg-10-2145-2013.pdf |
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| Zusammenfassung |
| Despite the importance of mangrove ecosystems in the global carbon budget,
the relationships between environmental drivers and carbon dynamics in these
forests remain poorly understood. This limited understanding is partly a
result of the challenges associated with in situ flux studies. Tower-based CO2
eddy covariance (EC) systems are installed in only a few mangrove forests
worldwide, and the longest EC record from the Florida Everglades contains
less than 9 years of observations. A primary goal of the present study was
to develop a methodology to estimate canopy-scale photosynthetic light use
efficiency in this forest. These tower-based observations represent a basis
for associating CO2 fluxes with canopy light use properties, and thus
provide the means for utilizing satellite-based reflectance data for
larger scale investigations. We present a model for mangrove canopy light
use efficiency utilizing the enhanced green vegetation index (EVI) derived
from the Moderate Resolution Imaging Spectroradiometer (MODIS) that is
capable of predicting changes in mangrove forest CO2 fluxes caused by a
hurricane disturbance and changes in regional environmental conditions,
including temperature and salinity. Model parameters are solved for in a
Bayesian framework. The model structure requires estimates of ecosystem
respiration (RE), and we present the first ever tower-based estimates
of mangrove forest RE derived from nighttime CO2 fluxes. Our
investigation is also the first to show the effects of salinity on mangrove
forest CO2 uptake, which declines 5% per each 10 parts per thousand
(ppt) increase in salinity. Light use efficiency in this forest declines
with increasing daily photosynthetic active radiation, which is an important
departure from the assumption of constant light use efficiency typically
applied in satellite-driven models. The model developed here provides a
framework for estimating CO2 uptake by these forests from reflectance
data and information about environmental conditions. |
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