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| Titel |
Reviews and Syntheses: optical sampling of the flux tower footprint |
| VerfasserIn |
J. A. Gamon |
| 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 ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-30), S.4509-4523 |
| Datensatznummer |
250118042
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| Publikation (Nr.) |
 copernicus.org/bg-12-4509-2015.pdf |
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| Zusammenfassung |
| The purpose of this review is to address the reasons and methods for
conducting optical remote sensing within the flux tower footprint.
Fundamental principles and conclusions gleaned from over 2 decades of
proximal remote sensing at flux tower sites are reviewed. The organizing
framework used here is the light-use efficiency (LUE) model, both because it
is widely used, and because it provides a useful theoretical construct for
integrating optical remote sensing with flux measurements. Multiple ways of
driving this model, ranging from meteorological measurements to remote
sensing, have emerged in recent years, making it a convenient conceptual
framework for comparative experimental studies. New interpretations of
established optical sampling methods, including the photochemical reflectance
index (PRI) and solar-induced chlorophyll fluorescence (SIF), are discussed
within the context of the LUE model. Multi-scale analysis across temporal and
spatial axes is a central theme because such scaling can provide links
between ecophysiological mechanisms detectable at the level of individual
organisms and broad patterns emerging at larger scales, enabling evaluation
of emergent properties and extrapolation to the flux footprint and beyond.
Proper analysis of the sampling scale requires an awareness of sampling
context that is often essential to the proper interpretation of optical
signals. Additionally, the concept of optical types, vegetation exhibiting
contrasting optical behavior in time and space, is explored as a way to frame
our understanding of the controls on surface–atmosphere fluxes.
Complementary normalized difference vegetation index (NDVI) and PRI patterns
across ecosystems are offered as an example of this hypothesis, with the LUE
model and light-response curve providing an integrating framework. I conclude
that experimental approaches allowing systematic exploration of plant optical
behavior in the context of the flux tower network provides a unique way to
improve our understanding of environmental constraints and ecophysiological
function. In addition to an enhanced mechanistic understanding of ecosystem
processes, this integration of remote sensing with flux measurements offers
many rich opportunities for upscaling, satellite validation, and informing
practical management objectives ranging from assessing ecosystem health and
productivity to quantifying biospheric carbon sequestration. |
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