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| Titel |
Digital imagery: a simple approach to study plant responses to drought |
| VerfasserIn |
H. E. Ahrends, S. Etzold, F. Jeanneret, W. Eugster, H. Wanner, N. Buchmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029076
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| Zusammenfassung |
| Different tree species show diverse responses to changing environmental conditions. Since
these responses give deeper insight in ecosystem functionality suitable observation
techniques are needed. Recent studies have demonstrated the successful application of digital
camera imagery for phenological monitoring in ecosystem studies. However, the use of daily
imagery from standard RGB cameras to observe species-specific responses of vegetation on
environmental impacts has not been tested yet. We therefore studied possibilities and
limitations of applying camera imagery of a mixed forest in the observation of tree-specific
responses to drought stress.
A digital camera was mounted on the uppermost platform of a fluxtower at the
CarboEurope site Lägeren (northern Switzerland). Since 2005 the camera provides
daily imagery of the forest canopy which is mainly consisting of beech and ash
trees. Based on the image color values a vegetation index was computed. Time
series of the vegetation index were jointly analyzed with meteorological data and
eddy covariance measurements of ecosystem carbon dioxide and water vapour
exchange.
Changing environmental conditions caused changes in the images color values, therefore
meteorological data and carbon dioxide exchange data were significantly correlated with the
index values. A drought period in early summer 2006 influenced index values for beech but
not for the highly drought-tolerant ash trees. We conclude that digital imagery provides a
cost-effective, nondestructive and objective technique to study species-specific vegetation
responses to drought stress and provide useful data that can be integrated in forest ecosystem
models. |
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