Quantitative phenological observations of a mixed beech forest in northern Switzerland with digital photography
| Autor: | Robert Brügger, Heinz Wanner, François Jeanneret, Jürg Schenk, Pavel Michna, Reto Stöckli, Hella Ellen Ahrends, Werner Eugster |
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| Rok vydání: | 2008 |
| Předmět: |
Atmospheric Science
business.product_category Soil Science Climate change Aquatic Science Oceanography FluxNet Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Beech Uncertainty analysis Earth-Surface Processes Water Science and Technology Digital camera Remote sensing Ecology biology Phenology Paleontology Digital photography Forestry biology.organism_classification Geophysics Space and Planetary Science Temporal resolution Environmental science business |
| Zdroj: | Journal of Geophysical Research: Biogeosciences. 113 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/2007jg000650 |
| Popis: | [1] Vegetation phenology has a strong influence on the timing and phase of global terrestrial carbon and water exchanges and is an important indicator of climate change and variability. In this study we tested the application of inexpensive digital visible-light cameras in monitoring phenology. A standard digital camera was mounted on a 45 m tall flux tower at the Lageren FLUXNET/CarboEuropeIP site (Switzerland), providing hourly images of a mixed beech forest. Image analysis was conducted separately on a set of regions of interest representing two different tree species during spring in 2005 and 2006. We estimated the date of leaf emergence based on the levels of the extracted red, green and blue colors. Comparisons with validation data were in accordance with the phenology of the observed trees. The mean error of observed leaf unfolding dates compared with validation data was 3 days in 2005 and 3.6 days in 2006. An uncertainty analysis was performed and demonstrated moderate impacts on color values of changing illumination conditions due to clouds and illumination angles. We conclude that digital visible-light cameras could provide inexpensive, spatially representative and objective information with the required temporal resolution for phenological studies. |
| Databáze: | OpenAIRE |
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