HR: 17:00h
AN: B54A-04    [Abstracts]
TI: Monitoring Phenology by use of Digital Photography
AU: * Ahrends, H
EM: ahrends@giub.unibe.ch
AF: Institute of Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
AU: Stoeckli, R
EM: STOCKLI@env.ethz.ch
AF: Department of Atmospheric Science, Colorado State University, 200 West Lake Street, Fort Collins, 80523, United States
AU: Stoeckli, R
EM: STOCKLI@env.ethz.ch
AF: NASA Earth Observatory, Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, 20771, United States
AU: Stoeckli, R
EM: STOCKLI@env.ethz.ch
AF: Institute for Atmospheric and Climate Science, ETH Zurich, Universitaetsstrasse 16, Zuerich, 8092, Switzerland
AU: Eugster, W
EM: werner.eugster@ipw.agrl.ethz.ch
AF: Institute of Plant Sciences, ETH Zürich, Universitaetsstrasse 2, Zuerich, 8092, Switzerland
AU: Bruegger, R
EM: bruegger@giub.unibe.ch
AF: Institute of Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
AU: Wanner, H
EM: wanner@giub.unibe.ch
AF: Institute of Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
AU: Buchmann, N
EM: nina.buchmann@ipw.agrl.ethz.ch
AF: Institute of Plant Sciences, ETH Zürich, Universitaetsstrasse 2, Zuerich, 8092, Switzerland
AB: In recent decades phenology has become recognized as an important integrative method for assessing the impact of climate variability and climate change on ecosystems. Time series analysis of selected variables such as green-up, maturity, senescence and dormancy, yield valuable information about ecosystem responses to climate and are widely used in phenological, climatological and ecological models. Phenological ground observations are often observer-biased. Additionally, there is a significant decline in long- term observation sites that continue monitoring plant development due to missing volunteers for phenological field work. For two decades satellite remote sensing has been providing a global integrated view of vegetation phenological states. However this method still heavily depends on ground-based measurements for validation. Moreover, satellite images often have limited temporal and spatial coverage due to clouds, aerosols and other sensor-/platform-specific characteristics. Our project investigates the application of ground-based commercially available digital cameras in observational procedures and quality assurance of phenological monitoring. A standard digital camera (NIKON Coolpix 5400) was mounted on a flux tower at the Lägeren FLUXNET site (Switzerland), providing hourly digital images of a mixed forest. Parameter estimation of phenological stages is based on image statistics and red, green and blue channel colour brightness. Image analysis is conducted on regions of interest (ROI) of single tree species. Camera colour channel values are extracted and averaged across the ROI using daily time step. CO2-fluxes measured by eddy covariance and the phenological data from camera and satellite imagery are jointly analyzed. We anticipate that a network of digital cameras could provide inexpensive, spatially accurate and objective information with the required temporal resolution for phenological monitoring applications and ecosystem research. However, first it needs to be demonstrated that such automatic phenological algorithms are universally applicable and do not suffer from site-specific implicit assumptions.
DE: 0428 Carbon cycling (4806)
DE: 0434 Data sets
DE: 0476 Plant ecology (1851)
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: 2007 Fall Meeting