Wingate, L., Ogee, J., Cremonese, E., Filippa, G., Mizunuma, T., Migliavacca, M., Moisy, C., Wilkinson, M., Moureaux, C., Wohlfahrt, G., Hammerle, A., Hoertnagl, L., Gimeno, C., Porcar-Castell, A., Galvagno, M., Nakaji, T., Morison, J., Kolle, O., Knohl, A., Kutsch, W., Kolari, P., Nikinmaa, E., Ibrom, A., Gielen, B., Eugster, W., Balzarolo, M., Papale, D., Klumpp, K., Koestner, B., Gruenwald, T., Joffre, R., Ourcival, J. -M., Hellstrom, M., Lindroth, A., George, C., Longdoz, B., Genty, B., Levula, J., Heinesch, B., Sprintsin, M., Yakir, D., Manise, T., Guyon, D., Ahrends, H., Plaza-Aguilar, A., Guan, J. H. and Grace, J. (2015). Interpreting canopy development and physiology using a European phenology camera network at flux sites. Biogeosciences, 12 (20). S. 5995 - 6016. GOTTINGEN: COPERNICUS GESELLSCHAFT MBH. ISSN 1726-4189

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Abstract

Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and their response to climate and management practices are crudely represented in land surface models. As visual observations of phenology are laborious, there is a need to supplement long-term observations with automated techniques such as those provided by digital repeat photography at high temporal and spatial resolution. We present the first synthesis from a growing observational network of digital cameras installed on towers across Europe above deciduous and evergreen forests, grasslands and croplands, where vegetation and atmosphere CO2 fluxes are measured continuously. Using colour indices from digital images and using piecewise regression analysis of time series, we explored whether key changes in canopy phenology could be detected automatically across different land use types in the network. The piecewise regression approach could capture the start and end of the growing season, in addition to identifying striking changes in colour signals caused by flowering and management practices such as mowing. Exploring the dates of green-up and senescence of deciduous forests extracted by the piecewise regression approach against dates estimated from visual observations, we found that these phenological events could be detected adequately (RMSE < 8 and 11 days for leaf out and leaf fall, respectively). We also investigated whether the seasonal patterns of red, green and blue colour fractions derived from digital images could be modelled mechanistically using the PROSAIL model parameterised with information of seasonal changes in canopy leaf area and leaf chlorophyll and carotenoid concentrations. From a model sensitivity analysis we found that variations in colour fractions, and in particular the late spring 'green hump' observed repeatedly in deciduous broadleaf canopies across the network, are essentially dominated by changes in the respective pigment concentrations. Using the model we were able to explain why this spring maximum in green signal is often observed out of phase with the maximum period of canopy photosynthesis in ecosystems across Europe. Coupling such quasi-continuous digital records of canopy colours with co-located CO2 flux measurements will improve our understanding of how changes in growing season length are likely to shape the capacity of European ecosystems to sequester CO2 in the future.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Wingate, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ogee, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Cremonese, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Filippa, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mizunuma, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Migliavacca, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Moisy, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wilkinson, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Moureaux, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wohlfahrt, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hammerle, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hoertnagl, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gimeno, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Porcar-Castell, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Galvagno, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Nakaji, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Morison, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kolle, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Knohl, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kutsch, W.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kolari, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Nikinmaa, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ibrom, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gielen, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eugster, W.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Balzarolo, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Papale, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Klumpp, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Koestner, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gruenwald, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Joffre, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ourcival, J. -M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hellstrom, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lindroth, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
George, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Longdoz, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Genty, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Levula, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Heinesch, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sprintsin, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Yakir, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Manise, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Guyon, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ahrends, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Plaza-Aguilar, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Guan, J. H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Grace, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-415776
DOI: 10.5194/bg-12-5995-2015
Journal or Publication Title: Biogeosciences
Volume: 12
Number: 20
Page Range: S. 5995 - 6016
Date: 2015
Publisher: COPERNICUS GESELLSCHAFT MBH
Place of Publication: GOTTINGEN
ISSN: 1726-4189
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
DIGITAL REPEAT PHOTOGRAPHY; NET CARBON UPTAKE; SOIL-TEMPERATURE; SCOTS PINE; ECOSYSTEM RESPIRATION; CHLOROPHYLL CONTENT; FOREST PHENOLOGY; DECIDUOUS FOREST; LEAF CHLOROPHYLL; DIOXIDE UPTAKEMultiple languages
Ecology; Geosciences, MultidisciplinaryMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/41577

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