Petra D’Odorico


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Tracking the phenology of photosynthesis using carotenoid‐sensitive and near‐infrared reflectance vegetation indices in a temperate evergreen and mixed deciduous forest
Christopher Y. S. Wong, Petra D’Odorico, M. Altaf Arain, Ingo Ensminger
New Phytologist, Volume 226, Issue 6

Photosynthetic phenology is an important indicator of annual gross primary productivity (GPP). Assessing photosynthetic phenology remotely is difficult for evergreen conifers as they remain green year-round. Carotenoid-based vegetation indices such as the photochemical reflectance index (PRI) and chlorophyll/carotenoid index (CCI) are promising tools to remotely track the invisible phenology of photosynthesis by assessing carotenoid pigment dynamics. PRI, CCI and the near-infrared reflectance of vegetation (NIRV ) index may act as proxies of photosynthetic efficiency (ɛ), an important parameter in light-use efficiency models, or direct proxies of photosynthesis. To understand the physiological mechanisms reflected by PRI and CCI and the ability of vegetation indices to act as proxies of photosynthetic activity for estimating GPP, we measured leaf pigment composition, PRI, CCI, NIRV and photosynthetic activity at the leaf and canopy scales over 2 years in an evergreen and mixed deciduous forest. PRI and CCI captured the large seasonal carotenoid/chlorophyll ratio changes and good relationships were observed between PRI-ɛ and CCI-photosynthesis and NIRV -photosynthesis. PRI-, CCI- and NIRV -based models effectively tracked observed seasonal GPP. We propose that carotenoid-based and near-infrared reflectance vegetation indices may provide useful proxies of photosynthetic activity and can improve remote sensing-based models of GPP in evergreen and deciduous forests.


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Carotenoid based vegetation indices for accurate monitoring of the phenology of photosynthesis at the leaf-scale in deciduous and evergreen trees
Christopher Y. S. Wong, Petra D’Odorico, Yazad Bhathena, M. Altaf Arain, Ingo Ensminger
Remote Sensing of Environment, Volume 233

Abstract Carotenoid pigments play an important role in the seasonal regulation of photosynthesis and photoprotection of overwintering conifers. Because the seasonal changes in the rate of photosynthetic CO2 assimilation are linked to changes in carotenoid pigment composition, it has been suggested that carotenoid sensitive vegetation indices might be used to track the otherwise “invisible” phenology of photosynthesis of conifer forests through remote sensing of leaf spectral reflectance. In this study we aimed to assess differences in the seasonal regulation of photosynthesis and the associated variation of carotenoids and chlorophylls at the leaf-scale for eastern white pine, red maple and white oak, in order to understand if photosynthetic and photoprotective processes are adequately represented by different vegetation indices over the course of the year. For this purpose we measured maximum rates of CO2 assimilation (Amax), quantified photosynthetic pigments, estimated photochemical and non-photochemical quenching processes via chlorophyll fluorescence and determined leaf spectral reflectance in pine, maple and oak trees over the course of two years. Seasonal variation in Amax, used here as a proxy for photosynthetic phenology, and photosynthetic pigments were adequately represented by the normalized difference vegetation index (NDVI) for the deciduous trees. For pine, NDVI overestimated photosynthetic activity for most of the year and was hence not able to represent photosynthetic phenology, due to the fact that needle chlorophyll content shows only little variation over the course of the year. By contrast, using the photochemical reflectance index (PRI) and the chlorophyll/carotenoid index (CCI), which both detect variations in carotenoids, we were able to observe an improved representation of the seasonal variation of CO2 assimilation and photosynthetic phenology for the two deciduous and the conifer species. Based on the accurate detection of the seasonal regulation of leaf-scale photosynthetic activity for all three species, we conclude that carotenoid-sensitive vegetation indices are promising tools to improve monitoring of phenology in both deciduous and conifer forests.


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Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe’s terrestrial ecosystems: a review
Daniela Franz, Manuel Acosta, Núria Altimir, Nicola Arriga, Dominique Arrouays, Marc Aubinet, Mika Aurela, Edward Ayres, Ana López‐Ballesteros, Mireille Barbaste, Daniel Berveiller, Sébastien Biraud, Hakima Boukir, Thomas S. Brown, Christian Brümmer, Nina Buchmann, George Burba, Arnaud Carrara, A. Cescatti, Éric Ceschia, Robert Clement, Edoardo Cremonese, Patrick Crill, Eva Dařenová, Sigrid Dengel, Petra D’Odorico, Gianluca Filippa, Stefan Fleck, Gerardo Fratini, Roland Fuß, Bert Gielen, Sébastien Gogo, J. Grace, Alexander Graf, Achim Grelle, Patrick Gross, Thomas Grünwald, Sami Haapanala, Markus Hehn, Bernard Heinesch, Jouni Heiskanen, Mathias Herbst, Christine Herschlein, Lukas Hörtnagl, Koen Hufkens, Andreas Ibrom, Claudy Jolivet, Lilian Joly, Michael B. Jones, Ralf Kiese, Leif Klemedtsson, Natascha Kljun, Katja Klumpp, Pasi Kolari, Olaf Kolle, Andrew S. Kowalski, Werner L. Kutsch, Tuomas Laurila, Anne De Ligne, Sune Linder, Anders Lindroth, Annalea Lohila, Bernhard Longdoz, Ivan Mammarella, Tanguy Manise, Sara Marañón-Jiménez, Giorgio Matteucci, Matthias Mauder, Philip Meier, Lutz Merbold, Simone Mereu, Stefan Metzger, Mirco Migliavacca, Meelis Mölder, Leonardo Montagnani, Christine Moureaux, David D. Nelson, Eiko Nemitz, Giacomo Nicolini, Mats Nilsson, Maarten Op de Beeck, Bruce Osborne, Mikaell Ottosson Löfvenius, Marián Pavelka, Matthias Peichl, Olli Peltola, Mari Pihlatie, Andrea Pitacco, Radek Pokorný, Jukka Pumpanen, Céline Ratié, Corinna Rebmann, Marilyn Roland, Simone Sabbatini, Nicolas Saby, Matthew Saunders, Hans Peter Schmid, Marion Schrumpf, Pavel Sedlák, Penélope Serrano-Ortiz, Lukas Siebicke, Ladislav Šigut, Hanna Silvennoinen, Guillaume Simioni, Ute Skiba, Oliver Sonnentag, Kamel Soudani, Patrice Soulé, R. Steinbrecher, Tiphaine Tallec, Anne Thimonier, Eeva‐Stiina Tuittila, Juha‐Pekka Tuovinen, Patrik Vestin, Gaëlle Vincent, Caroline Vincke, Domenico Vitale, Peter Waldner, Per Weslien, Lisa Wingate, Georg Wohlfahrt, M. S. Zahniser, Timo Vesala
International Agrophysics, Volume 32, Issue 4

Abstract Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO 2 , CH 4 , N 2 O, H 2 O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.