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  • Author: Lukas Hörtnagl x
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Open access

Koen Hufkens, Gianluca Filippa, Edoardo Cremonese, Mirco Migliavacca, Petra D’Odorico, Matthias Peichl, Bert Gielen, Lukas Hörtnagl, Kamel Soudani, Dario Papale, Corinna Rebmann, Tim Brown and Lisa Wingate

Abstract

The presence or absence of leaves within plant canopies exert a strong influence on the carbon, water and energy balance of ecosystems. Identifying key changes in the timing of leaf elongation and senescence during the year can help to understand the sensitivity of different plant functional types to changes in temperature. When recorded over many years these data can provide information on the response of ecosystems to long-term changes in climate. The installation of digital cameras that take images at regular intervals of plant canopies across the Integrated Carbon Observation System ecosystem stations will provide a reliable and important record of variations in canopy state, colour and the timing of key phenological events. Here, we detail the procedure for the implementation of cameras on Integrated Carbon Observation System flux towers and how these images will help us understand the impact of leaf phenology and ecosystem function, distinguish changes in canopy structure from leaf physiology and at larger scales will assist in the validation of (future) remote sensing products. These data will help us improve the representation of phenological responses to climatic variability across Integrated Carbon Observation System stations and the terrestrial biosphere through the improvement of model algorithms and the provision of validation datasets.

Open access

Simone Sabbatini, Ivan Mammarella, Nicola Arriga, Gerardo Fratini, Alexander Graf, Lukas Hörtnagl, Andreas Ibrom, Bernard Longdoz, Matthias Mauder, Lutz Merbold, Stefan Metzger, Leonardo Montagnani, Andrea Pitacco, Corinna Rebmann, Pavel Sedlák, Ladislav Šigut, Domenico Vitale and Dario Papale

Abstract

The eddy covariance is a powerful technique to estimate the surface-atmosphere exchange of different scalars at the ecosystem scale. The EC method is central to the ecosystem component of the Integrated Carbon Observation System, a monitoring network for greenhouse gases across the European Continent. The data processing sequence applied to the collected raw data is complex, and multiple robust options for the different steps are often available. For Integrated Carbon Observation System and similar networks, the standardisation of methods is essential to avoid methodological biases and improve comparability of the results. We introduce here the steps of the processing chain applied to the eddy covariance data of Integrated Carbon Observation System stations for the estimation of final CO2, water and energy fluxes, including the calculation of their uncertainties. The selected methods are discussed against valid alternative options in terms of suitability and respective drawbacks and advantages. The main challenge is to warrant standardised processing for all stations in spite of the large differences in e.g. ecosystem traits and site conditions. The main achievement of the Integrated Carbon Observation System eddy covariance data processing is making CO2 and energy flux results as comparable and reliable as possible, given the current micrometeorological understanding and the generally accepted state-of-the-art processing methods.

Open access

Maarten Op de Beeck, Bert Gielen, Lutz Merbold, Edward Ayres, Penelope Serrano-Ortiz, Manuel Acosta, Marian Pavelka, Leonardo Montagnani, Mats Nilsson, Leif Klemedtsson, Caroline Vincke, Anne De Ligne, Christine Moureaux, Sara Marańon-Jimenez, Matthew Saunders, Simone Mereu and Lukas Hörtnagl

Abstract

The Integrated Carbon Observation System is a pan-European research infrastructure providing standardized, long-term observations of greenhouse gas concentrations and earth-atmosphere greenhouse gas interactions. The terrestrial component of Integrated Carbon Observation System comprises a network of monitoring stations in terrestrial ecosystems where the principal activity is the measurement of ecosystem-atmosphere fluxes of greenhouse gases and energy by means of the eddy covariance technique. At each station a large set of ancillary variables needed for the interpretation of observed fluxes and for process studies is additionally monitored. This set includes a subset of variables that describe the thermal and moisture conditions of the soil and which are here conveniently referred to as soil-meteorological variables: soil temperature, volumetric soil water content, water table depth, and soil heat flux density. This paper describes the standard methodology that has been developped for the monitoring of these variables at the ecosystem stations.

Open access

Matthew Saunders, Sigrid Dengel, Pasi Kolari, Christine Moureaux, Leonardo Montagnani, Eric Ceschia, Nuria Altimir, Ana López-Ballesteros, Sara Marańon-Jimenez, Manuel Acosta, Katja Klumpp, Bert Gielen, Maarten Op de Beeck, Lukas Hörtnagl, Lutz Merbold, Bruce Osborne, Thomas Grünwald, Dominique Arrouays, Hakima Boukir, Nicolas Saby, Giacomo Nicolini, Dario Papale and Michael Jones

Abstract

There are many factors that influence ecosystem scale carbon, nitrogen and greenhouse gas dynamics, including the inherent heterogeneity of soils and vegetation, anthropogenic management interventions, and biotic and abiotic disturbance events. It is important therefore, to document the characteristics of the soils and vegetation and to accurately report all management activities, and disturbance events to aid the interpretation of collected data, and to determine whether the ecosystem either amplifies or mitigates climate change. This paper outlines the importance of assessing both the spatial and temporal variability of soils and vegetation and to report all management events, the import or export of C or N from the ecosystem, and the occurrence of biotic/abiotic disturbances at ecosystem stations of the Integrated Carbon Observation System, a pan-European research infrastructure.

Open access

Eiko Nemitz, Ivan Mammarella, Andreas Ibrom, Mika Aurela, George G. Burba, Sigrid Dengel, Bert Gielen, Achim Grelle, Bernard Heinesch, Mathias Herbst, Lukas Hörtnagl, Leif Klemedtsson, Anders Lindroth, Annalea Lohila, Dayle K. McDermitt, Philip Meier, Lutz Merbold, David Nelson, Giacomo Nicolini, Mats B. Nilsson, Olli Peltola, Janne Rinne and Mark Zahniser

Abstract

Commercially available fast-response analysers for methane (CH4) and nitrous oxide (N2O) have recently become more sensitive, more robust and easier to operate. This has made their application for long-term flux measurements with the eddy-covariance method more feasible. Unlike for carbon dioxide (CO2) and water vapour (H2O), there have so far been no guidelines on how to optimise and standardise the measurements. This paper reviews the state-of-the-art of the various steps of the measurements and discusses aspects such as instrument selection, setup and maintenance, data processing as well as the additional measurements needed to aid interpretation and gap-filling. It presents the methodological protocol for eddy covariance measurements of CH4 and N2O fluxes as agreed for the ecosystem station network of the pan-European Research Infrastructure Integrated Carbon Observation System and provides a first international standard that is suggested to be adopted more widely. Fluxes can be episodic and the processes controlling the fluxes are complex, preventing simple mechanistic gap-filling strategies. Fluxes are often near or below the detection limit, requiring additional care during data processing. The protocol sets out the best practice for these conditions to avoid biasing the results and long-term budgets. It summarises the current approach to gap-filling.

Open access

Bert Gielen, Manuel Acosta, Nuria Altimir, Nina Buchmann, Alessandro Cescatti, Eric Ceschia, Stefan Fleck, Lukas Hörtnagl, Katja Klumpp, Pasi Kolari, Annalea Lohila, Denis Loustau, Sara Marańon-Jimenez, Tanguy Manise, Giorgio Matteucci, Lutz Merbold, Christine Metzger, Christine Moureaux, Leonardo Montagnani, Mats B. Nilsson, Bruce Osborne, Dario Papale, Marian Pavelka, Matthew Saunders, Guillaume Simioni, Kamel Soudani, Oliver Sonnentag, Tiphaine Tallec, Eeva-Stiina Tuittila, Matthias Peichl, Radek Pokorny, Caroline Vincke and Georg Wohlfahrt

Abstract

The Integrated Carbon Observation System is a Pan-European distributed research infrastructure that has as its main goal to monitor the greenhouse gas balance of Europe. The ecosystem component of Integrated Carbon Observation System consists of a multitude of stations where the net greenhouse gas exchange is monitored continuously by eddy covariance measurements while, in addition many other measurements are carried out that are a key to an understanding of the greenhouse gas balance. Amongst them are the continuous meteorological measurements and a set of non-continuous measurements related to vegetation. The latter include Green Area Index, aboveground biomass and litter biomass. The standardized methodology that is used at the Integrated Carbon Observation System ecosystem stations to monitor these vegetation related variables differs between the ecosystem types that are represented within the network, whereby in this paper we focus on forests, grasslands, croplands and mires. For each of the variables and ecosystems a spatial and temporal sampling design was developed so that the variables can be monitored in a consistent way within the ICOS network. The standardisation of the methodology to collect Green Area Index, above ground biomass and litter biomass and the methods to evaluate the quality of the collected data ensures that all stations within the ICOS ecosystem network produce data sets with small and similar errors, which allows for inter-comparison comparisons across the Integrated Carbon Observation System ecosystem network.

Open access

Corinna Rebmann, Marc Aubinet, HaPe Schmid, Nicola Arriga, Mika Aurela, George Burba, Robert Clement, Anne De Ligne, Gerardo Fratini, Bert Gielen, John Grace, Alexander Graf, Patrick Gross, Sami Haapanala, Mathias Herbst, Lukas Hörtnagl, Andreas Ibrom, Lilian Joly, Natascha Kljun, Olaf Kolle, Andrew Kowalski, Anders Lindroth, Denis Loustau, Ivan Mammarella, Matthias Mauder, Lutz Merbold, Stefan Metzger, Meelis Mölder, Leonardo Montagnani, Dario Papale, Marian Pavelka, Matthias Peichl, Marilyn Roland, Penélope Serrano-Ortiz, Lukas Siebicke, Rainer Steinbrecher, Juha-Pekka Tuovinen, Timo Vesala, Georg Wohlfahrt and Daniela Franz

Abstract

The Integrated Carbon Observation System Research Infrastructure aims to provide long-term, continuous observations of sources and sinks of greenhouse gases such as carbon dioxide, methane, nitrous oxide, and water vapour. At ICOS ecosystem stations, the principal technique for measurements of ecosystem-atmosphere exchange of GHGs is the eddy-covariance technique. The establishment and setup of an eddy-covariance tower have to be carefully reasoned to ensure high quality flux measurements being representative of the investigated ecosystem and comparable to measurements at other stations. To fulfill the requirements needed for flux determination with the eddy-covariance technique, variations in GHG concentrations have to be measured at high frequency, simultaneously with the wind velocity, in order to fully capture turbulent fluctuations. This requires the use of high-frequency gas analysers and ultrasonic anemometers. In addition, to analyse flux data with respect to environmental conditions but also to enable corrections in the post-processing procedures, it is necessary to measure additional abiotic variables in close vicinity to the flux measurements. Here we describe the standards the ICOS ecosystem station network has adopted for GHG flux measurements with respect to the setup of instrumentation on towers to maximize measurement precision and accuracy while allowing for flexibility in order to observe specific ecosystem features.

Open access

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, Timothy Brown, Christian Brümmer, Nina Buchmann, George Burba, Arnaud Carrara, Allessandro Cescatti, Eric Ceschia, Robert Clement, Edoardo Cremonese, Patrick Crill, Eva Darenova, Sigrid Dengel, Petra D’Odorico, Gianluca Filippa, Stefan Fleck, Gerardo Fratini, Roland Fuß, Bert Gielen, Sébastien Gogo, John 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 Jones, Ralf Kiese, Leif Klemedtsson, Natascha Kljun, Katja Klumpp, Pasi Kolari, Olaf Kolle, Andrew Kowalski, Werner Kutsch, Tuomas Laurila, Anne de Ligne, Sune Linder, Anders Lindroth, Annalea Lohila, Bernhard Longdoz, Ivan Mammarella, Tanguy Manise, Sara Maraňón Jiménez, Giorgio Matteucci, Matthias Mauder, Philip Meier, Lutz Merbold, Simone Mereu, Stefan Metzger, Mirco Migliavacca, Meelis Mölder, Leonardo Montagnani, Christine Moureaux, David Nelson, Eiko Nemitz, Giacomo Nicolini, Mats B. Nilsson, Maarten Op de Beeck, Bruce Osborne, Mikaell Ottosson Löfvenius, Marian Pavelka, Matthias Peichl, Olli Peltola, Mari Pihlatie, Andrea Pitacco, Radek Pokorný, Jukka Pumpanen, Céline Ratié, Corinna Rebmann, Marilyn Roland, Simone Sabbatini, Nicolas P.A. Saby, Matthew Saunders, Hans Peter Schmid, Marion Schrumpf, Pavel Sedlák, Penelope Serrano Ortiz, Lukas Siebicke, Ladislav Šigut, Hanna Silvennoinen, Guillaume Simioni, Ute Skiba, Oliver Sonnentag, Kamel Soudani, Patrice Soulé, Rainer 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, Mark Zahniser and Timo Vesala

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; CO2, CH4, N2O, H2O) 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.