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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.

Open access

Sigrid Dengel, Alexander Graf, Thomas Grünwald, Markus Hehn, Pasi Kolari, Mikaell Ottosson Löfvenius, Lutz Merbold, Giacomo Nicolini and Marian Pavelka

Abstract

Precipitation is one of the most important abiotic variables related to plant growth. Using standardised measurements improves the comparability and quality of precipitation data as well as all other data within the Integrated Carbon Observation System network. Despite the spatial and temporal variation of some types of precipitation, a single point measurement satisfies the requirement as an ancillary variable for eddy covariance measurements. Here the term precipitation includes: rain, snowfall (liquid water equivalent) and snow depth, with the latter two being of interest only where occurring. Weighing gauges defined as Integrated Carbon Observation System standard with the capacity of continuously measuring liquid and solid precipitation are installed free-standing, away from obstacles obstructing rain or snowfall. In order to minimise wind-induced errors, gauges are shielded either naturally or artificially to reduce the adverse effect of wind speed on the measurements. Following standardised methods strengthens the compatibility and comparability of data with other standardised environmental observation networks while opening the possibility for synthesis studies of different precipitation measurement methodologies and types including a wide range of ecosystems and geolocations across Europe.

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

Marian Pavelka, Manuel Acosta, Ralf Kiese, Núria Altimir, Christian Brümmer, Patrick Crill, Eva Darenova, Roland Fuß, Bert Gielen, Alexander Graf, Leif Klemedtsson, Annalea Lohila, Bernhard Longdoz, Anders Lindroth, Mats Nilsson, Sara Maraňón Jiménez, Lutz Merbold, Leonardo Montagnani, Matthias Peichl, Mari Pihlatie, Jukka Pumpanen, Penelope Serrano Ortiz, Hanna Silvennoinen, Ute Skiba, Patrik Vestin, Per Weslien, Dalibor Janous and Werner Kutsch

Abstract

Chamber measurements of trace gas fluxes between the land surface and the atmosphere have been conducted for almost a century. Different chamber techniques, including static and dynamic, have been used with varying degrees of success in estimating greenhouse gases (CO2, CH4, N2O) fluxes. However, all of these have certain disadvantages which have either prevented them from providing an adequate estimate of greenhouse gas exchange or restricted them to be used under limited conditions. Generally, chamber methods are relatively low in cost and simple to operate. In combination with the appropriate sample allocations, chamber methods are adaptable for a wide variety of studies from local to global spatial scales, and they are particularly well suited for in situ and laboratory-based studies. Consequently, chamber measurements will play an important role in the portfolio of the Pan-European long-term research infrastructure Integrated Carbon Observation System. The respective working group of the Integrated Carbon Observation System Ecosystem Monitoring Station Assembly has decided to ascertain standards and quality checks for automated and manual chamber systems instead of defining one or several standard systems provided by commercial manufacturers in order to define minimum requirements for chamber measurements. The defined requirements and recommendations related to chamber measurements are described here.

Open access

Dominique Arrouays, Nicolas P.A. Saby, Hakima Boukir, Claudy Jolivet, Céline Ratié, Marion Schrumpf, Lutz Merbold, Bert Gielen, Sébastien Gogo, Nicolas Delpierre, Gaëlle Vincent, Katja Klumpp and Denis Loustau

Abstract

There is an urgent need for standardized monitoring of existing soil organic carbon stocks in order to accurately quantify potential negative or positive feedbacks with climate change on carbon fluxes. Given the uncertainty of flux measurements at the ecosystem scale, obtaining precise estimates of changes in soil organic carbon stocks is essential to provide an independent assessment of long-term net ecosystem carbon exchange. Here we describe the standard procedure to monitor the soil organic carbon stocks within the footprint of an eddy covariance flux tower, as applied at ecosystem stations of the Integrated Carbon Observation System. The objectives are i) to ensure comparability between sites and to be able to draw general conclusions from the results obtained across many ecosystems and ii) to optimize the sampling design in order to be able to prove changes in time using a reduced number of samples. When sampling a given site at two periods, the objective is generally to assess if changes occurred in time. The changes that can be detected (i.e., demonstrated as statistically significant) depend on several parameters such as the number of samples, the spatial sampling design, and the inherent within-site soil variability. Depending on these parameters, one can define the ‘minimum detectable change’ which is the minimum value of changed that can be statistically proved. Using simulation studies, we address the trade-off between increasing the number of samples and getting lower minimum detectable changes of soil organic carbon stocks.

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

Denis Loustau, Nuria Altimir, Mireille Barbaste, Bert Gielen, Sara Marańón Jiménez, Katja Klumpp, Sune Linder, Giorgio Matteucci, Lutz Merbold, Marteen Op de Beek, Patrice Soulé, Anne Thimonier, Caroline Vincke and Peter Waldner

Abstract

The nutritional status of plant canopies in terms of nutrients (C, N, P, K, Ca, Mg, Mn, Fe, Cu, Zn) exerts a strong influence on the carbon cycle and energy balance of terrestrial ecosystems. Therefore, in order to account for the spatial and temporal variations in nutritional status of the plant species composing the canopy, we detail the methodology applied to achieve consistent time-series of leaf mass to area ratio and nutrient content of the foliage within the footprint of the Integrated Carbon Observation System Ecosystem stations. The guidelines and defi-nitions apply to most terrestrial ecosystems.

Open access

Arnaud Carrara, Pasi Kolari, Maarten Op de Beeck, Nicola Arriga, Daniel Berveiller, Sigrid Dengel, Andreas Ibrom, Lutz Merbold, Corinna Rebmann, Simone Sabbatini, Penelope Serrano-Ortíz and Sébastien C. Biraud

Abstract

Solar radiation is a key driver of energy and carbon fluxes in natural ecosystems. Radiation measurements are essential for interpreting ecosystem scale greenhouse gases and energy fluxes as well as many other observations performed at ecosystem stations of the Integrated Carbon Observation System (ICOS). We describe and explain the relevance of the radiation variables that are monitored continuously at ICOS ecosystem stations and define recommendations to perform these measurements with consistent and comparable accuracy. The measurement methodology and instruments are described including detailed technical specifications. Guidelines for instrumental set up as well as for operation, maintenance and data collection are defined considering both ICOS scientific objectives and practical operational constraints. For measurements of short-wave (solar) and long wave (infrared) radiation components, requirements for the ICOS network are based on available well-defined state-of-the art standards (World Meteorological Organization, International Organization for Standardization). For photosynthetically active radiation measurements, some basic instrumental requirements are based on the performance of commercially available sensors. Since site specific conditions and practical constraints at individual ICOS ecosystem stations may hamper the applicability of standard requirements, we recommend that ICOS develops mid-term coordinated actions to assess the effective level of uncertainties in radiation measurements at the network scale.

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

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.