Browsing by Subject "INTERANNUAL VARIABILITY"

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  • Yi, Chuixiang; Ricciuto, Daniel; Li, Runze; Wolbeck, John; Xu, Xiyan; Nilsson, Mats; Aires, Luis; Albertson, John D.; Ammann, Christof; Arain, M. Altaf; de Araujo, Alessandro C.; Aubinet, Marc; Aurela, Mika; Barcza, Zoltan; Barr, Alan; Berbigier, Paul; Beringer, Jason; Bernhofer, Christian; Black, Andrew T.; Bolstad, Paul V.; Bosveld, Fred C.; Broadmeadow, Mark S. J.; Buchmann, Nina; Burns, Sean P.; Cellier, Pierre; Chen, Jiquan; Ciais, Philippe; Clement, Robert; Cook, Bruce D.; Curtis, Peter S.; Dail, D. Bryan; Dellwik, Ebba; Delpierre, Nicolas; Desai, Ankur R.; Dore, Sabina; Dragoni, Danilo; Drake, Bert G.; Dufrene, Eric; Dunn, Allison; Elbers, Jan; Eugster, Werner; Falk, Matthias; Feigenwinter, Christian; Flanagan, Lawrence B.; Foken, Thomas; Frank, John; Fuhrer, Juerg; Gianelle, Damiano; Goldstein, Allen; Goulden, Mike; Granier, Andre; Gruenwald, Thomas; Gu, Lianhong; Guo, Haiqiang; Hammerle, Albin; Han, Shijie; Hanan, Niall P.; Haszpra, Laszlo; Heinesch, Bernard; Helfter, Carole; Hendriks, Dimmie; Hutley, Lindsay B.; Ibrom, Andreas; Jacobs, Cor; Johansson, Torbjoern; Jongen, Marjan; Katul, Gabriel; Kiely, Gerard; Klumpp, Katja; Knohl, Alexander; Kolb, Thomas; Kutsch, Werner L.; Lafleur, Peter; Laurila, Tuomas; Leuning, Ray; Lindroth, Anders; Liu, Heping; Loubet, Benjamin; Manca, Giovanni; Marek, Michal; Margolis, Hank A.; Martin, Timothy A.; Massman, William J.; Matamala, Roser; Matteucci, Giorgio; McCaughey, Harry; Merbold, Lutz; Meyers, Tilden; Migliavacca, Mirco; Miglietta, Franco; Misson, Laurent; Moelder, Meelis; Moncrieff, John; Monson, Russell K.; Montagnani, Leonardo; Montes-Helu, Mario; Moors, Eddy; Moureaux, Christine; Mukelabai, Mukufute M.; Munger, J. William; Myklebust, May; Nagy, Zoltan; Noormets, Asko; Oechel, Walter; Oren, Ram; Pallardy, Stephen G.; Kyaw, Tha Paw U.; Pereira, Joao S.; Pilegaard, Kim; Pinter, Krisztina; Pio, Casimiro; Pita, Gabriel; Powell, Thomas L.; Rambal, Serge; Randerson, James T.; von Randow, Celso; Rebmann, Corinna; Rinne, Janne; Rossi, Federica; Roulet, Nigel; Ryel, Ronald J.; Sagerfors, Jorgen; Saigusa, Nobuko; Sanz, Maria Jose; Mugnozza, Giuseppe-Scarascia; Schmid, Hans Peter; Seufert, Guenther; Siqueira, Mario; Soussana, Jean-Francois; Starr, Gregory; Sutton, Mark A.; Tenhunen, John; Tuba, Zoltan; Tuovinen, Juha-Pekka; Valentini, Riccardo; Vogel, Christoph S.; Wang, Shaoqiang; Wang, Weiguo; Welp, Lisa R.; Wen, Xuefa; Wharton, Sonia; Wilkinson, Matthew; Williams, Christopher A.; Wohlfahrt, Georg; Yamamoto, Susumu; Yu, Guirui; Zampedri, Roberto; Zhao, Bin; Zhao, Xinquan (2010)
  • Wang, T.; Ciais, P.; Piao, S. L.; Ottle, C.; Brender, P.; Maignan, F.; Arain, A.; Cescatti, A.; Gianelle, D.; Gough, C.; Gu, L.; Lafleur, P.; Laurila, T.; Marcolla, B.; Margolis, H.; Montagnani, L.; Moors, E.; Saigusa, N.; Vesala, T.; Wohlfahrt, G.; Koven, C.; Black, A.; Dellwik, E.; Don, A.; Hollinger, D.; Knohl, A.; Monson, R.; Munger, J.; Suyker, A.; Varlagin, A.; Verma, S. (2011)
  • Laine, A. M.; Mehtätalo, L.; Tolvanen, A.; Frolking, S.; Tuittila, E-S (2019)
    Northern wetlands with organic soil i.e., mires are significant carbon storages. This key ecosystem service may be threatened by anthropogenic activities and climate change, yet we still lack a consensus on how these major changes affects their carbon sink capacities. We studied how forestry drainage and restoration combined with experimental warming, impacts greenhouse gas fluxes of wetlands with peat. We measured CO2 and CH4 during two and N2O fluxes during one growing season using the chamber method. Gas fluxes were primarily controlled by water table, leaf area and temperature. Land use had a clear impact of on CO2 exchange. Forestry drainage increased respiration rates and decreased field layer net ecosystem CO2 uptake (NEE) and leaf area index (LAI), while at restoration sites the flux rates and LAI had recovered to the level of undrained sites. CH4 emissions were exceptionally low at all sites during our study years due to natural drought, but still somewhat lower at drained compared to undrained sites. Moderate warming triggered an increase in LAI across all land use types. This was accompanied by an increase in cumulative seasonal NEE. Restoration appeared to be an effective tool to return the ecosystem functions of these wetlands as we found no differences in LAI or any gas flux components (PMAX, Reco, NEE, CH4 or N2O) between restored and undrained sites. We did not find any signs that moderate warming would compromise the return of the ecosystem functions related to C sequestration. (C) 2018 Elsevier B.V. All rights reserved.
  • Spilling, Kristian; Camarena-Gómez, Maria-Teresa; Lipsewers, Tobias; Martinez-Varela, Alícia; Díaz-Rosas, Francisco; Eronen-Rasimus, Eeva; Silva, Nelson; von Dassow, Peter; Montecino, Vivian (2019)
    The ratio of inorganic nitrogen to phosphorus (NP) is projected to decrease in the Eastern Boundary Upwelling Systems (EBUS) due to warming of the surface waters. In an enclosure experiment, we employed two levels of inorganic NP ratios (10 and 5) for three distinct plankton communities collected along the coast of central Chile (33°S). The primary effect of the NP treatment was related to different concentrations of NO3, which directly influenced the biomass of phytoplankton. In addition, low inorganic NP ratio reduced the seston NP and Chl a-C ratios, and there were some effects on the plankton community composition, e.g., benefitting Synechococcus spp. in some communities. One of the communities was clearly top-down controlled and trophic transfer to grazers was up to 5.8% during the 12 day experiment. Overall, the initial, natural plankton community composition was more important for seston stoichiometry and trophic transfer than the manipulation of the inorganic NP ratio, highlighting the importance of plankton community structure for marine ecosystem functioning.
  • Alekseychik, Pavel; Mammarella, Ivan; Karpov, Dmitry; Dengel, Sigrid; Terentieva, Irina; Sabrekov, Alexander; Glagolev, Mikhail; Lapshina, Elena (2017)
    Very few studies of ecosystem-atmosphere exchange involving eddy covariance data have been conducted in Siberia, with none in the western Siberian middle taiga. This work provides the first estimates of carbon dioxide (CO2) and energy budgets in a typical bog of the western Siberian middle taiga based on May-August measurements in 2015. The footprint of measured fluxes consisted of a homogeneous mixture of tree-covered ridges and hollows with the vegetation represented by typical sedges and shrubs. Generally, the surface exchange rates resembled those of pinecovered bogs elsewhere. The surface energy balance closure approached 100 %. Net CO2 uptake was comparatively high, summing up to CO2 gCm(-2) for the four measurement months, while the Bowen ratio was seasonally stable at 28 %. The ecosystem turned into a net CO2 source during several front passage events in June and July. The periods of heavy rain helped keep the water table at a sustainably high level, preventing a usual drawdown in summer. However, because of the cloudy and rainy weather, the observed fluxes might rather represent the special weather conditions of 2015 than their typical magnitudes.
  • Qiu, Chunjing; Zhu, Dan; Ciais, Philippe; Guenet, Bertrand; Krinner, Gerhard; Peng, Shushi; Aurela, Mika; Bernhofer, Christian; Bruemmer, Christian; Bret-Harte, Syndonia; Chu, Housen; Chen, Jiquan; Desai, Ankur R.; Dusek, Jiri; Euskirchen, Eugenie S.; Fortuniak, Krzysztof; Flanagan, Lawrence B.; Friborg, Thomas; Grygoruk, Mateusz; Gogo, Sebastien; Gruenwald, Thomas; Hansen, Birger U.; Holl, David; Humphreys, Elyn; Hurkuck, Miriam; Kiely, Gerard; Klatt, Janina; Kutzbach, Lars; Largeron, Chloe; Laggoun-Defarge, Fatima; Lund, Magnus; Lafleur, Peter M.; Li, Xuefei; Mammarella, Ivan; Merbold, Lutz; Nilsson, Mats B.; Olejnik, Janusz; Ottosson-Lofvenius, Mikaell; Oechel, Walter; Parmentier, Frans-Jan W.; Peichl, Matthias; Pirk, Norbert; Peltola, Olli; Pawlak, Wlodzimierz; Rasse, Daniel; Rinne, Janne; Shaver, Gaius; Schmid, Hans Peter; Sottocornola, Matteo; Steinbrecher, Rainer; Sachs, Torsten; Urbaniak, Marek; Zona, Donatella; Ziemblinska, Klaudia (2018)
    Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5 degrees grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (V-cmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r(2) = 0.76; Nash-Sutcliffe modeling efficiency, MEF = 0.76) and ecosystem respiration (ER, r(2) = 0.78, MEF = 0.75), with lesser accuracy for latent heat fluxes (LE, r(2) = 0.42, MEF = 0.14) and and net ecosystem CO2 exchange (NEE, r(2) = 0.38, MEF = 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r(2) values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r(2) values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r(2) <0.1), likely due to the uncertain water input to the peat from surrounding areas. However, the poor performance of WT simulation did not greatly affect predictions of ER and NEE. We found a significant relationship between optimized V-cmax and latitude (temperature), which better reflects the spatial gradients of annual NEE than using an average V-cmax value.
  • Foken, Thomas; Babel, Wolfgang; Munger, J. William; Gronholm, Tiia; Vesala, Timo; Knohl, Alexander (2021)
    Extensive studies are available that analyse time series of carbon dioxide and water flux measurements of FLUXNET sites over many years and link these results to climate change such as changes in atmospheric carbon dioxide concentration, air temperature and growing season length and other factors. Many of the sites show trends to a larger carbon uptake. Here we analyse time series of net ecosystem exchange, gross primary production, respiration, and evapotranspiration of four forest sites with particularly long measurement periods of about 20 years. The regular trends shown are interrupted by periods with higher or lower increases of carbon uptake. These breakpoints can be of very different origin and include forest decline, increased vegetation period, drought effects, heat waves, and changes in site heterogeneity. The influence of such breakpoints should be included in long-term studies of land-atmosphere exchange processes.
  • Alekseychik, P.; Mammarella, I.; Lindroth, A.; Lohila, A.; Aurela, M.; Laurila, T.; Kasurinen, V.; Lund, M.; Rinne, J.; Nilsson, M. B.; Peichl, M.; Minkkinen, K.; Shurpali, N. J.; Tuittila, E.-S.; Martikainen, P. J.; Tuovinen, J.-P.; Vesala, T. (2018)
    Surface-atmosphere energy exchange is strongly ecosystem-specific. At the same time, as the energy balance constitutes responses of an ecosystem to environmental stressors including precipitation, humidity and solar radiation, it results in feedbacks of potential importance for the regional climate. Northern peatlands represent a diverse class of ecosystems that cover nearly 6 x 10(6) km(2) in the Boreal region, which makes the inter-comparison of their energy balances an important objective. With this in mind we studied energy exchange across a broad spectrum of peatlands from pristine fens and bogs to forested and agriculturally managed peatlands, which represent a large fraction of the landscape in Finland and Sweden. The effects of management activities on the energy balance were extensively examined from the micrometeorological point of view, using eddy covariance data from eight sites in these two countries (56 degrees 12'-62 degrees 11' N, 13 degrees 03'-30 degrees 05' E). It appears that the surface energy balance varies widely amongst the different peatland types. Generally, energy exchange features including the Bowen ratio, surface conductance, coupling to the atmosphere, responses to water table fluctuations and vapour pressure deficit could be associated directly with the peatland type. The relative constancy of the Bowen ratio in natural open mires contrasted with its variation in tree-covered and agricultural peatlands. We conclude that the impacts of management and the consequences of land-use change in peatlands for the local and regional climate might be substantial.
  • Park, Sung-Bin; Knohl, Alexander; Migliavacca, Mirco; Thum, Tea; Vesala, Timo; Peltola, Olli; Mammarella, Ivan; Prokushkin, Anatoly; Kolle, Olaf; Lavric, Jost; Park, Sang Seo; Heimann, Martin (2021)
    Climate change impacts the characteristics of the vegetation carbon-uptake process in the northern Eurasian terrestrial ecosystem. However, the currently available direct CO2 flux measurement datasets, particularly for central Siberia, are insufficient for understanding the current condition in the northern Eurasian carbon cycle. Here, we report daily and seasonal interannual variations in CO2 fluxes and associated abiotic factors measured using eddy covariance in a coniferous forest and a bog near Zotino, Krasnoyarsk Krai, Russia, for April to early June, 2013-2017. Despite the snow not being completely melted, both ecosystems became weak net CO2 sinks if the air temperature was warm enough for photosynthesis. The forest became a net CO2 sink 7-16 days earlier than the bog. After the surface soil temperature exceeded similar to 1 degrees C, the ecosystems became persistent net CO2 sinks. Net ecosystem productivity was highest in 2015 for both ecosystems because of the anomalously high air temperature in May compared with other years. Our findings demonstrate that long-term monitoring of flux measurements at the site level, particularly during winter and its transition to spring, is essential for understanding the responses of the northern Eurasian ecosystem to spring warming.
  • Rinne, Janne; Tuittila, Eeva-Stiina; Peltola, Olli; Li, Xuefei; Raivonen, Maarit; Alekseychik, Pavel; Haapanala, Sami; Pihlatie, Mari; Aurela, Mika; Mammarella, Ivan; Vesala, Timo (2018)
    We have analyzed decade-long methane flux data set from a boreal fen, Siikaneva, together with data on environmental parameters and carbon dioxide exchange. The methane flux showed seasonal cycle but no systematic diel cycle. The highest fluxes were observed in July-August with average value of 73 nmol m(-2) s(-1). Wintertime fluxes were small but positive, with January-March average of 6.7 nmol m(-2) s(-1). Daily average methane emission correlated best with peat temperatures at 20-35 cm depths. The second highest correlation was with gross primary production (GPP). The best correspondence between emission algorithm and measured fluxes was found for a variable-slope generalized linear model (r(2) = 0.89) with peat temperature at 35 cm depth and GPP as explanatory variables, slopes varying between years. The homogeneity of slope approach indicated that seasonal variation explained 79% of the sum of squares variation of daily average methane emission, the interannual variation in explanatory factors 7.0%, functional change 5.3%, and random variation 9.1%. Significant correlation between interannual variability of growing season methane emission and that of GPP indicates that on interannual time scales GPP controls methane emission variability, crucially for development of process-based methane emission models. Annual methane emission ranged from 6.0 to 14 gC m(-2) and was 2.7 +/- 0.4% of annual GPP. Over 10-year period methane emission was 18% of net ecosystem exchange as carbon. The weak relation of methane emission to water table position indicates that space-to-time analogy, used to extrapolate spatial chamber data in time, may not be applicable in seasonal time scales.
  • Pastorello, Gilberto; Trotta, Carlo; Canfora, Eleonora; Chu, Housen; Christianson, Danielle; Cheah, You-Wei; Poindexter, Cristina; Chen, Jiquan; Elbashandy, Abdelrahman; Humphrey, Marty; Isaac, Peter; Polidori, Diego; Ribeca, Alessio; van Ingen, Catharine; Zhang, Leiming; Amiro, Brian; Ammann, Christof; Arain, M. Altaf; Ardo, Jonas; Arkebauer, Timothy; Arndt, Stefan K.; Arriga, Nicola; Aubinet, Marc; Aurela, Mika; Baldocchi, Dennis; Barr, Alan; Beamesderfer, Eric; Marchesini, Luca Belelli; Bergeron, Onil; Beringer, Jason; Bernhofer, Christian; Berveiller, Daniel; Billesbach, Dave; Black, Thomas Andrew; Blanken, Peter D.; Bohrer, Gil; Boike, Julia; Bolstad, Paul V.; Bonal, Damien; Bonnefond, Jean-Marc; Bowling, David R.; Bracho, Rosvel; Brodeur, Jason; Bruemmer, Christian; Buchmann, Nina; Burban, Benoit; Burns, Sean P.; Buysse, Pauline; Cale, Peter; Cavagna, Mauro; Cellier, Pierre; Chen, Shiping; Chini, Isaac; Christensen, Torben R.; Cleverly, James; Collalti, Alessio; Consalvo, Claudia; Cook, Bruce D.; Cook, David; Coursolle, Carole; Cremonese, Edoardo; Curtis, Peter S.; D'Andrea, Ettore; da Rocha, Humberto; Dai, Xiaoqin; Davis, Kenneth J.; De Cinti, Bruno; de Grandcourt, Agnes; De Ligne, Anne; De Oliveira, Raimundo C.; Delpierre, Nicolas; Desai, Ankur R.; Di Bella, Carlos Marcelo; di Tommasi, Paul; Dolman, Han; Domingo, Francisco; Dong, Gang; Dore, Sabina; Duce, Pierpaolo; Dufrene, Eric; Dunn, Allison; Dusek, Jiri; Eamus, Derek; Eichelmann, Uwe; ElKhidir, Hatim Abdalla M.; Eugster, Werner; Ewenz, Cacilia M.; Ewers, Brent; Famulari, Daniela; Fares, Silvano; Feigenwinter, Iris; Feitz, Andrew; Fensholt, Rasmus; Filippa, Gianluca; Fischer, Marc; Frank, John; Galvagno, Marta; Gharun, Mana; Gianelle, Damiano; Gielen, Bert; Gioli, Beniamino; Gitelson, Anatoly; Goded, Ignacio; Goeckede, Mathias; Goldstein, Allen H.; Gough, Christopher M.; Goulden, Michael L.; Graf, Alexander; Griebel, Anne; Gruening, Carsten; Gruenwald, Thomas; Hammerle, Albin; Han, Shijie; Han, Xingguo; Hansen, Birger Ulf; Hanson, Chad; Hatakka, Juha; He, Yongtao; Hehn, Markus; Heinesch, Bernard; Hinko-Najera, Nina; Hoertnagl, Lukas; Hutley, Lindsay; Ibrom, Andreas; Ikawa, Hiroki; Jackowicz-Korczynski, Marcin; Janous, Dalibor; Jans, Wilma; Jassal, Rachhpal; Jiang, Shicheng; Kato, Tomomichi; Khomik, Myroslava; Klatt, Janina; Knohl, Alexander; Knox, Sara; Kobayashi, Hideki; Koerber, Georgia; Kolle, Olaf; Kosugi, Yoshiko; Kotani, Ayumi; Kowalski, Andrew; Kruijt, Bart; Kurbatova, Julia; Kutsch, Werner L.; Kwon, Hyojung; Launiainen, Samuli; Laurila, Tuomas; Law, Bev; Leuning, Ray; Li, Yingnian; Liddell, Michael; Limousin, Jean-Marc; Lion, Marryanna; Liska, Adam J.; Lohila, Annalea; Lopez-Ballesteros, Ana; Lopez-Blanco, Efren; Loubet, Benjamin; Loustau, Denis; Lucas-Moffat, Antje; Lueers, Johannes; Ma, Siyan; Macfarlane, Craig; Magliulo, Vincenzo; Maier, Regine; Mammarella, Ivan; Manca, Giovanni; Marcolla, Barbara; Margolis, Hank A.; Marras, Serena; Massman, William; Mastepanov, Mikhail; Matamala, Roser; Matthes, Jaclyn Hatala; Mazzenga, Francesco; McCaughey, Harry; McHugh, Ian; McMillan, Andrew M. S.; Merbold, Lutz; Meyer, Wayne; Meyers, Tilden; Miller, Scott D.; Minerbi, Stefano; Moderow, Uta; Monson, Russell K.; Montagnani, Leonardo; Moore, Caitlin E.; Moors, Eddy; Moreaux, Virginie; Moureaux, Christine; Munger, J. William; Nakai, Taro; Neirynck, Johan; Nesic, Zoran; Nicolini, Giacomo; Noormets, Asko; Northwood, Matthew; Nosetto, Marcelo; Nouvellon, Yann; Novick, Kimberly; Oechel, Walter; Olesen, Jorgen Eivind; Ourcival, Jean-Marc; Papuga, Shirley A.; Parmentier, Frans-Jan; Paul-Limoges, Eugenie; Pavelka, Marian; Peichl, Matthias; Pendall, Elise; Phillips, Richard P.; Pilegaard, Kim; Pirk, Norbert; Posse, Gabriela; Powell, Thomas; Prasse, Heiko; Prober, Suzanne M.; Rambal, Serge; Rannik, Ullar; Raz-Yaseef, Naama; Reed, David; de Dios, Victor Resco; Restrepo-Coupe, Natalia; Reverter, Borja R.; Roland, Marilyn; Sabbatini, Simone; Sachs, Torsten; Saleska, Scott R.; Sanchez-Canete, Enrique P.; Sanchez-Mejia, Zulia M.; Schmid, Hans Peter; Schmidt, Marius; Schneider, Karl; Schrader, Frederik; Schroder, Ivan; Scott, Russell L.; Sedlak, Pavel; Serrano-Ortiz, Penelope; Shao, Changliang; Shi, Peili; Shironya, Ivan; Siebicke, Lukas; Sigut, Ladislav; Silberstein, Richard; Sirca, Costantino; Spano, Donatella; Steinbrecher, Rainer; Stevens, Robert M.; Sturtevant, Cove; Suyker, Andy; Tagesson, Torbern; Takanashi, Satoru; Tang, Yanhong; Tapper, Nigel; Thom, Jonathan; Tiedemann, Frank; Tomassucci, Michele; Tuovinen, Juha-Pekka; Urbanski, Shawn; Valentini, Riccardo; van der Molen, Michiel; van Gorsel, Eva; van Huissteden, Ko; Varlagin, Andrej; Verfaillie, Joseph; Vesala, Timo; Vincke, Caroline; Vitale, Domenico; Vygodskaya, Natalia; Walker, Jeffrey P.; Walter-Shea, Elizabeth; Wang, Huimin; Weber, Robin; Westermann, Sebastian; Wille, Christian; Wofsy, Steven; Wohlfahrt, Georg; Wolf, Sebastian; Woodgate, William; Li, Yuelin; Zampedri, Roberto; Zhang, Junhui; Zhou, Guoyi; Zona, Donatella; Agarwal, Deb; Biraud, Sebastien; Torn, Margaret; Papale, Dario (2020)
    The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.
  • Gea-Izquierdo, Guillermo; Bergeron, Yves; Huang, Jian-Guo; Lapointe-Garant, Marie-Pierre; Grace, John; Berninger, Frank (2014)
  • Vihma, Timo; Uotila, Petteri; Sandven, Stein; Pozdnyakov, Dmitry; Makshtas, Alexander; Pelyasov, Alexander; Pirazzini, Roberta; Danielsen, Finn; Chalov, Sergey; Lappalainen, Hanna K.; Ivanov, Vladimir; Frolov, Ivan; Albin, Anna; Cheng, Bin; Dobrolyubov, Sergey; Arkhipkin, Viktor; Myslenkov, Stanislav; Petäjä, Tuukka; Kulmala, Markku (2019)
    The Arctic marine climate system is changing rapidly, which is seen in the warming of the ocean and atmosphere, decline of sea ice cover, increase in river discharge, acidification of the ocean, and changes in marine ecosystems. Socio-economic activities in the coastal and marine Arctic are simultaneously changing. This calls for the establishment of a marine Arctic component of the Pan-Eurasian Experiment (MA-PEEX). There is a need for more in situ observations on the marine atmosphere, sea ice, and ocean, but increasing the amount of such observations is a pronounced technological and logistical challenge. The SMEAR (Station for Measuring Ecosystem-Atmosphere Relations) concept can be applied in coastal and archipelago stations, but in the Arctic Ocean it will probably be more cost-effective to further develop a strongly distributed marine observation network based on autonomous buoys, moorings, autonomous underwater vehicles (AUVs), and unmanned aerial vehicles (UAVs). These have to be supported by research vessel and aircraft campaigns, as well as various coastal observations, including community-based ones. Major manned drift-ing stations may occasionally be comparable to terrestrial SMEAR flagship stations. To best utilize the observations, atmosphere-ocean reanalyses need to be further developed. To well integrate MA-PEEX with the existing terrestrialatmospheric PEEX, focus is needed on the river discharge and associated fluxes, coastal processes, and atmospheric transports in and out of the marine Arctic. More observations and research are also needed on the specific socioeconomic challenges and opportunities in the marine and coastal Arctic, and on their interaction with changes in the climate and environmental system. MA-PEEX will promote international collaboration; sustainable marine meteorological, sea ice, and oceanographic observations; advanced data management; and multidisciplinary research on the marine Arctic and its interaction with the Eurasian continent.
  • Franz, Daniela; Acosta, Manuel; Altimir, Nuria; Arriga, Nicola; Arrouays, Dominique; Aubinet, Marc; Aurela, Mika; Ayres, Edward; Lopez-Ballesteros, Ana; Barbaste, Mireille; Berveiller, Daniel; Biraud, Sebastien; Boukir, Hakima; Brown, Timothy; Bruemmer, Christian; Buchmann, Nina; Burba, George; Carrara, Arnaud; Cescatti, Allessandro; Ceschia, Eric; Clement, Robert; Cremonese, Edoardo; Crill, Patrick; Darenova, Eva; Dengel, Sigrid; D'Odorico, Petra; Filippa, Gianluca; Fleck, Stefan; Fratini, Gerardo; Fuss, Roland; Gielen, Bert; Gogo, Sebastien; Grace, John; Graf, Alexander; Grelle, Achim; Gross, Patrick; Gruenwald, Thomas; Haapanala, Sami; Hehn, Markus; Heinesch, Bernard; Heiskanen, Jouni; Herbst, Mathias; Herschlein, Christine; Hortnagl, Lukas; Hufkens, Koen; Ibrom, Andreas; Jolivet, Claudy; Joly, Lilian; Jones, Michael; Kiese, Ralf; Klemedtsson, Leif; Kljun, Natascha; Klumpp, Katja; Kolari, Pasi; Kolle, Olaf; Kowalski, Andrew; Kutsch, Werner; Laurila, Tuomas; de Ligne, Anne; Linder, Sune; Lindroth, Anders; Lohila, Annalea; Longdoz, Bernhard; Mammarella, Ivan; Manise, Tanguy; Maranon Jimenez, Sara; Matteucci, Giorgio; Mauder, Matthias; Meier, Philip; Merbold, Lutz; Mereu, Simone; Metzger, Stefan; Migliavacca, Mirco; Molder, Meelis; Montagnani, Leonardo; Moureaux, Christine; Nelson, David; Nemitz, Eiko; Nicolini, Giacomo; Nilsson, Mats B.; Op de Beeck, Maarten; Osborne, Bruce; Lofvenius, Mikaell Ottosson; Pavelka, Marian; Peichl, Matthias; Peltola, Olli; Pihlatie, Mari; Pitacco, Andrea; Pokorny, Radek; Pumpanen, Jukka; Ratie, Celine; Rebmann, Corinna; Roland, Marilyn; Sabbatini, Simone; Saby, Nicolas P. A.; Saunders, Matthew; Schmid, Hans Peter; Schrumpf, Marion; Sedlak, Pavel; Serrano Ortiz, Penelope; Siebicke, Lukas; Sigut, Ladislav; Silvennoinen, Hanna; Simioni, Guillaume; Skiba, Ute; Sonnentag, Oliver; Soudani, Kamel; Soule, Patrice; Steinbrecher, Rainer; Tallec, Tiphaine; Thimonier, Anne; Tuittila, Eeva-Stiina; Tuovinen, Juha-Pekka; Vestin, Patrik; Vincent, Gaelle; Vincke, Caroline; Vitale, Domenico; Waldner, Peter; Weslien, Per; Wingate, Lisa; Wohlfahrt, Georg; Zahniser, Mark; Vesala, Timo (2018)
    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.
  • Haeni, M.; Zweifel, R.; Eugster, W.; Gessler, A.; Zielis, S.; Bernhofer, C.; Carrara, A.; Gruenwald, T.; Havrankova, K.; Heinesch, B.; Herbst, M.; Ibrom, A.; Knohl, A.; Lagergren, F.; Law, B. E.; Marek, M.; Matteucci, G.; McCaughey, J. H.; Minerbi, S.; Montagnani, L.; Moors, E.; Olejnik, J.; Pavelka, M.; Pilegaard, K.; Pita, G.; Rodrigues, A.; Sanz Sanchez, M. J.; Schelhaas, M. -J.; Urbaniak, M.; Valentini, R.; Varlagin, A.; Vesala, T.; Vincke, C.; Wu, J.; Buchmann, N. (2017)
    Accurate predictions of net ecosystem productivity (NEPc) of forest ecosystems are essential for climate change decisions and requirements in the context of national forest growth and greenhouse gas inventories. However, drivers and underlying mechanisms determining NEPc (e.g., climate and nutrients) are not entirely understood yet, particularly when considering the influence of past periods. Here we explored the explanatory power of the compensation day (cDOY)defined as the day of year when winter net carbon losses are compensated by spring assimilationfor NEPc in 26 forests in Europe, North America, and Australia, using different NEPc integration methods. We found cDOY to be a particularly powerful predictor for NEPc of temperate evergreen needleleaf forests (R-2=0.58) and deciduous broadleaf forests (R-2=0.68). In general, the latest cDOY correlated with the lowest NEPc. The explanatory power of cDOY depended on the integration method for NEPc, forest type, and whether the site had a distinct winter net respiratory carbon loss or not. The integration methods starting in autumn led to better predictions of NEPc from cDOY then the classical calendar method starting 1 January. Limited explanatory power of cDOY for NEPc was found for warmer sites with no distinct winter respiratory loss period. Our findings highlight the importance of the influence of winter processes and the delayed responses of previous seasons' climatic conditions on current year's NEPc. Such carry-over effects may contain information from climatic conditions, carbon storage levels, and hydraulic traits of several years back in time.