Articles | Volume 21, issue 15
https://doi.org/10.5194/bg-21-3571-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-21-3571-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
13 Aug 2024
Research article |
| 13 Aug 2024
| 13 Aug 2024
Compound soil and atmospheric drought (CSAD) events and CO2 fluxes of a mixed deciduous forest: the occurrence, impact, and temporal contribution of main drivers
Liliana Scapucci
CORRESPONDING AUTHOR
Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
Ankit Shekhar
Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
Sergio Aranda-Barranco
Department of Ecology, University of Granada, Granada, Spain
Anastasiia Bolshakova
University of Natural Resources and Life Sciences Vienna (BOKU), Vienna, Austria
Lukas Hörtnagl
Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
Mana Gharun
Faculty of Geosciences, University of Münster, Münster, Germany
Nina Buchmann
Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland
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Yi Wang, Iris Feigenwinter, Lukas Hörtnagl, Anna K. Gilgen, and Nina Buchmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-3562, https://doi.org/10.5194/egusphere-2025-3562, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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Our study shows that managed grasslands can maintain stable CO2 uptake despite rising temperature and declining soil moisture. Using 20 years of data from a Swiss grassland, we found that light, temperature, and management strongly influenced the ecosystem CO2 exchange. During summer droughts, low soil moisture limited plant growth, but smart management choices helped buffer these effects. This suggests that even small, well-timed actions can support climate resilience in agriculture.
Mana Gharun, Ankit Shekhar, Lukas Hörtnagl, Luana Krebs, Nicola Arriga, Mirco Migliavacca, Marilyn Roland, Bert Gielen, Leonardo Montagnani, Enrico Tomelleri, Ladislav Šigut, Matthias Peichl, Peng Zhao, Marius Schmidt, Thomas Grünwald, Mika Korkiakoski, Annalea Lohila, and Nina Buchmann
Biogeosciences, 22, 1393–1411, https://doi.org/10.5194/bg-22-1393-2025, https://doi.org/10.5194/bg-22-1393-2025, 2025
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The effect of winter warming on forest CO2 fluxes has rarely been investigated. We tested the effect of the warm winter of 2020 on the forest CO2 fluxes across 14 sites in Europe and found that the net ecosystem productivity (NEP) across most sites declined during the warm winter due to increased respiration fluxes.
Sergio Aranda-Barranco, Penélope Serrano-Ortiz, Andrew S. Kowalski, and Enrique P. Sánchez-Cañete
SOIL, 11, 213–232, https://doi.org/10.5194/soil-11-213-2025, https://doi.org/10.5194/soil-11-213-2025, 2025
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This study investigated soil respiration and the main factors involved in a semi-arid environment (olive grove). For this purpose, 1 year's worth of automatic multi-chamber measurements was used, accompanied by ecosystem respiration data obtained using the eddy covariance technique. The soil respiration annual balance, Q10 parameter, rain pulses, and spatial and temporal variability of soil respiration are presented in this paper.
Mana Gharun, Ankit Shekhar, Jingfeng Xiao, Xing Li, and Nina Buchmann
Biogeosciences, 21, 5481–5494, https://doi.org/10.5194/bg-21-5481-2024, https://doi.org/10.5194/bg-21-5481-2024, 2024
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In 2022, Europe's forests faced unprecedented dry conditions. Our study aimed to understand how different forest types respond to extreme drought. Using meteorological data and satellite imagery, we compared 2022 with two previous extreme years, 2003 and 2018. Despite less severe drought in 2022, forests showed a 30 % greater decline in photosynthesis compared to 2018 and 60 % more than 2003. This suggests an alarming level of vulnerability of forests across Europe to more frequent droughts.
Jacob A. Nelson, Sophia Walther, Fabian Gans, Basil Kraft, Ulrich Weber, Kimberly Novick, Nina Buchmann, Mirco Migliavacca, Georg Wohlfahrt, Ladislav Šigut, Andreas Ibrom, Dario Papale, Mathias Göckede, Gregory Duveiller, Alexander Knohl, Lukas Hörtnagl, Russell L. Scott, Jiří Dušek, Weijie Zhang, Zayd Mahmoud Hamdi, Markus Reichstein, Sergio Aranda-Barranco, Jonas Ardö, Maarten Op de Beeck, Dave Billesbach, David Bowling, Rosvel Bracho, Christian Brümmer, Gustau Camps-Valls, Shiping Chen, Jamie Rose Cleverly, Ankur Desai, Gang Dong, Tarek S. El-Madany, Eugenie Susanne Euskirchen, Iris Feigenwinter, Marta Galvagno, Giacomo A. Gerosa, Bert Gielen, Ignacio Goded, Sarah Goslee, Christopher Michael Gough, Bernard Heinesch, Kazuhito Ichii, Marcin Antoni Jackowicz-Korczynski, Anne Klosterhalfen, Sara Knox, Hideki Kobayashi, Kukka-Maaria Kohonen, Mika Korkiakoski, Ivan Mammarella, Mana Gharun, Riccardo Marzuoli, Roser Matamala, Stefan Metzger, Leonardo Montagnani, Giacomo Nicolini, Thomas O'Halloran, Jean-Marc Ourcival, Matthias Peichl, Elise Pendall, Borja Ruiz Reverter, Marilyn Roland, Simone Sabbatini, Torsten Sachs, Marius Schmidt, Christopher R. Schwalm, Ankit Shekhar, Richard Silberstein, Maria Lucia Silveira, Donatella Spano, Torbern Tagesson, Gianluca Tramontana, Carlo Trotta, Fabio Turco, Timo Vesala, Caroline Vincke, Domenico Vitale, Enrique R. Vivoni, Yi Wang, William Woodgate, Enrico A. Yepez, Junhui Zhang, Donatella Zona, and Martin Jung
Biogeosciences, 21, 5079–5115, https://doi.org/10.5194/bg-21-5079-2024, https://doi.org/10.5194/bg-21-5079-2024, 2024
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The movement of water, carbon, and energy from the Earth's surface to the atmosphere, or flux, is an important process to understand because it impacts our lives. Here, we outline a method called FLUXCOM-X to estimate global water and CO2 fluxes based on direct measurements from sites around the world. We go on to demonstrate how these new estimates of net CO2 uptake/loss, gross CO2 uptake, total water evaporation, and transpiration from plants compare to previous and independent estimates.
Ihab Alfadhel, Ignacio Peralta-Maraver, Isabel Reche, Enrique P. Sánchez-Cañete, Sergio Aranda-Barranco, Eva Rodríguez-Velasco, Andrew S. Kowalski, and Penélope Serrano-Ortiz
Biogeosciences, 21, 5117–5129, https://doi.org/10.5194/bg-21-5117-2024, https://doi.org/10.5194/bg-21-5117-2024, 2024
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Inland saline lakes are crucial in the global carbon cycle, but increased droughts may alter their carbon exchange capacity. We measured CO2 and CH4 fluxes in a Mediterranean saline lake using the eddy covariance method under dry and wet conditions. We found the lake acts as a carbon sink during wet periods but not during droughts. These results highlight the importance of saline lakes in carbon sequestration and their vulnerability to climate-change-induced droughts.
Luana Krebs, Susanne Burri, Iris Feigenwinter, Mana Gharun, Philip Meier, and Nina Buchmann
Biogeosciences, 21, 2005–2028, https://doi.org/10.5194/bg-21-2005-2024, https://doi.org/10.5194/bg-21-2005-2024, 2024
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This study explores year-round forest-floor greenhouse gas (GHG) fluxes in a Swiss spruce forest. Soil temperature and snow depth affected forest-floor respiration, while CH4 uptake was linked to snow cover. Negligible N2O fluxes were observed. In 2022, a warm year, CO2 emissions notably increased. The study suggests rising forest-floor GHG emissions due to climate change, impacting carbon sink behavior. Thus, for future forest management, continuous year-round GHG flux measurements are crucial.
Lukas Strebel, Heye Bogena, Harry Vereecken, Mie Andreasen, Sergio Aranda-Barranco, and Harrie-Jan Hendricks Franssen
Hydrol. Earth Syst. Sci., 28, 1001–1026, https://doi.org/10.5194/hess-28-1001-2024, https://doi.org/10.5194/hess-28-1001-2024, 2024
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We present results from using soil water content measurements from 13 European forest sites in a state-of-the-art land surface model. We use data assimilation to perform a combination of observed and modeled soil water content and show the improvements in the representation of soil water content. However, we also look at the impact on evapotranspiration and see no corresponding improvements.
Xinxu Zhao, Jia Chen, Julia Marshall, Michal Gałkowski, Stephan Hachinger, Florian Dietrich, Ankit Shekhar, Johannes Gensheimer, Adrian Wenzel, and Christoph Gerbig
Atmos. Chem. Phys., 23, 14325–14347, https://doi.org/10.5194/acp-23-14325-2023, https://doi.org/10.5194/acp-23-14325-2023, 2023
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We develop a modeling framework using the Weather Research and Forecasting model at a high spatial resolution (up to 400 m) to simulate atmospheric transport of greenhouse gases and interpret column observations. Output is validated against weather stations and column measurements in August 2018. The differential column method is applied, aided by air-mass transport tracing with the Stochastic Time-Inverted Lagrangian Transport (STILT) model, also for an exploratory measurement interpretation.
Qing Sun, Valentin H. Klaus, Raphaël Wittwer, Yujie Liu, Marcel G. A. van der Heijden, Anna K. Gilgen, and Nina Buchmann
Biogeosciences, 19, 1853–1869, https://doi.org/10.5194/bg-19-1853-2022, https://doi.org/10.5194/bg-19-1853-2022, 2022
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Drought is one of the biggest challenges for future food production globally. During a simulated drought, pea and barley mainly relied on water from shallow soil depths, independent of different cropping systems.
Andreas Riedl, Yafei Li, Jon Eugster, Nina Buchmann, and Werner Eugster
Hydrol. Earth Syst. Sci., 26, 91–116, https://doi.org/10.5194/hess-26-91-2022, https://doi.org/10.5194/hess-26-91-2022, 2022
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The aim of this study was to develop a high-accuracy micro-lysimeter system for the quantification of non-rainfall water inputs that overcomes existing drawbacks. The micro-lysimeter system had a high accuracy and allowed us to quantify and distinguish between different types of non-rainfall water inputs, like dew and fog. Non-rainfall water inputs occurred frequently in a Swiss Alpine grassland ecosystem. These water inputs can be an important water source for grasslands during dry periods.
Kyle B. Delwiche, Sara Helen Knox, Avni Malhotra, Etienne Fluet-Chouinard, Gavin McNicol, Sarah Feron, Zutao Ouyang, Dario Papale, Carlo Trotta, Eleonora Canfora, You-Wei Cheah, Danielle Christianson, Ma. Carmelita R. Alberto, Pavel Alekseychik, Mika Aurela, Dennis Baldocchi, Sheel Bansal, David P. Billesbach, Gil Bohrer, Rosvel Bracho, Nina Buchmann, David I. Campbell, Gerardo Celis, Jiquan Chen, Weinan Chen, Housen Chu, Higo J. Dalmagro, Sigrid Dengel, Ankur R. Desai, Matteo Detto, Han Dolman, Elke Eichelmann, Eugenie Euskirchen, Daniela Famulari, Kathrin Fuchs, Mathias Goeckede, Sébastien Gogo, Mangaliso J. Gondwe, Jordan P. Goodrich, Pia Gottschalk, Scott L. Graham, Martin Heimann, Manuel Helbig, Carole Helfter, Kyle S. Hemes, Takashi Hirano, David Hollinger, Lukas Hörtnagl, Hiroki Iwata, Adrien Jacotot, Gerald Jurasinski, Minseok Kang, Kuno Kasak, John King, Janina Klatt, Franziska Koebsch, Ken W. Krauss, Derrick Y. F. Lai, Annalea Lohila, Ivan Mammarella, Luca Belelli Marchesini, Giovanni Manca, Jaclyn Hatala Matthes, Trofim Maximov, Lutz Merbold, Bhaskar Mitra, Timothy H. Morin, Eiko Nemitz, Mats B. Nilsson, Shuli Niu, Walter C. Oechel, Patricia Y. Oikawa, Keisuke Ono, Matthias Peichl, Olli Peltola, Michele L. Reba, Andrew D. Richardson, William Riley, Benjamin R. K. Runkle, Youngryel Ryu, Torsten Sachs, Ayaka Sakabe, Camilo Rey Sanchez, Edward A. Schuur, Karina V. R. Schäfer, Oliver Sonnentag, Jed P. Sparks, Ellen Stuart-Haëntjens, Cove Sturtevant, Ryan C. Sullivan, Daphne J. Szutu, Jonathan E. Thom, Margaret S. Torn, Eeva-Stiina Tuittila, Jessica Turner, Masahito Ueyama, Alex C. Valach, Rodrigo Vargas, Andrej Varlagin, Alma Vazquez-Lule, Joseph G. Verfaillie, Timo Vesala, George L. Vourlitis, Eric J. Ward, Christian Wille, Georg Wohlfahrt, Guan Xhuan Wong, Zhen Zhang, Donatella Zona, Lisamarie Windham-Myers, Benjamin Poulter, and Robert B. Jackson
Earth Syst. Sci. Data, 13, 3607–3689, https://doi.org/10.5194/essd-13-3607-2021, https://doi.org/10.5194/essd-13-3607-2021, 2021
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Methane is an important greenhouse gas, yet we lack knowledge about its global emissions and drivers. We present FLUXNET-CH4, a new global collection of methane measurements and a critical resource for the research community. We use FLUXNET-CH4 data to quantify the seasonality of methane emissions from freshwater wetlands, finding that methane seasonality varies strongly with latitude. Our new database and analysis will improve wetland model accuracy and inform greenhouse gas budgets.
Anna B. Harper, Karina E. Williams, Patrick C. McGuire, Maria Carolina Duran Rojas, Debbie Hemming, Anne Verhoef, Chris Huntingford, Lucy Rowland, Toby Marthews, Cleiton Breder Eller, Camilla Mathison, Rodolfo L. B. Nobrega, Nicola Gedney, Pier Luigi Vidale, Fred Otu-Larbi, Divya Pandey, Sebastien Garrigues, Azin Wright, Darren Slevin, Martin G. De Kauwe, Eleanor Blyth, Jonas Ardö, Andrew Black, Damien Bonal, Nina Buchmann, Benoit Burban, Kathrin Fuchs, Agnès de Grandcourt, Ivan Mammarella, Lutz Merbold, Leonardo Montagnani, Yann Nouvellon, Natalia Restrepo-Coupe, and Georg Wohlfahrt
Geosci. Model Dev., 14, 3269–3294, https://doi.org/10.5194/gmd-14-3269-2021, https://doi.org/10.5194/gmd-14-3269-2021, 2021
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We evaluated 10 representations of soil moisture stress in the JULES land surface model against site observations of GPP and latent heat flux. Increasing the soil depth and plant access to deep soil moisture improved many aspects of the simulations, and we recommend these settings in future work using JULES. In addition, using soil matric potential presents the opportunity to include parameters specific to plant functional type to further improve modeled fluxes.
Yafei Li, Franziska Aemisegger, Andreas Riedl, Nina Buchmann, and Werner Eugster
Hydrol. Earth Syst. Sci., 25, 2617–2648, https://doi.org/10.5194/hess-25-2617-2021, https://doi.org/10.5194/hess-25-2617-2021, 2021
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During dry spells, dew and fog potentially play an increasingly important role in temperate grasslands. Research on the combined mechanisms of dew and fog inputs to ecosystems and distillation of water vapor from soil to plant surfaces is rare. Our results using stable water isotopes highlight the importance of dew and fog inputs to temperate grasslands during dry spells and reveal the complexity of the local water cycling in such conditions, including different pathways of dew and fog inputs.
Lutz Merbold, Charlotte Decock, Werner Eugster, Kathrin Fuchs, Benjamin Wolf, Nina Buchmann, and Lukas Hörtnagl
Biogeosciences, 18, 1481–1498, https://doi.org/10.5194/bg-18-1481-2021, https://doi.org/10.5194/bg-18-1481-2021, 2021
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Our study investigated the exchange of the three major greenhouse gases (GHGs) over a temperate grassland prior to and after restoration through tillage in central Switzerland. Our results show that irregular management events, such as tillage, have considerable effects on GHG emissions in the year of tillage while leading to enhanced carbon uptake and similar nitrogen losses via nitrous oxide in the years following tillage to those observed prior to tillage.
Chris R. Flechard, Andreas Ibrom, Ute M. Skiba, Wim de Vries, Marcel van Oijen, David R. Cameron, Nancy B. Dise, Janne F. J. Korhonen, Nina Buchmann, Arnaud Legout, David Simpson, Maria J. Sanz, Marc Aubinet, Denis Loustau, Leonardo Montagnani, Johan Neirynck, Ivan A. Janssens, Mari Pihlatie, Ralf Kiese, Jan Siemens, André-Jean Francez, Jürgen Augustin, Andrej Varlagin, Janusz Olejnik, Radosław Juszczak, Mika Aurela, Daniel Berveiller, Bogdan H. Chojnicki, Ulrich Dämmgen, Nicolas Delpierre, Vesna Djuricic, Julia Drewer, Eric Dufrêne, Werner Eugster, Yannick Fauvel, David Fowler, Arnoud Frumau, André Granier, Patrick Gross, Yannick Hamon, Carole Helfter, Arjan Hensen, László Horváth, Barbara Kitzler, Bart Kruijt, Werner L. Kutsch, Raquel Lobo-do-Vale, Annalea Lohila, Bernard Longdoz, Michal V. Marek, Giorgio Matteucci, Marta Mitosinkova, Virginie Moreaux, Albrecht Neftel, Jean-Marc Ourcival, Kim Pilegaard, Gabriel Pita, Francisco Sanz, Jan K. Schjoerring, Maria-Teresa Sebastià, Y. Sim Tang, Hilde Uggerud, Marek Urbaniak, Netty van Dijk, Timo Vesala, Sonja Vidic, Caroline Vincke, Tamás Weidinger, Sophie Zechmeister-Boltenstern, Klaus Butterbach-Bahl, Eiko Nemitz, and Mark A. Sutton
Biogeosciences, 17, 1583–1620, https://doi.org/10.5194/bg-17-1583-2020, https://doi.org/10.5194/bg-17-1583-2020, 2020
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Experimental evidence from a network of 40 monitoring sites in Europe suggests that atmospheric nitrogen deposition to forests and other semi-natural vegetation impacts the carbon sequestration rates in ecosystems, as well as the net greenhouse gas balance including other greenhouse gases such as nitrous oxide and methane. Excess nitrogen deposition in polluted areas also leads to other environmental impacts such as nitrogen leaching to groundwater and other pollutant gaseous emissions.
Chris R. Flechard, Marcel van Oijen, David R. Cameron, Wim de Vries, Andreas Ibrom, Nina Buchmann, Nancy B. Dise, Ivan A. Janssens, Johan Neirynck, Leonardo Montagnani, Andrej Varlagin, Denis Loustau, Arnaud Legout, Klaudia Ziemblińska, Marc Aubinet, Mika Aurela, Bogdan H. Chojnicki, Julia Drewer, Werner Eugster, André-Jean Francez, Radosław Juszczak, Barbara Kitzler, Werner L. Kutsch, Annalea Lohila, Bernard Longdoz, Giorgio Matteucci, Virginie Moreaux, Albrecht Neftel, Janusz Olejnik, Maria J. Sanz, Jan Siemens, Timo Vesala, Caroline Vincke, Eiko Nemitz, Sophie Zechmeister-Boltenstern, Klaus Butterbach-Bahl, Ute M. Skiba, and Mark A. Sutton
Biogeosciences, 17, 1621–1654, https://doi.org/10.5194/bg-17-1621-2020, https://doi.org/10.5194/bg-17-1621-2020, 2020
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Nitrogen deposition from the atmosphere to unfertilized terrestrial vegetation such as forests can increase carbon dioxide uptake and favour carbon sequestration by ecosystems. However the data from observational networks are difficult to interpret in terms of a carbon-to-nitrogen response, because there are a number of other confounding factors, such as climate, soil physical properties and fertility, and forest age. We propose a model-based method to untangle the different influences.
Kathrin Fuchs, Lukas Hörtnagl, Nina Buchmann, Werner Eugster, Val Snow, and Lutz Merbold
Biogeosciences, 15, 5519–5543, https://doi.org/10.5194/bg-15-5519-2018, https://doi.org/10.5194/bg-15-5519-2018, 2018
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Replacing fertiliser nitrogen with biologically fixed nitrogen (BFN) through legumes has been suggested as a strategy for nitrous oxide (N2O) mitigation from intensively managed grasslands. On our site the mitigation strategy reduced N2O emissions by 54 % and 39 % in 2015 and 2016, while annual yields were similar under mitigation management. We conclude that N2O emissions can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilisation.
Carmen Emmel, Annina Winkler, Lukas Hörtnagl, Andrew Revill, Christof Ammann, Petra D'Odorico, Nina Buchmann, and Werner Eugster
Biogeosciences, 15, 5377–5393, https://doi.org/10.5194/bg-15-5377-2018, https://doi.org/10.5194/bg-15-5377-2018, 2018
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It is of great interest to know whether croplands act as a net source or sink of atmospheric CO2 and if soil carbon (C) stocks are preserved over long timescales due to the role of C in soil fertility. For a cropland in Switzerland it was found that managing the field under the Swiss framework of the Proof of Ecological Performance (PEP) resulted in soil C losses of 18.0 %. Additional efforts are needed to bring Swiss management practices closer to the goal of preserving soil C in the long term.
Jannis von Buttlar, Jakob Zscheischler, Anja Rammig, Sebastian Sippel, Markus Reichstein, Alexander Knohl, Martin Jung, Olaf Menzer, M. Altaf Arain, Nina Buchmann, Alessandro Cescatti, Damiano Gianelle, Gerard Kiely, Beverly E. Law, Vincenzo Magliulo, Hank Margolis, Harry McCaughey, Lutz Merbold, Mirco Migliavacca, Leonardo Montagnani, Walter Oechel, Marian Pavelka, Matthias Peichl, Serge Rambal, Antonio Raschi, Russell L. Scott, Francesco P. Vaccari, Eva van Gorsel, Andrej Varlagin, Georg Wohlfahrt, and Miguel D. Mahecha
Biogeosciences, 15, 1293–1318, https://doi.org/10.5194/bg-15-1293-2018, https://doi.org/10.5194/bg-15-1293-2018, 2018
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Our work systematically quantifies extreme heat and drought event impacts on gross primary productivity (GPP) and ecosystem respiration globally across a wide range of ecosystems. We show that heat extremes typically increased mainly respiration whereas drought decreased both fluxes. Combined heat and drought extremes had opposing effects offsetting each other for respiration, but there were also strong reductions in GPP and hence the strongest reductions in the ecosystems carbon sink capacity.
Werner Eugster, Carmen Emmel, Sebastian Wolf, Nina Buchmann, Joseph P. McFadden, and Charles David Whiteman
Atmos. Chem. Phys., 17, 14887–14904, https://doi.org/10.5194/acp-17-14887-2017, https://doi.org/10.5194/acp-17-14887-2017, 2017
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The effects of penumbral shading of the solar eclipse of 20 March 2015 on near-surface meteorology across Switzerland (occultation 65.8–70.1 %) was investigated. Temperature effects at 184 weather stations are compared with temperature drops reported in the literature since 1834. A special focus is, however, put on wind direction effects observed at six flux sites (with 20 Hz data) and 165 meteorological stations (with 10 min resolution data). Results show the importance of local topography.
L. Wingate, J. Ogée, E. Cremonese, G. Filippa, T. Mizunuma, M. Migliavacca, C. Moisy, M. Wilkinson, C. Moureaux, G. Wohlfahrt, A. Hammerle, L. Hörtnagl, C. Gimeno, A. Porcar-Castell, M. Galvagno, T. Nakaji, J. Morison, O. Kolle, A. Knohl, W. Kutsch, P. Kolari, E. Nikinmaa, A. Ibrom, B. Gielen, W. Eugster, M. Balzarolo, D. Papale, K. Klumpp, B. Köstner, T. Grünwald, R. Joffre, J.-M. Ourcival, M. Hellstrom, A. Lindroth, C. George, B. Longdoz, B. Genty, J. Levula, B. Heinesch, M. Sprintsin, D. Yakir, T. Manise, D. Guyon, H. Ahrends, A. Plaza-Aguilar, J. H. Guan, and J. Grace
Biogeosciences, 12, 5995–6015, https://doi.org/10.5194/bg-12-5995-2015, https://doi.org/10.5194/bg-12-5995-2015, 2015
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The timing of plant development stages and their response to climate and management were investigated using a network of digital cameras installed across different European ecosystems. Using the relative red, green and blue content of images we showed that the green signal could be used to estimate the length of the growing season in broadleaf forests. We also developed a model that predicted the seasonal variations of camera RGB signals and how they relate to leaf pigment content and area well.
G. Wohlfahrt, C. Amelynck, C. Ammann, A. Arneth, I. Bamberger, A. H. Goldstein, L. Gu, A. Guenther, A. Hansel, B. Heinesch, T. Holst, L. Hörtnagl, T. Karl, Q. Laffineur, A. Neftel, K. McKinney, J. W. Munger, S. G. Pallardy, G. W. Schade, R. Seco, and N. Schoon
Atmos. Chem. Phys., 15, 7413–7427, https://doi.org/10.5194/acp-15-7413-2015, https://doi.org/10.5194/acp-15-7413-2015, 2015
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Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of plants as the major source and the reaction with OH as the major sink, global methanol budgets diverge considerably in terms of source/sink estimates. Here we present micrometeorological methanol flux data from eight sites in order to provide a first cross-site synthesis of the terrestrial methanol exchange.
L. Hörtnagl and G. Wohlfahrt
Biogeosciences, 11, 7219–7236, https://doi.org/10.5194/bg-11-7219-2014, https://doi.org/10.5194/bg-11-7219-2014, 2014
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The methane (CH4) and nitrous oxide (N2O) exchange of a temperate mountain grassland near Neustift, Austria, was measured during 2010–2012 over a time period of 22 months using the eddy covariance method. The meadow acted as a sink for both compounds during certain time periods, but was a clear source of CH4 and N2O on an annual timescale. Both gases contributed to an increase of the global warming potential (GWP), effectively reducing the sink strength in terms of CO2 equivalents.
L. Hörtnagl, I. Bamberger, M. Graus, T. M. Ruuskanen, R. Schnitzhofer, M. Walser, A. Unterberger, A. Hansel, and G. Wohlfahrt
Atmos. Chem. Phys., 14, 5369–5391, https://doi.org/10.5194/acp-14-5369-2014, https://doi.org/10.5194/acp-14-5369-2014, 2014
I. Bamberger, L. Hörtnagl, M. Walser, A. Hansel, and G. Wohlfahrt
Biogeosciences, 11, 2429–2442, https://doi.org/10.5194/bg-11-2429-2014, https://doi.org/10.5194/bg-11-2429-2014, 2014
M. Verma, M. A. Friedl, A. D. Richardson, G. Kiely, A. Cescatti, B. E. Law, G. Wohlfahrt, B. Gielen, O. Roupsard, E. J. Moors, P. Toscano, F. P. Vaccari, D. Gianelle, G. Bohrer, A. Varlagin, N. Buchmann, E. van Gorsel, L. Montagnani, and P. Propastin
Biogeosciences, 11, 2185–2200, https://doi.org/10.5194/bg-11-2185-2014, https://doi.org/10.5194/bg-11-2185-2014, 2014
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Aggregation of ice-nucleating macromolecules from Betula pendula pollen determines ice nucleation efficiency
Future Forests: estimating biogenic emissions from net-zero aligned afforestation pathways in the UK
Evaluating adsorption isotherm models for determining the partitioning of ammonium between soil and soil pore water in environmental soil samples
Similar freezing spectra of particles in plant canopies and in the air at a high-altitude site
Anticorrelation of net uptake of atmospheric CO2 by the world ocean and terrestrial biosphere in current carbon cycle models
Impact of meteorological conditions on the biogenic volatile organic compound (BVOC) emission rate from eastern Mediterranean vegetation under drought
Monitoring cropland daily carbon dioxide exchange at field scales with Sentinel-2 satellite imagery
The influence of plant water stress on vegetation–atmosphere exchanges: implications for ozone modelling
High interspecific variability in ice nucleation activity suggests pollen ice nucleators are incidental
Using automated machine learning for the upscaling of gross primary productivity
Interpretability of negative latent heat fluxes from eddy covariance measurements in dry conditions
Forest-floor respiration, N2O fluxes, and CH4 fluxes in a subalpine spruce forest: drivers and annual budgets
Enhanced net CO2 exchange of a semideciduous forest in the southern Amazon due to diffuse radiation from biomass burning
Observational relationships between ammonia, carbon dioxide and water vapor under a wide range of meteorological and turbulent conditions: RITA-2021 campaign
Environmental controls of winter soil carbon dioxide fluxes in boreal and tundra environments
Origin of secondary fatty alcohols in atmospheric aerosols in a cool–temperate forest based on their mass size distributions
Sap flow and leaf gas exchange response to a drought and heatwave in urban green spaces in a Nordic city
Changes in biogenic volatile organic compound emissions in response to the El Niño–Southern Oscillation
Rethinking the deployment of static chambers for CO2 flux measurement in dry desert soils
Lichen species across Alaska produce highly active and stable ice nucleators
A differentiable, physics-informed ecosystem modeling and learning framework for large-scale inverse problems: demonstration with photosynthesis simulations
Snow–vegetation–atmosphere interactions in alpine tundra
Synergy between TROPOMI sun-induced chlorophyll fluorescence and MODIS spectral reflectance for understanding the dynamics of gross primary productivity at Integrated Carbon Observatory System (ICOS) ecosystem flux sites
Atmospheric deposition of reactive nitrogen to a deciduous forest in the southern Appalachian Mountains
Tropical cyclones facilitate recovery of forest leaf area from dry spells in East Asia
Minor contributions of daytime monoterpenes are major contributors to atmospheric reactivity
Using atmospheric observations to quantify annual biogenic carbon dioxide fluxes on the Alaska North Slope
Forest–atmosphere exchange of reactive nitrogen in a remote region – Part II: Modeling annual budgets
Growth and actual leaf temperature modulate CO2 responsiveness of monoterpene emissions from holm oak in opposite ways
Multi-year observations reveal a larger than expected autumn respiration signal across northeast Eurasia
Reviews and syntheses: VOC emissions from soil cover in boreal and temperate natural ecosystems of the Northern Hemisphere
Internal tree cycling and atmospheric archiving of mercury: examination with concentration and stable isotope analyses
Contrasting drought legacy effects on gross primary productivity in a mixed versus pure beech forest
CO2 and CH4 exchanges between moist moss tundra and atmosphere on Kapp Linné, Svalbard
Recent extreme drought events in the Amazon rainforest: assessment of different precipitation and evapotranspiration datasets and drought indicators
Variability and uncertainty in flux-site-scale net ecosystem exchange simulations based on machine learning and remote sensing: a systematic evaluation
Update of a biogeochemical model with process-based algorithms to predict ammonia volatilization from fertilized cultivated uplands and rice paddy fields
Massive warming-induced carbon loss from subalpine grassland soils in an altitudinal transplantation experiment
Climatic variation drives loss and restructuring of carbon and nitrogen in boreal forest wildfire
Gaps in network infrastructure limit our understanding of biogenic methane emissions for the United States
Nicholas Cowan, Toby Roberts, Mark Hanlon, Aurelia Bezanger, Galina Toteva, Alex Tweedie, Karen Yeung, Ajinkya Deshpande, Peter Levy, Ute Skiba, Eiko Nemitz, and Julia Drewer
Biogeosciences, 22, 3449–3461, https://doi.org/10.5194/bg-22-3449-2025, https://doi.org/10.5194/bg-22-3449-2025, 2025
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We measured soil hydrogen (H2) fluxes from two field sites, a managed grassland and a planted deciduous woodland, with flux measurements of H2 covering full seasonal cycles. We estimate annual H2 uptake of −3.1 ± 0.1 and −12.0 ± 0.4 kg H2 ha−1 yr−1 for the grassland and woodland sites, respectively. Soil moisture was found to be the primary driver of H2 uptake, with the silt/clay content of the soils providing a physical barrier which limited H2 uptake.
Piaopiao Ke, Anna Lintunen, Pasi Kolari, Annalea Lohila, Santeri Tuovinen, Janne Lampilahti, Roseline Thakur, Maija Peltola, Otso Peräkylä, Tuomo Nieminen, Ekaterina Ezhova, Mari Pihlatie, Asta Laasonen, Markku Koskinen, Helena Rautakoski, Laura Heimsch, Tom Kokkonen, Aki Vähä, Ivan Mammarella, Steffen Noe, Jaana Bäck, Veli-Matti Kerminen, and Markku Kulmala
Biogeosciences, 22, 3235–3251, https://doi.org/10.5194/bg-22-3235-2025, https://doi.org/10.5194/bg-22-3235-2025, 2025
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Our research explores diverse ecosystems’ roles in climate cooling via the concept of CarbonSink+ potential. We measured CO2 uptake and local aerosol production in forests, farms, peatlands, urban gardens, and coastal areas across Finland and Estonia. The long-term data reveal that, while forests are vital with regard to CarbonSink+ potential, farms and urban gardens also play significant roles. These insights can help optimize management policy of natural resources to mitigate global warming.
Laura Nadolski, Tarek S. El-Madany, Jacob Nelson, Arnaud Carrara, Gerardo Moreno, Richard Nair, Yunpeng Luo, Anke Hildebrandt, Victor Rolo, Markus Reichstein, and Sung-Ching Lee
Biogeosciences, 22, 2935–2958, https://doi.org/10.5194/bg-22-2935-2025, https://doi.org/10.5194/bg-22-2935-2025, 2025
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Semi-arid ecosystems are crucial for Earth's carbon balance and are sensitive to changes in nitrogen (N) and phosphorus (P) levels. Their carbon dynamics are complex and not fully understood. We studied how long-term nutrient changes affect carbon exchange. In summer, the addition of N+P changed plant composition and productivity. In transitional seasons, carbon exchange was less weather-dependent with N. The addition of N and N+P increases carbon-exchange variability, driven by grass greenness.
Rosemary J. Eufemio, Galit Renzer, Mariah Rojas, Jolanta Miadlikowska, Todd L. Sformo, François Lutzoni, Boris A. Vinatzer, and Konrad Meister
Biogeosciences, 22, 2087–2096, https://doi.org/10.5194/bg-22-2087-2025, https://doi.org/10.5194/bg-22-2087-2025, 2025
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Biological ice nucleation plays key roles in organism survival and in shaping Earth’s atmospheric patterns. Our pan-American screening of Peltigera lichens reveals that the lichen thalli produce highly active ice nucleators (INs) resistant to freeze–thaw cycles. Notably, a pure fungal culture from Peltigera britannica released the most potent INs reported to date. Given the global abundance of these lichens, the INs may be important contributors to atmospheric processes.
Mubaraq Olarewaju Abdulwahab, Christophe Flechard, Yannick Fauvel, Christoph Häni, Adrien Jacotot, Anne-Isabelle Graux, Nadège Edouard, Pauline Buysse, Valérie Viaud, and Albrecht Neftel
EGUsphere, https://doi.org/10.5194/egusphere-2025-1605, https://doi.org/10.5194/egusphere-2025-1605, 2025
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Pastures are an important source of ammonia, a major atmospheric pollutant with manifold environmental impacts. Ammonia is emitted from the decomposition of cattle urine in soils during grazing. We used micrometeorological methods to measure emissions over four grazing seasons. The results show the influence of weather and grassland management on emission processes. Emission factors, used to compile regional inventories, are hugely variable and still very uncertain despite decades of research.
Excellent O. Eboigbe, Nimelan Veerasamy, Abiodun M. Odukoya, Nnamdi C. Anene, Jeroen E. Sonke, Sayuri Sakisaka Méndez, and David S. McLagan
EGUsphere, https://doi.org/10.5194/egusphere-2025-1402, https://doi.org/10.5194/egusphere-2025-1402, 2025
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Air, soil, and three common staple crops were assess at an ASGM processing site and Hg contamination observed at a farm ≈500 m from the processing site. Of the crop tissues examined, foliage had the highest concentrations. Mercury stable isotopes indicate uptake of mercury from the air to the foliage as is the dominant uptake pathway. Using typical dietary data for Nigerians, Hg intake from these crops were below reference dose levels and generally safe for consumption.
Inês Vieira, Félicien Meunier, Maria Carolina Duran Rojas, Stephen Sitch, Flossie Brown, Giacomo Gerosa, Silvano Fares, Pascal Boeckx, Marijn Bauters, and Hans Verbeeck
EGUsphere, https://doi.org/10.5194/egusphere-2025-1375, https://doi.org/10.5194/egusphere-2025-1375, 2025
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We used a computer model to study how ozone pollution reduces plant growth in six European forests, from Finland to Italy. Combining field data and simulations, we found that ozone can lower carbon uptake by up to 6 % each year, especially in Mediterranean areas. Our study shows that local climate and forest type influence ozone damage and highlights the need to include ozone effects in forest and climate models.
Archana Dayalu, Marikate Mountain, Bharat Rastogi, John B. Miller, and Luciana Gatti
Biogeosciences, 22, 1509–1528, https://doi.org/10.5194/bg-22-1509-2025, https://doi.org/10.5194/bg-22-1509-2025, 2025
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The Amazon is facing unprecedented disturbance. Determining trends in Amazonia's carbon balance and its sensitivity to disturbance requires reliable vegetation models that adequately capture how its ecosystems exchange carbon with the atmosphere. Using ground- and satellite-based ecosystem products, we present an improved model of land–atmosphere vegetation carbon exchange across the Amazon. Our model agrees with independent aircraft observations from different locations.
José Ángel Callejas-Rodelas, Alexander Knohl, Ivan Mammarella, Timo Vesala, Olli Peltola, and Christian Markwitz
EGUsphere, https://doi.org/10.5194/egusphere-2025-810, https://doi.org/10.5194/egusphere-2025-810, 2025
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The spatial variability of CO2 and water vapour exchanges with the atmosphere was quantified above an agroforestry system, and further compared to a monocropping system, using a total of four eddy covariance stations. The variability of fluxes within the agroforestry was found to be as large as the variability between agroforestry and monocropping, induced by the heterogeneity of the site, which highlights the need for replicated measurements above such ecosystems.
Andrew S. Kowalski
Biogeosciences, 22, 785–789, https://doi.org/10.5194/bg-22-785-2025, https://doi.org/10.5194/bg-22-785-2025, 2025
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The laws of physics show that leaf oxygen is not photosynthetically enriched but extremely dilute due to the overwhelming effects of humidification. This challenges the prevailing diffusion-only paradigm regarding leaf gas exchanges because non-diffusive transport is required. Such transport also explains why fluxes of carbon dioxide and water vapour become decoupled at very high temperatures, as has been observed but not explained by plant physiologists.
Florian Wieland, Nadine Bothen, Ralph Schwidetzky, Teresa M. Seifried, Paul Bieber, Ulrich Pöschl, Konrad Meister, Mischa Bonn, Janine Fröhlich-Nowoisky, and Hinrich Grothe
Biogeosciences, 22, 103–115, https://doi.org/10.5194/bg-22-103-2025, https://doi.org/10.5194/bg-22-103-2025, 2025
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Betula pendula is a widespread birch tree species containing ice nucleation agents that can trigger the freezing of cloud droplets and thereby alter the evolution of clouds. Our study identifies three distinct ice-nucleating macromolecule (INM) aggregates of varying size that can nucleate ice at temperatures up to –5.4°C. Our findings suggest that these vegetation-derived particles may influence atmospheric processes, weather, and climate more strongly than previously thought.
Hazel Mooney, Stephen Arnold, Benjamin Silver, Piers Forster, and Catherine Scott
EGUsphere, https://doi.org/10.5194/egusphere-2024-3895, https://doi.org/10.5194/egusphere-2024-3895, 2025
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We simulate the potential changes in natural emissions of volatile gases from the land surface in the UK following afforestation from present-day woodland cover of 13 % to 19 % by 2050. We estimate present-day annual UK emissions of isoprene at 40 kt yr-1 and total monoterpenes at 46 kt yr-1, but emissions from afforested experiments show between a 4 % decrease and 131 % increase in emissions, explained by the variation in emissions activity between and within needleleaf and broadleaf trees.
Matthew G. Davis, Kevin Yan, and Jennifer G. Murphy
Biogeosciences, 21, 5381–5392, https://doi.org/10.5194/bg-21-5381-2024, https://doi.org/10.5194/bg-21-5381-2024, 2024
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Ammonia applied as fertilizer can volatilize into the atmosphere. This can threaten vulnerable ecosystems and human health. We investigated the partitioning of ammonia between an immobile adsorbed phase and mobile aqueous phase using several adsorption models. Using the Temkin model we determined that previous approaches to this issue may overestimate the quantity available for exchange by a factor of 5–20, suggesting that ammonia emissions from soil may be overestimated.
Annika Einbock and Franz Conen
Biogeosciences, 21, 5219–5231, https://doi.org/10.5194/bg-21-5219-2024, https://doi.org/10.5194/bg-21-5219-2024, 2024
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A small fraction of particles found at great heights in the atmosphere can freeze cloud droplets at temperatures of ≥ −10 °C and thus influence cloud properties. We provide a novel type of evidence that plant canopies are a major source of such biological ice-nucleating particles in the air above the Alps, potentially affecting mixed-phase cloud development.
Stephen E. Schwartz
Biogeosciences, 21, 5045–5057, https://doi.org/10.5194/bg-21-5045-2024, https://doi.org/10.5194/bg-21-5045-2024, 2024
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Anticorrelation in uptake of atmospheric CO2 following pulse emission or abrupt cessation of emissions is examined in two key model intercomparison studies. In both studies net transfer coefficients from the atmosphere to the world ocean and the terrestrial biosphere are anticorrelated across models, reducing inter-model diversity in decrease of atmospheric CO2 following the perturbation, increasing uncertainties of global warming potentials and consequences of prospective emission reductions.
Qian Li, Gil Lerner, Einat Bar, Efraim Lewinsohn, and Eran Tas
Biogeosciences, 21, 4133–4147, https://doi.org/10.5194/bg-21-4133-2024, https://doi.org/10.5194/bg-21-4133-2024, 2024
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Our research indicates that instantaneous changes in meteorological parameters better reflect drought-induced changes in the emission rates of biogenic volatile organic compounds (BVOCs) from natural vegetation than their absolute values. However, following a small amount of irrigation, this trend became more moderate or reversed, accompanied by a dramatic increase in BVOC emission rates. These findings advance our understanding of BVOC emissions under climate change.
Pia Gottschalk, Aram Kalhori, Zhan Li, Christian Wille, and Torsten Sachs
Biogeosciences, 21, 3593–3616, https://doi.org/10.5194/bg-21-3593-2024, https://doi.org/10.5194/bg-21-3593-2024, 2024
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To improve the accuracy of spatial carbon exchange estimates, we evaluated simple linear models for net ecosystem exchange (NEE) and gross primary productivity (GPP) and how they can be used to upscale the CO2 exchange of agricultural fields. The models are solely driven by Sentinel-2-derived vegetation indices (VIs). Evaluations show that different VIs have variable power to estimate NEE and GPP of crops in different years. The overall performance is as good as results from complex crop models.
Tamara Emmerichs, Yen-Sen Lu, and Domenico Taraborrelli
Biogeosciences, 21, 3251–3269, https://doi.org/10.5194/bg-21-3251-2024, https://doi.org/10.5194/bg-21-3251-2024, 2024
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We assess the representation of the plant response to surface water in a global atmospheric chemistry model. This sensitivity is crucial for the return of precipitation back into the atmosphere and thus significantly impacts the representation of weather as well as air quality. The newly implemented response function reduces this process and has a better comparison with satellite observations. This yields a higher intensity of unusual warm periods and higher production of air pollutants.
Nina L. H. Kinney, Charles A. Hepburn, Matthew I. Gibson, Daniel Ballesteros, and Thomas F. Whale
Biogeosciences, 21, 3201–3214, https://doi.org/10.5194/bg-21-3201-2024, https://doi.org/10.5194/bg-21-3201-2024, 2024
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Molecules released from plant pollen induce the formation of ice from supercooled water at temperatures warm enough to suggest an underlying function for this activity. In this study we show that ice nucleators are ubiquitous in pollen. We suggest the molecules responsible fulfil some unrelated biological function and nucleate ice incidentally. The ubiquity of ice-nucleating molecules in pollen and particularly active examples reveal a greater potential for pollen to impact weather and climate.
Max Gaber, Yanghui Kang, Guy Schurgers, and Trevor Keenan
Biogeosciences, 21, 2447–2472, https://doi.org/10.5194/bg-21-2447-2024, https://doi.org/10.5194/bg-21-2447-2024, 2024
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Gross primary productivity (GPP) describes the photosynthetic carbon assimilation, which plays a vital role in the carbon cycle. We can measure GPP locally, but producing larger and continuous estimates is challenging. Here, we present an approach to extrapolate GPP to a global scale using satellite imagery and automated machine learning. We benchmark different models and predictor variables and achieve an estimate that can capture 75 % of the variation in GPP.
Sinikka J. Paulus, Rene Orth, Sung-Ching Lee, Anke Hildebrandt, Martin Jung, Jacob A. Nelson, Tarek Sebastian El-Madany, Arnaud Carrara, Gerardo Moreno, Matthias Mauder, Jannis Groh, Alexander Graf, Markus Reichstein, and Mirco Migliavacca
Biogeosciences, 21, 2051–2085, https://doi.org/10.5194/bg-21-2051-2024, https://doi.org/10.5194/bg-21-2051-2024, 2024
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Porous materials are known to reversibly trap water from the air, even at low humidity. However, this behavior is poorly understood for soils. In this analysis, we test whether eddy covariance is able to measure the so-called adsorption of atmospheric water vapor by soils. We find that this flux occurs frequently during dry nights in a Mediterranean ecosystem, while EC detects downwardly directed vapor fluxes. These results can help to map moisture uptake globally.
Luana Krebs, Susanne Burri, Iris Feigenwinter, Mana Gharun, Philip Meier, and Nina Buchmann
Biogeosciences, 21, 2005–2028, https://doi.org/10.5194/bg-21-2005-2024, https://doi.org/10.5194/bg-21-2005-2024, 2024
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This study explores year-round forest-floor greenhouse gas (GHG) fluxes in a Swiss spruce forest. Soil temperature and snow depth affected forest-floor respiration, while CH4 uptake was linked to snow cover. Negligible N2O fluxes were observed. In 2022, a warm year, CO2 emissions notably increased. The study suggests rising forest-floor GHG emissions due to climate change, impacting carbon sink behavior. Thus, for future forest management, continuous year-round GHG flux measurements are crucial.
Simone Rodrigues, Glauber Cirino, Demerval Moreira, Andrea Pozzer, Rafael Palácios, Sung-Ching Lee, Breno Imbiriba, José Nogueira, Maria Isabel Vitorino, and George Vourlitis
Biogeosciences, 21, 843–868, https://doi.org/10.5194/bg-21-843-2024, https://doi.org/10.5194/bg-21-843-2024, 2024
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The radiative effects of atmospheric particles are still unknown for a wide variety of species and types of vegetation present in Amazonian biomes. We examined the effects of aerosols on solar radiation and their impacts on photosynthesis in an area of semideciduous forest in the southern Amazon Basin. Under highly smoky-sky conditions, our results show substantial photosynthetic interruption (20–70 %), attributed specifically to the decrease in solar radiation and leaf canopy temperature.
Ruben B. Schulte, Jordi Vilà-Guerau de Arellano, Susanna Rutledge-Jonker, Shelley van der Graaf, Jun Zhang, and Margreet C. van Zanten
Biogeosciences, 21, 557–574, https://doi.org/10.5194/bg-21-557-2024, https://doi.org/10.5194/bg-21-557-2024, 2024
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We analyzed measurements with the aim of finding relations between the surface atmosphere exchange of NH3 and the CO2 uptake and transpiration by vegetation. We found a high correlation of daytime NH3 emissions with both latent heat flux and photosynthetically active radiation. Very few simultaneous measurements of NH3, CO2 fluxes and meteorological variables exist at sub-diurnal timescales. This study paves the way to finding more robust relations between the NH3 exchange flux and CO2 uptake.
Alex Mavrovic, Oliver Sonnentag, Juha Lemmetyinen, Carolina Voigt, Nick Rutter, Paul Mann, Jean-Daniel Sylvain, and Alexandre Roy
Biogeosciences, 20, 5087–5108, https://doi.org/10.5194/bg-20-5087-2023, https://doi.org/10.5194/bg-20-5087-2023, 2023
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We present an analysis of soil CO2 emissions in boreal and tundra regions during the non-growing season. We show that when the soil is completely frozen, soil temperature is the main control on CO2 emissions. When the soil is around the freezing point, with a mix of liquid water and ice, the liquid water content is the main control on CO2 emissions. This study highlights that the vegetation–snow–soil interactions must be considered to understand soil CO2 emissions during the non-growing season.
Yuhao Cui, Eri Tachibana, Kimitaka Kawamura, and Yuzo Miyazaki
Biogeosciences, 20, 4969–4980, https://doi.org/10.5194/bg-20-4969-2023, https://doi.org/10.5194/bg-20-4969-2023, 2023
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Fatty alcohols (FAs) are major components of surface lipids in plant leaves and serve as surface-active aerosols. Our study on the aerosol size distributions in a forest suggests that secondary FAs (SFAs) originated from plant waxes and that leaf senescence status is likely an important factor controlling the size distribution of SFAs. This study provides new insights into the sources of primary biological aerosol particles (PBAPs) and their effects on the aerosol ice nucleation activity.
Joyson Ahongshangbam, Liisa Kulmala, Jesse Soininen, Yasmin Frühauf, Esko Karvinen, Yann Salmon, Anna Lintunen, Anni Karvonen, and Leena Järvi
Biogeosciences, 20, 4455–4475, https://doi.org/10.5194/bg-20-4455-2023, https://doi.org/10.5194/bg-20-4455-2023, 2023
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Urban vegetation is important for removing urban CO2 emissions and cooling. We studied the response of urban trees' functions (photosynthesis and transpiration) to a heatwave and drought at four urban green areas in the city of Helsinki. We found that tree water use was increased during heatwave and drought periods, but there was no change in the photosynthesis rates. The heat and drought conditions were severe at the local scale but were not excessive enough to restrict urban trees' functions.
Ryan Vella, Andrea Pozzer, Matthew Forrest, Jos Lelieveld, Thomas Hickler, and Holger Tost
Biogeosciences, 20, 4391–4412, https://doi.org/10.5194/bg-20-4391-2023, https://doi.org/10.5194/bg-20-4391-2023, 2023
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We investigated the effect of the El Niño–Southern Oscillation (ENSO) on biogenic volatile organic compound (BVOC) emissions from plants. ENSO events can cause a significant increase in these emissions, which have a long-term impact on the Earth's atmosphere. Persistent ENSO conditions can cause long-term changes in vegetation, resulting in even higher BVOC emissions. We link ENSO-induced emission anomalies with driving atmospheric and vegetational variables.
Nadav Bekin and Nurit Agam
Biogeosciences, 20, 3791–3802, https://doi.org/10.5194/bg-20-3791-2023, https://doi.org/10.5194/bg-20-3791-2023, 2023
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The mechanisms of soil CO2 flux in dry desert soils are not fully understood. Yet studies conducted in desert ecosystems rarely discuss potential errors related to using the commonly used flux chambers in dry and bare soils. In our study, the conventional deployment practice of the chambers underestimated the instantaneous CO2 flux by up to 50 % and the total daily CO2 uptake by 35 %. This suggests that desert soils are a larger carbon sink than previously reported.
Rosemary J. Eufemio, Ingrid de Almeida Ribeiro, Todd L. Sformo, Gary A. Laursen, Valeria Molinero, Janine Fröhlich-Nowoisky, Mischa Bonn, and Konrad Meister
Biogeosciences, 20, 2805–2812, https://doi.org/10.5194/bg-20-2805-2023, https://doi.org/10.5194/bg-20-2805-2023, 2023
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Lichens, the dominant vegetation in the Arctic, contain ice nucleators (INs) that enable freezing close to 0°C. Yet the abundance, diversity, and function of lichen INs is unknown. Our screening of lichens across Alaska reveal that most species have potent INs. We find that lichens contain two IN populations which retain activity under environmentally relevant conditions. The ubiquity and stability of lichen INs suggest that they may have considerable impacts on local atmospheric patterns.
Doaa Aboelyazeed, Chonggang Xu, Forrest M. Hoffman, Jiangtao Liu, Alex W. Jones, Chris Rackauckas, Kathryn Lawson, and Chaopeng Shen
Biogeosciences, 20, 2671–2692, https://doi.org/10.5194/bg-20-2671-2023, https://doi.org/10.5194/bg-20-2671-2023, 2023
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Photosynthesis is critical for life and has been affected by the changing climate. Many parameters come into play while modeling, but traditional calibration approaches face many issues. Our framework trains coupled neural networks to provide parameters to a photosynthesis model. Using big data, we independently found parameter values that were correlated with those in the literature while giving higher correlation and reduced biases in photosynthesis rates.
Norbert Pirk, Kristoffer Aalstad, Yeliz A. Yilmaz, Astrid Vatne, Andrea L. Popp, Peter Horvath, Anders Bryn, Ane Victoria Vollsnes, Sebastian Westermann, Terje Koren Berntsen, Frode Stordal, and Lena Merete Tallaksen
Biogeosciences, 20, 2031–2047, https://doi.org/10.5194/bg-20-2031-2023, https://doi.org/10.5194/bg-20-2031-2023, 2023
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We measured the land–atmosphere exchange of CO2 and water vapor in alpine Norway over 3 years. The extremely snow-rich conditions in 2020 reduced the total annual evapotranspiration to 50 % and reduced the growing-season carbon assimilation to turn the ecosystem from a moderate annual carbon sink to an even stronger source. Our analysis suggests that snow cover anomalies are driving the most consequential short-term responses in this ecosystem’s functioning.
Hamadou Balde, Gabriel Hmimina, Yves Goulas, Gwendal Latouche, and Kamel Soudani
Biogeosciences, 20, 1473–1490, https://doi.org/10.5194/bg-20-1473-2023, https://doi.org/10.5194/bg-20-1473-2023, 2023
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This study focuses on the relationship between sun-induced chlorophyll fluorescence (SIF) and ecosystem gross primary productivity (GPP) across the ICOS European flux tower network. It shows that SIF, coupled with reflectance observations, explains over 80 % of the GPP variability across diverse ecosystems but fails to bring new information compared to reflectance alone at coarse spatial scales (~5 km). These findings have applications in agriculture and ecophysiological studies.
John T. Walker, Xi Chen, Zhiyong Wu, Donna Schwede, Ryan Daly, Aleksandra Djurkovic, A. Christopher Oishi, Eric Edgerton, Jesse Bash, Jennifer Knoepp, Melissa Puchalski, John Iiames, and Chelcy F. Miniat
Biogeosciences, 20, 971–995, https://doi.org/10.5194/bg-20-971-2023, https://doi.org/10.5194/bg-20-971-2023, 2023
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Better estimates of atmospheric nitrogen (N) deposition are needed to accurately assess ecosystem risk and impacts from deposition of nutrients and acidity. Using measurements and modeling, we estimate total N deposition of 6.7 kg N ha−1 yr−1 at a forest site in the southern Appalachian Mountains, a region sensitive to atmospheric deposition. Reductions in deposition of reduced forms of N (ammonia and ammonium) will be needed to meet the lowest estimates of N critical loads for the region.
Yi-Ying Chen and Sebastiaan Luyssaert
Biogeosciences, 20, 349–363, https://doi.org/10.5194/bg-20-349-2023, https://doi.org/10.5194/bg-20-349-2023, 2023
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Tropical cyclones are typically assumed to be associated with ecosystem damage. This study challenges this assumption and suggests that instead of reducing leaf area, cyclones in East Asia may increase leaf area by alleviating water stress.
Deborah F. McGlynn, Graham Frazier, Laura E. R. Barry, Manuel T. Lerdau, Sally E. Pusede, and Gabriel Isaacman-VanWertz
Biogeosciences, 20, 45–55, https://doi.org/10.5194/bg-20-45-2023, https://doi.org/10.5194/bg-20-45-2023, 2023
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Using a custom-made gas chromatography flame ionization detector, 2 years of speciated hourly biogenic volatile organic compound data were collected in a forest in central Virginia. We identify diurnal and seasonal variability in the data, which is shown to impact atmospheric oxidant budgets. A comparison with emission models identified discrepancies with implications for model outcomes. We suggest increased monitoring of speciated biogenic volatile organic compounds to improve modeled results.
Luke D. Schiferl, Jennifer D. Watts, Erik J. L. Larson, Kyle A. Arndt, Sébastien C. Biraud, Eugénie S. Euskirchen, Jordan P. Goodrich, John M. Henderson, Aram Kalhori, Kathryn McKain, Marikate E. Mountain, J. William Munger, Walter C. Oechel, Colm Sweeney, Yonghong Yi, Donatella Zona, and Róisín Commane
Biogeosciences, 19, 5953–5972, https://doi.org/10.5194/bg-19-5953-2022, https://doi.org/10.5194/bg-19-5953-2022, 2022
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As the Arctic rapidly warms, vast stores of thawing permafrost could release carbon dioxide (CO2) into the atmosphere. We combined observations of atmospheric CO2 concentrations from aircraft and a tower with observed CO2 fluxes from tundra ecosystems and found that the Alaskan North Slope in not a consistent source nor sink of CO2. Our study shows the importance of using both site-level and atmospheric measurements to constrain regional net CO2 fluxes and improve biogenic processes in models.
Pascal Wintjen, Frederik Schrader, Martijn Schaap, Burkhard Beudert, Richard Kranenburg, and Christian Brümmer
Biogeosciences, 19, 5287–5311, https://doi.org/10.5194/bg-19-5287-2022, https://doi.org/10.5194/bg-19-5287-2022, 2022
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For the first time, we compared four methods for estimating the annual dry deposition of total reactive nitrogen into a low-polluted forest ecosystem. In our analysis, we used 2.5 years of flux measurements, an in situ modeling approach, a large-scale chemical transport model (CTM), and canopy budget models. Annual nitrogen dry deposition budgets ranged between 4.3 and 6.7 kg N ha−1 a−1, depending on the applied method.
Michael Staudt, Juliane Daussy, Joseph Ingabire, and Nafissa Dehimeche
Biogeosciences, 19, 4945–4963, https://doi.org/10.5194/bg-19-4945-2022, https://doi.org/10.5194/bg-19-4945-2022, 2022
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We studied the short- and long-term effects of CO2 as a function of temperature on monoterpene emissions from holm oak. Similarly to isoprene, emissions decreased non-linearly with increasing CO2, with no differences among compounds and chemotypes. The CO2 response was modulated by actual leaf and growth temperature but not by growth CO2. Estimates of annual monoterpene release under double CO2 suggest that CO2 inhibition does not offset the increase in emissions due to expected warming.
Brendan Byrne, Junjie Liu, Yonghong Yi, Abhishek Chatterjee, Sourish Basu, Rui Cheng, Russell Doughty, Frédéric Chevallier, Kevin W. Bowman, Nicholas C. Parazoo, David Crisp, Xing Li, Jingfeng Xiao, Stephen Sitch, Bertrand Guenet, Feng Deng, Matthew S. Johnson, Sajeev Philip, Patrick C. McGuire, and Charles E. Miller
Biogeosciences, 19, 4779–4799, https://doi.org/10.5194/bg-19-4779-2022, https://doi.org/10.5194/bg-19-4779-2022, 2022
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Plants draw CO2 from the atmosphere during the growing season, while respiration releases CO2 to the atmosphere throughout the year, driving seasonal variations in atmospheric CO2 that can be observed by satellites, such as the Orbiting Carbon Observatory 2 (OCO-2). Using OCO-2 XCO2 data and space-based constraints on plant growth, we show that permafrost-rich northeast Eurasia has a strong seasonal release of CO2 during the autumn, hinting at an unexpectedly large respiration signal from soils.
Valery A. Isidorov and Andrej A. Zaitsev
Biogeosciences, 19, 4715–4746, https://doi.org/10.5194/bg-19-4715-2022, https://doi.org/10.5194/bg-19-4715-2022, 2022
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Biogenic volatile organic compounds (VOCs) play a critical role in earth-system processes: they are
main playersin the formation of tropospheric O3 and secondary aerosols, which have a significant impact on climate, human health and crops. A complex mixture of VOCs, formed as a result of physicochemical and biological processes, is released into the atmosphere from the forest floor. This review presents data on the composition of VOCs and contribution of various processes to their emissions.
David S. McLagan, Harald Biester, Tomas Navrátil, Stephan M. Kraemer, and Lorenz Schwab
Biogeosciences, 19, 4415–4429, https://doi.org/10.5194/bg-19-4415-2022, https://doi.org/10.5194/bg-19-4415-2022, 2022
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Spruce and larch trees are effective archiving species for historical atmospheric mercury using growth rings of bole wood. Mercury stable isotope analysis proved an effective tool to characterise industrial mercury signals and assess mercury uptake pathways (leaf uptake for both wood and bark) and mercury cycling within the trees. These data detail important information for understanding the mercury biogeochemical cycle particularly in forest systems.
Xin Yu, René Orth, Markus Reichstein, Michael Bahn, Anne Klosterhalfen, Alexander Knohl, Franziska Koebsch, Mirco Migliavacca, Martina Mund, Jacob A. Nelson, Benjamin D. Stocker, Sophia Walther, and Ana Bastos
Biogeosciences, 19, 4315–4329, https://doi.org/10.5194/bg-19-4315-2022, https://doi.org/10.5194/bg-19-4315-2022, 2022
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Identifying drought legacy effects is challenging because they are superimposed on variability driven by climate conditions in the recovery period. We develop a residual-based approach to quantify legacies on gross primary productivity (GPP) from eddy covariance data. The GPP reduction due to legacy effects is comparable to the concurrent effects at two sites in Germany, which reveals the importance of legacy effects. Our novel methodology can be used to quantify drought legacies elsewhere.
Anders Lindroth, Norbert Pirk, Ingibjörg S. Jónsdóttir, Christian Stiegler, Leif Klemedtsson, and Mats B. Nilsson
Biogeosciences, 19, 3921–3934, https://doi.org/10.5194/bg-19-3921-2022, https://doi.org/10.5194/bg-19-3921-2022, 2022
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We measured the fluxes of carbon dioxide and methane between a moist moss tundra and the atmosphere on Svalbard in order to better understand how such ecosystems are affecting the climate and vice versa. We found that the system was a small sink of carbon dioxide and a small source of methane. These fluxes are small in comparison with other tundra ecosystems in the high Arctic. Analysis of temperature sensitivity showed that respiration was more sensitive than photosynthesis above about 6 ℃.
Phillip Papastefanou, Christian S. Zang, Zlatan Angelov, Aline Anderson de Castro, Juan Carlos Jimenez, Luiz Felipe Campos De Rezende, Romina C. Ruscica, Boris Sakschewski, Anna A. Sörensson, Kirsten Thonicke, Carolina Vera, Nicolas Viovy, Celso Von Randow, and Anja Rammig
Biogeosciences, 19, 3843–3861, https://doi.org/10.5194/bg-19-3843-2022, https://doi.org/10.5194/bg-19-3843-2022, 2022
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The Amazon rainforest has been hit by multiple severe drought events. In this study, we assess the severity and spatial extent of the extreme drought years 2005, 2010 and 2015/16 in the Amazon. Using nine different precipitation datasets and three drought indicators we find large differences in drought stress across the Amazon region. We conclude that future studies should use multiple rainfall datasets and drought indicators when estimating the impact of drought stress in the Amazon region.
Haiyang Shi, Geping Luo, Olaf Hellwich, Mingjuan Xie, Chen Zhang, Yu Zhang, Yuangang Wang, Xiuliang Yuan, Xiaofei Ma, Wenqiang Zhang, Alishir Kurban, Philippe De Maeyer, and Tim Van de Voorde
Biogeosciences, 19, 3739–3756, https://doi.org/10.5194/bg-19-3739-2022, https://doi.org/10.5194/bg-19-3739-2022, 2022
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A number of studies have been conducted by using machine learning approaches to simulate carbon fluxes. We performed a meta-analysis of these net ecosystem exchange (NEE) simulations. Random forests and support vector machines performed better than other algorithms. Models with larger timescales had a lower accuracy. For different plant functional types (PFTs), there were significant differences in the predictors used and their effects on model accuracy.
Siqi Li, Wei Zhang, Xunhua Zheng, Yong Li, Shenghui Han, Rui Wang, Kai Wang, Zhisheng Yao, Chunyan Liu, and Chong Zhang
Biogeosciences, 19, 3001–3019, https://doi.org/10.5194/bg-19-3001-2022, https://doi.org/10.5194/bg-19-3001-2022, 2022
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The CNMM–DNDC model was modified to simulate ammonia volatilization (AV) from croplands. AV from cultivated uplands followed the first-order kinetics, which was jointly regulated by the factors of soil properties and meteorological conditions. AV simulation from rice paddy fields was improved by incorporating Jayaweera–Mikkelsen mechanisms. The modified model performed well in simulating the observed cumulative AV measured from 63 fertilization events in China.
Matthias Volk, Matthias Suter, Anne-Lena Wahl, and Seraina Bassin
Biogeosciences, 19, 2921–2937, https://doi.org/10.5194/bg-19-2921-2022, https://doi.org/10.5194/bg-19-2921-2022, 2022
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Because soils are an important sink for greenhouse gasses, we subjected sub-alpine grassland to a six-level climate change treatment.
Two independent methods showed that at warming > 1.5 °C the grassland ecosystem lost ca. 14 % or ca. 1 kg C m−2 in 5 years.
This shrinking of the terrestrial C sink implies a substantial positive feedback to the atmospheric greenhouse effect.
It is likely that this dramatic C loss is a transient effect before a new, climate-adjusted steady state is reached.
Johan A. Eckdahl, Jeppe A. Kristensen, and Daniel B. Metcalfe
Biogeosciences, 19, 2487–2506, https://doi.org/10.5194/bg-19-2487-2022, https://doi.org/10.5194/bg-19-2487-2022, 2022
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This study found climate to be a driving force for increasing per area emissions of greenhouse gases and removal of important nutrients from high-latitude forests due to wildfire. It used detailed direct measurements over a large area to uncover patterns and mechanisms of restructuring of forest carbon and nitrogen pools that are extrapolatable to larger regions. It also takes a step forward in filling gaps in global knowledge of northern forest response to climate-change-strengthened wildfires.
Sparkle L. Malone, Youmi Oh, Kyle A. Arndt, George Burba, Roisin Commane, Alexandra R. Contosta, Jordan P. Goodrich, Henry W. Loescher, Gregory Starr, and Ruth K. Varner
Biogeosciences, 19, 2507–2522, https://doi.org/10.5194/bg-19-2507-2022, https://doi.org/10.5194/bg-19-2507-2022, 2022
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To understand the CH4 flux potential of natural ecosystems and agricultural lands in the United States of America, a multi-scale CH4 observation network focused on CH4 flux rates, processes, and scaling methods is required. This can be achieved with a network of ground-based observations that are distributed based on climatic regions and land cover.
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Short summary
Forests face increased exposure to “compound soil and atmospheric drought” (CSAD) events due to global warming. We examined the impacts and drivers of CO2 fluxes during CSAD events at multiple layers of a deciduous forest over 18 years. Results showed reduced net ecosystem productivity and forest-floor respiration during CSAD events, mainly driven by soil and atmospheric drought. This unpredictability in forest CO2 fluxes jeopardises reforestation projects aimed at mitigating CO2 emissions.
Forests face increased exposure to “compound soil and atmospheric drought” (CSAD) events due to...
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