Search

Your search keyword '"Knohl, Alexander"' showing total 572 results
Start Over Author "Knohl, Alexander"
572 results on '"Knohl, Alexander"'

1. Recurrent Neural Networks for Modelling Gross Primary Production

Author

Montero, David, Mahecha, Miguel D., Martinuzzi, Francesco, Aybar, César, Klosterhalfen, Anne, Knohl, Alexander, Koebsch, Franziska, Anaya, Jesús, and Wieneke, Sebastian

Subjects
Computer Science - Machine Learning
Abstract

Accurate quantification of Gross Primary Production (GPP) is crucial for understanding terrestrial carbon dynamics. It represents the largest atmosphere-to-land CO$_2$ flux, especially significant for forests. Eddy Covariance (EC) measurements are widely used for ecosystem-scale GPP quantification but are globally sparse. In areas lacking local EC measurements, remote sensing (RS) data are typically utilised to estimate GPP after statistically relating them to in-situ data. Deep learning offers novel perspectives, and the potential of recurrent neural network architectures for estimating daily GPP remains underexplored. This study presents a comparative analysis of three architectures: Recurrent Neural Networks (RNNs), Gated Recurrent Units (GRUs), and Long-Short Term Memory (LSTMs). Our findings reveal comparable performance across all models for full-year and growing season predictions. Notably, LSTMs outperform in predicting climate-induced GPP extremes. Furthermore, our analysis highlights the importance of incorporating radiation and RS inputs (optical, temperature, and radar) for accurate GPP predictions, particularly during climate extremes., Comment: Accepted at IGARSS24

Published
2024

2. Leaf-level coordination principles propagate to the ecosystem scale.

Author

Gomarasca, Ulisse, Migliavacca, Mirco, Kattge, Jens, Nelson, Jacob, Niinemets, Ülo, Wirth, Christian, Cescatti, Alessandro, Bahn, Michael, Nair, Richard, Acosta, Alicia, Arain, M, Beloiu, Mirela, Black, T, Bruun, Hans, Bucher, Solveig, Buchmann, Nina, Byun, Chaeho, Carrara, Arnaud, Conte, Adriano, da Silva, Ana, Duveiller, Gregory, Fares, Silvano, Ibrom, Andreas, Knohl, Alexander, Komac, Benjamin, Limousin, Jean-Marc, Lusk, Christopher, Mahecha, Miguel, Martini, David, Minden, Vanessa, Montagnani, Leonardo, Mori, Akira, Onoda, Yusuke, Peñuelas, Josep, Perez-Priego, Oscar, Poschlod, Peter, Powell, Thomas, Reich, Peter, Šigut, Ladislav, van Bodegom, Peter, Walther, Sophia, Wohlfahrt, Georg, Wright, Ian, and Reichstein, Markus

Subjects
Ecosystem, Plants, Climate Change, Plant Leaves, Phenotype
Abstract

Fundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether similar trade-offs propagate to the ecosystem level. Here, we test whether trait correlation patterns predicted by three well-known leaf- and plant-level coordination theories - the leaf economics spectrum, the global spectrum of plant form and function, and the least-cost hypothesis - are also observed between community mean traits and ecosystem processes. We combined ecosystem functional properties from FLUXNET sites, vegetation properties, and community mean plant traits into three corresponding principal component analyses. We find that the leaf economics spectrum (90 sites), the global spectrum of plant form and function (89 sites), and the least-cost hypothesis (82 sites) all propagate at the ecosystem level. However, we also find evidence of additional scale-emergent properties. Evaluating the coordination of ecosystem functional properties may aid the development of more realistic global dynamic vegetation models with critical empirical data, reducing the uncertainty of climate change projections.

Published
2023

6. Joint optimization of land carbon uptake and albedo can help achieve moderate instantaneous and long-term cooling effects

Author

Graf, Alexander, Wohlfahrt, Georg, Aranda-Barranco, Sergio, Arriga, Nicola, Brümmer, Christian, Ceschia, Eric, Ciais, Philippe, Desai, Ankur R., Di Lonardo, Sara, Gharun, Mana, Grünwald, Thomas, Hörtnagl, Lukas, Kasak, Kuno, Klosterhalfen, Anne, Knohl, Alexander, Kowalska, Natalia, Leuchner, Michael, Lindroth, Anders, Mauder, Matthias, Migliavacca, Mirco, Morel, Alexandra C., Pfennig, Andreas, Poorter, Hendrik, Terán, Christian Poppe, Reitz, Oliver, Rebmann, Corinna, Sanchez-Azofeifa, Arturo, Schmidt, Marius, Šigut, Ladislav, Tomelleri, Enrico, Yu, Ke, Varlagin, Andrej, and Vereecken, Harry

Published
2023
Full Text
View/download PDF

7. Multifunctionality of temperate alley-cropping agroforestry outperforms open cropland and grassland

Author

Veldkamp, Edzo, Schmidt, Marcus, Markwitz, Christian, Beule, Lukas, Beuschel, René, Biertümpfel, Andrea, Bischel, Xenia, Duan, Xiaohong, Gerjets, Rowena, Göbel, Leonie, Graß, Rüdiger, Guerra, Victor, Heinlein, Florian, Komainda, Martin, Langhof, Maren, Luo, Jie, Potthoff, Martin, van Ramshorst, Justus G. V., Rudolf, Carolin, Seserman, Diana-Maria, Shao, Guodong, Siebicke, Lukas, Svoboda, Nikolai, Swieter, Anita, Carminati, Andrea, Freese, Dirk, Graf, Torsten, Greef, Jörg M., Isselstein, Johannes, Jansen, Martin, Karlovsky, Petr, Knohl, Alexander, Lamersdorf, Norbert, Priesack, Eckart, Wachendorf, Christine, Wachendorf, Michael, and Corre, Marife D.

Published
2023
Full Text
View/download PDF

9. The three major axes of terrestrial ecosystem function

Author

Migliavacca, Mirco, Musavi, Talie, Mahecha, Miguel D, Nelson, Jacob A, Knauer, Jürgen, Baldocchi, Dennis D, Perez-Priego, Oscar, Christiansen, Rune, Peters, Jonas, Anderson, Karen, Bahn, Michael, Black, T Andrew, Blanken, Peter D, Bonal, Damien, Buchmann, Nina, Caldararu, Silvia, Carrara, Arnaud, Carvalhais, Nuno, Cescatti, Alessandro, Chen, Jiquan, Cleverly, Jamie, Cremonese, Edoardo, Desai, Ankur R, El-Madany, Tarek S, Farella, Martha M, Fernández-Martínez, Marcos, Filippa, Gianluca, Forkel, Matthias, Galvagno, Marta, Gomarasca, Ulisse, Gough, Christopher M, Göckede, Mathias, Ibrom, Andreas, Ikawa, Hiroki, Janssens, Ivan A, Jung, Martin, Kattge, Jens, Keenan, Trevor F, Knohl, Alexander, Kobayashi, Hideki, Kraemer, Guido, Law, Beverly E, Liddell, Michael J, Ma, Xuanlong, Mammarella, Ivan, Martini, David, Macfarlane, Craig, Matteucci, Giorgio, Montagnani, Leonardo, Pabon-Moreno, Daniel E, Panigada, Cinzia, Papale, Dario, Pendall, Elise, Penuelas, Josep, Phillips, Richard P, Reich, Peter B, Rossini, Micol, Rotenberg, Eyal, Scott, Russell L, Stahl, Clement, Weber, Ulrich, Wohlfahrt, Georg, Wolf, Sebastian, Wright, Ian J, Yakir, Dan, Zaehle, Sönke, and Reichstein, Markus

Subjects
Life on Land, Carbon Cycle, Carbon Dioxide, Climate, Datasets as Topic, Ecosystem, Humidity, Plants, Principal Component Analysis, Water Cycle, General Science & Technology
Abstract

The leaf economics spectrum1,2 and the global spectrum of plant forms and functions3 revealed fundamental axes of variation in plant traits, which represent different ecological strategies that are shaped by the evolutionary development of plant species2. Ecosystem functions depend on environmental conditions and the traits of species that comprise the ecological communities4. However, the axes of variation of ecosystem functions are largely unknown, which limits our understanding of how ecosystems respond as a whole to anthropogenic drivers, climate and environmental variability4,5. Here we derive a set of ecosystem functions6 from a dataset of surface gas exchange measurements across major terrestrial biomes. We find that most of the variability within ecosystem functions (71.8%) is captured by three key axes. The first axis reflects maximum ecosystem productivity and is mostly explained by vegetation structure. The second axis reflects ecosystem water-use strategies and is jointly explained by variation in vegetation height and climate. The third axis, which represents ecosystem carbon-use efficiency, features a gradient related to aridity, and is explained primarily by variation in vegetation structure. We show that two state-of-the-art land surface models reproduce the first and most important axis of ecosystem functions. However, the models tend to simulate more strongly correlated functions than those observed, which limits their ability to accurately predict the full range of responses to environmental changes in carbon, water and energy cycling in terrestrial ecosystems7,8.

Published
2021

10. Detection and attribution of an anomaly in terrestrial photosynthesis in Europe during the COVID-19 lockdown

Author

Tang, Angela Che Ing, Flechard, Christophe R., Arriga, Nicola, Papale, Dario, Stoy, Paul C., Buchmann, Nina, Cuntz, Matthias, Douros, John, Fares, Silvano, Knohl, Alexander, Šigut, Ladislav, Simioni, Guillaume, Timmermans, Renske, Grünwald, Thomas, Ibrom, Andreas, Loubet, Benjamin, Mammarella, Ivan, Belelli Marchesini, Luca, Nilsson, Mats, Peichl, Matthias, Rebmann, Corinna, Schmidt, Marius, Bernhofer, Christian, Berveiller, Daniel, Cremonese, Edoardo, El-Madany, Tarek S., Gharun, Mana, Gianelle, Damiano, Hörtnagl, Lukas, Roland, Marilyn, Varlagin, Andrej, Fu, Zheng, Heinesch, Bernard, Janssens, Ivan, Kowalska, Natalia, Dušek, Jiří, Gerosa, Giacomo, Mölder, Meelis, Tuittila, Eeva-Stiina, and Loustau, Denis

Published
2023
Full Text
View/download PDF

12. The pantropical response of soil moisture to El Niño

Author

Solander, Kurt C, Newman, Brent D, de Araujo, Alessandro Carioca, Barnard, Holly R, Berry, Z Carter, Bonal, Damien, Bretfeld, Mario, Burban, Benoit, Candido, Luiz Antonio, Célleri, Rolando, Chambers, Jeffery Q, Christoffersen, Bradley O, Detto, Matteo, Dorigo, Wouter A, Ewers, Brent E, Ferreira, Savio José Filgueiras, Knohl, Alexander, Leung, L Ruby, McDowell, Nate G, Miller, Gretchen R, Monteiro, Maria Terezinha Ferreira, Moore, Georgianne W, Negron-Juarez, Robinson, Saleska, Scott R, Stiegler, Christian, Tomasella, Javier, and Xu, Chonggang

Subjects
Earth Sciences, Oceanography, Climate Action, Physical Geography and Environmental Geoscience, Civil Engineering, Environmental Engineering, Hydrology, Physical geography and environmental geoscience, Geomatic engineering
Abstract

The 2015-2016 El Niño event ranks as one of the most severe on record in terms of the magnitude and extent of sea surface temperature (SST) anomalies generated in the tropical Pacific Ocean. Corresponding global impacts on the climate were expected to rival, or even surpass, those of the 1997-1998 severe El Niño event, which had SST anomalies that were similar in size. However, the 2015-2016 event failed to meet expectations for hydrologic change in many areas, including those expected to receive well above normal precipitation. To better understand how climate anomalies during an El Niño event impact soil moisture, we investigate changes in soil moisture in the humid tropics (between ±25ĝˆ ) during the three most recent super El Niño events of 1982-1983, 1997-1998 and 2015-2016, using data from the Global Land Data Assimilation System (GLDAS). First, we use in situ soil moisture observations obtained from 16 sites across five continents to validate and bias-correct estimates from GLDAS (r2Combining double low line0.54). Next, we apply a k-means cluster analysis to the soil moisture estimates during the El Niño mature phase, resulting in four groups of clustered data. The strongest and most consistent decreases in soil moisture occur in the Amazon basin and maritime southeastern Asia, while the most consistent increases occur over eastern Africa. In addition, we compare changes in soil moisture to both precipitation and evapotranspiration, which showed a lack of agreement in the direction of change between these variables and soil moisture most prominently in the southern Amazon basin, the Sahel and mainland southeastern Asia. Our results can be used to improve estimates of spatiotemporal differences in El Niño impacts on soil moisture in tropical hydrology and ecosystem models at multiple scales..

Published
2020

13. Balancing economic and ecological functions in smallholder and industrial oil palm plantations

Author

Wenzel, Arne, primary, Westphal, Catrin, additional, Ballauff, Johannes, additional, Berkelmann, Dirk, additional, Brambach, Fabian, additional, Buchori, Damayanti, additional, Camarretta, Nicolò, additional, Corre, Marife D., additional, Daniel, Rolf, additional, Darras, Kevin, additional, Erasmi, Stefan, additional, Formaglio, Greta, additional, Hölscher, Dirk, additional, Iddris, Najeeb Al-Amin, additional, Irawan, Bambang, additional, Knohl, Alexander, additional, Kotowska, Martyna M., additional, Krashevska, Valentyna, additional, Kreft, Holger, additional, Mulyani, Yeni, additional, Mußhoff, Oliver, additional, Paterno, Gustavo B., additional, Polle, Andrea, additional, Potapov, Anton, additional, Röll, Alexander, additional, Scheu, Stefan, additional, Schlund, Michael, additional, Schneider, Dominik, additional, Sibhatu, Kibrom T., additional, Stiegler, Christian, additional, Sundawati, Leti, additional, Tjoa, Aiyen, additional, Tscharntke, Teja, additional, Veldkamp, Edzo, additional, Waite, Pierre-André, additional, Wollni, Meike, additional, Zemp, Delphine Clara, additional, and Grass, Ingo, additional

Published
2024
Full Text
View/download PDF

14. Altered energy partitioning across terrestrial ecosystems in the European drought year 2018

Author

Graf, Alexander, Klosterhalfen, Anne, Arriga, Nicola, Bernhofer, Christian, Bogena, Heye, Bornet, Frédéric, Brüggemann, Nicolas, Brümmer, Christian, Buchmann, Nina, Chi, Jinshu, Chipeaux, Christophe, Cremonese, Edoardo, Cuntz, Matthias, Dušek, Jiří, El-Madany, Tarek S., Fares, Silvano, Fischer, Milan, Foltýnová, Lenka, Gharun, Mana, Ghiasi, Shiva, Gielen, Bert, Gottschalk, Pia, Grünwald, Thomas, Heinemann, Günther, Heinesch, Bernard, Heliasz, Michal, Holst, Jutta, Hörtnagl, Lukas, Ibrom, Andreas, Ingwersen, Joachim, Jurasinski, Gerald, Klatt, Janina, Knohl, Alexander, Koebsch, Franziska, Konopka, Jan, Korkiakoski, Mika, Kowalska, Natalia, Kremer, Pascal, Kruijt, Bart, Lafont, Sebastien, Léonard, Joël, De Ligne, Anne, Longdoz, Bernard, Loustau, Denis, Magliulo, Vincenzo, Mammarella, Ivan, Manca, Giovanni, Mauder, Matthias, Migliavacca, Mirco, Mölder, Meelis, Neirynck, Johan, Ney, Patrizia, Nilsson, Mats, Paul-Limoges, Eugénie, Peichl, Matthias, Pitacco, Andrea, Poyda, Arne, Rebmann, Corinna, Roland, Marilyn, Sachs, Torsten, Schmidt, Marius, Schrader, Frederik, Siebicke, Lukas, Šigut, Ladislav, Tuittila, Eeva-Stiina, Varlagin, Andrej, Vendrame, Nadia, Vincke, Caroline, Völksch, Ingo, Weber, Stephan, Wille, Christian, Wizemann, Hans-Dieter, Zeeman, Matthias, and Vereecken, Harry

Published
2020

15. Sensitivity of gross primary productivity to climatic drivers during the summer drought of 2018 in Europe

Author

Fu, Zheng, Ciais, Philippe, Bastos, Ana, Stoy, Paul C., Yang, Hui, Green, Julia K., Wang, Bingxue, Yu, Kailiang, Huang, Yuanyuan, Knohl, Alexander, Šigut, Ladislav, Gharun, Mana, Cuntz, Matthias, Arriga, Nicola, Roland, Marilyn, Peichl, Matthias, Migliavacca, Mirco, Cremonese, Edoardo, Varlagin, Andrej, Brümmer, Christian, de la Motte, Louis Gourlez, Fares, Silvano, Buchmann, Nina, El-Madany, Tarek S., Pitacco, Andrea, Vendrame, Nadia, Li, Zhaolei, Vincke, Caroline, Magliulo, Enzo, and Koebsch, Franziska

Published
2020

16. Climate and soils together regulate photosynthetic carbon isotope discrimination within C3 plants worldwide

Author

Cornwell, William K, Wright, Ian J, Turner, Joel, Maire, Vincent, Barbour, Margaret M, Cernusak, Lucas A, Dawson, Todd, Ellsworth, David, Farquhar, Graham D, Griffiths, Howard, Keitel, Claudia, Knohl, Alexander, Reich, Peter B, Williams, David G, Bhaskar, Radika, Cornelissen, Johannes HC, Richards, Anna, Schmidt, Susanne, Valladares, Fernando, Körner, Christian, Schulze, Ernst‐Detlef, Buchmann, Nina, and Santiago, Louis S

Subjects
Climate Action, carbon isotopes, environmental drivers, global, leaf traits, leaves, soil, Ecology
Abstract

Aim: Within C3 plants, photosynthesis is a balance between CO2 supply from the atmosphere via stomata and demand by enzymes within chloroplasts. This process is dynamic and a complex but crucial aspect of photosynthesis. We sought to understand the spatial pattern in CO2 supply–demand balance on a global scale, via analysis of stable isotopes of carbon within leaves (Δ13C), which provide an integrative record of CO2 drawdown during photosynthesis. LocationGlobal. Time period1951–2011. Major taxa studiedVascular plants. Methods: We assembled a database of leaf carbon isotope ratios containing 3,979 species–site combinations from across the globe, including 3,645 for C3 species. We examined a wide array of potential climate and soil drivers of variation in Δ13C. Results: The strongest drivers of carbon isotope discrimination at the global scale included atmospheric pressure, potential evapotranspiration and soil pH, which explained 44% of the variation in Δ13C. Addition of eight more climate and soil variables (each explaining small but highly significant amounts of variation) increased the explained variation to 60%. On top of this, the largest plant trait effect was leaf nitrogen per area, which explained 11% of Δ13C variation. Main conclusions: By considering variation in Δ13C at a considerably larger scale than previously, we were able to identify and quantify key drivers in CO2 supply–demand balance previously unacknowledged. Of special note is the key role of soil properties, with greater discrimination on low-pH and high-silt soils. Unlike other plant traits, which show typically wide variation within sets of coexisting species, the global pattern in carbon stable isotope ratios is much more conservative; there is relatively narrow variation in time-integrated CO2 concentrations at the site of carboxylation among plants in a given soil and climate.

Published
2018

18. Dynamics in CO2 uptake, growth, and mortality of an old-growth temperate forest under drought stress

Author

Koebsch, Franziska, primary, Klosterhalfen, Anne, additional, Emad, Anas, additional, Mund, Martina, additional, Ammer, Christian, additional, Dietenberger, Steffen, additional, Donfack, Laura, additional, Heidenreich, Marius, additional, Mueller, Marlin M., additional, Seidel, Dominik, additional, Thiel, Christian, additional, Tiedemann, Frank, additional, and Knohl, Alexander, additional

Published
2024
Full Text
View/download PDF

20. X-BASE: the first terrestrial carbon and water flux products from an extended data-driven scaling framework, FLUXCOM-X

Author

Nelson, Jacob A., primary, Walther, Sophia, additional, Gans, Fabian, additional, Kraft, Basil, additional, Weber, Ulrich, additional, Novick, Kimberly, additional, Buchmann, Nina, additional, Migliavacca, Mirco, additional, Wohlfahrt, Georg, additional, Šigut, Ladislav, additional, Ibrom, Andreas, additional, Papale, Dario, additional, Göckede, Mathias, additional, Duveiller, Gregory, additional, Knohl, Alexander, additional, Hörtnagl, Lukas, additional, Scott, Russell L., additional, Zhang, Weijie, additional, Hamdi, Zayd Mahmoud, additional, Reichstein, Markus, additional, Aranda-Barranco, Sergio, additional, Ardö, Jonas, additional, Op de Beeck, Maarten, additional, Billdesbach, Dave, additional, Bowling, David, additional, Bracho, Rosvel, additional, Brümmer, Christian, additional, Camps-Valls, Gustau, additional, Chen, Shiping, additional, Cleverly, Jamie Rose, additional, Desai, Ankur, additional, Dong, Gang, additional, El-Madany, Tarek S., additional, Euskirchen, Eugenie Susanne, additional, Feigenwinter, Iris, additional, Galvagno, Marta, additional, Gerosa, Giacomo, additional, Gielen, Bert, additional, Goded, Ignacio, additional, Goslee, Sarah, additional, Gough, Christopher Michael, additional, Heinesch, Bernard, additional, Ichii, Kazuhito, additional, Jackowicz-Korczynski, Marcin Antoni, additional, Klosterhalfen, Anne, additional, Knox, Sara, additional, Kobayashi, Hideki, additional, Kohonen, Kukka-Maaria, additional, Korkiakoski, Mika, additional, Mammarella, Ivan, additional, Mana, Gharun, additional, Marzuoli, Riccardo, additional, Matamala, Roser, additional, Metzger, Stefan, additional, Montagnani, Leonardo, additional, Nicolini, Giacomo, additional, O'Halloran, Thomas, additional, Ourcival, Jean-Marc, additional, Peichl, Matthias, additional, Pendall, Elise, additional, Ruiz Reverter, Borja, additional, Roland, Marilyn, additional, Sabbatini, Simone, additional, Sachs, Torsten, additional, Schmidt, Marius, additional, Schwalm, Christopher R., additional, Shekhar, Ankit, additional, Silberstein, Richard, additional, Silveira, Maria Lucia, additional, Spano, Donatella, additional, Tagesson, Torbern, additional, Tramontana, Gianluca, additional, Trotta, Carlo, additional, Turco, Fabio, additional, Vesala, Timo, additional, Vincke, Caroline, additional, Vitale, Domenico, additional, Vivoni, Enrique R., additional, Wang, Yi, additional, Woodgate, William, additional, Yepez, Enrico A., additional, Zhang, Junhui, additional, Zona, Donatella, additional, and Jung, Martin, additional

Published
2024
Full Text
View/download PDF

25. Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

Author

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, Reichstein, Markus, Ribeca, Alessio, van Ingen, Catharine, Vuichard, Nicolas, Zhang, Leiming, Amiro, Brian, Ammann, Christof, Arain, M. Altaf, Ardö, 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, Brümmer, 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, Dufrêne, Eric, Dunn, Allison, Dušek, Jiří, 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, Grünwald, Thomas, Hammerle, Albin, Han, Shijie, Han, Xingguo, Hansen, Birger Ulf, Hanson, Chad, Hatakka, Juha, He, Yongtao, Hehn, Markus, Heinesch, Bernard, Hinko-Najera, Nina, Hörtnagl, Lukas, Hutley, Lindsay, Ibrom, Andreas, Ikawa, Hiroki, Jackowicz-Korczynski, Marcin, Janouš, 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, López-Ballesteros, Ana, López-Blanco, Efrén, Loubet, Benjamin, Loustau, Denis, Lucas-Moffat, Antje, Lüers, 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, Jørgen 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, Üllar, Raz-Yaseef, Naama, Rebmann, Corinna, Reed, David, de Dios, Victor Resco, Restrepo-Coupe, Natalia, Reverter, Borja R., Roland, Marilyn, Sabbatini, Simone, Sachs, Torsten, Saleska, Scott R., Sánchez-Cañete, Enrique P., Sanchez-Mejia, Zulia M., Schmid, Hans Peter, Schmidt, Marius, Schneider, Karl, Schrader, Frederik, Schroder, Ivan, Scott, Russell L., Sedlák, Pavel, Serrano-Ortíz, Penélope, Shao, Changliang, Shi, Peili, Shironya, Ivan, Siebicke, Lukas, Šigut, 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, 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, and Papale, Dario

Published
2021
Full Text
View/download PDF

26. Simulated effects of canopy structural complexity on forest productivity

Author

Toda, Motomu, Knohl, Alexander, Luyssaert, Sebastiaan, Hara, Toshihiko, and Systems Ecology

Subjects
Atmosphere–vegetation dynamics model (MINoSGI), Diffuse light, Forestry, Management, Monitoring, Policy and Law, In-canopy microclimate, Old-growth forest, Sunlit and shaded leaves, Canopy photosynthesis, Nature and Landscape Conservation, SDG 15 - Life on Land
Abstract

Late-successional unmanaged forests (or old-growth forests) are important terrestrial carbon sinks. Their structurally complex features have been hypothesized to strongly affect forest productivity. However, the mechanisms through which structural complexity influences forest productivity remain unresolved. Here, we report a set of idealised simulations in boreal, sub-boreal, cool-temperate, warm-temperate and tropical forests using a dynamic model of atmosphere and vegetation interactions (Multilayered Integrated Numerical Model of Surface Physics–Growing Plants Interaction, MINoSGI). We aimed to elucidate the effects of tree–size and canopy structural complexity on stand-scale gross primary productivity (GPP) of old-growth forests over 300-year time series. We assumed the tree-size structures of mature old-growth forests as the initial conditions of the simulations. We focused on three different developmental phases of the forests: 29–48 years (phase I), 77–96 years (phase II) and 277–296 years (phase III) from the start of the simulations. Phase I corresponds to an old-growth forest because of our settings of the initial conditions of the simulations, and phase III to a long-term resultant forest without recruitment or mortality. We show that, for a given biome-specific leaf area index (LAI) and individual foliage shape (η), the greatest difference in GPP (ΔGPP) between forests with the most and least structurally complex canopies was 263 g C/m−2(-|-) year−1 in phase I and II when old-growth forests with the most complex canopy structures sustained their complexity, equivalent to almost 13 % of the annual GPP. By contrast, the maximum difference in ΔGPP was reduced to 153 g C/m−2(-|-) year−1 in phase III, equivalent to 8 % of the annual GPP total because the complex canopy structures of old-growth forests without recruitment or mortality approached less multi-layered ones similar to those of less complex and managed forests. Our simulation results indicate that greater tree–size and canopy structural complexity is associated with a broader vertical distribution of foliage, supporting the localisation of leaves in multiple layers. This increases the efficacy of light usage, particularly for shaded leaves receiving only diffuse light within the canopy. As a consequence, for all forest biomes, an increase in in-canopy diffuse light increases GPP in forests with complex canopy structures due to an enhancement of light use efficiency (LUE) of shaded leaves. Overall, our results quantify one of the mechanisms underlying the effects of canopy structural complexity on forest productivity. Moreover, differences in foliage shape between forest biomes can add to uncertainties when predicting GPP based on simulation models. We, therefore, suggest that precise values of the biome-specific factors associated with canopy structure should be employed into simulation models of global carbon budgets.

Published
2023

29. Lower-cost eddy covariance for CO2 and H2O fluxes over grassland and agroforestry.

Author

Ramshorst, Justus G. V. van, Knohl, Alexander, Callejas-Rodelas, José Ángel, Clement, Robert, Hill, Timothy C., Siebicke, Lukas, and Markwitz, Christian

Subjects
*AGROFORESTRY, *GRASSLANDS, *EDDIES, *HEAT flux, *CORRECTION factors, *LATENT heat, *ATMOSPHERIC carbon dioxide
Abstract

Eddy covariance (EC) measurements can provide direct and non-invasive ecosystem measurements of the exchange of energy, water (H2O) and carbon dioxide (CO2). However, conventional eddy covariance (CON-EC) setups (ultrasonic anemometer and infrared gas analyser) can be expensive, which recently led to the development of lower-cost eddy covariance (LC-EC) setups. In the current study we test the performance of a LC-EC setup for CO2 and H2O flux measurements at an agroforestry and adjacent grassland site in a temperate ecosystem in northern Germany. The closed-path LC-EC setup was compared with a CON-EC setup using an enclosed-path gas analyser (LI-7200, LI-COR Inc., Lincoln, NE, USA). The LC-EC CO2 fluxes were lower compared to CON-EC by 7–13 % (R 2 = 0.91–0.95) and the latent heat fluxes were higher by 2–3 % in 2020 and 23 % in 2021 (R 2 = 0.84–0.90). The large difference between latent heat fluxes in 2021, seems to be a consequence of the lower LE fluxes measured by the CON-EC. Due to the slower response sensors of the LC-EC setup, the (co)spectra of the LC-EC were more attenuated in the high-frequency range compared to the CON-EC. This stronger attenuation of the LC-EC requires a larger spectral correction and as a consequence larger differences between spectral correction factors of different spectral correction methods. At the agroforestry site where the flux tower was taller compared to the grassland, the attenuation was lower, because the cospectrum peak and energy-containing eddies shift to lower frequencies which the LC-EC can measure. With the LC-EC and CON-EC systems was shown that the agroforestry site had a 2.3 times higher carbon uptake compared to the grassland site and both had an equal evapotranspiration when simultaneously measured for one month. Our results show that LC-EC has the potential to measure EC fluxes at various land-use systems for approximately 25 % of the costs of a CON-EC system. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

30. X-BASE: the first terrestrial carbon and water flux products from an extended data-driven scaling framework, FLUXCOM-X.

Author

Nelson, Jacob A., Walther, Sophia, Gans, Fabian, Kraft, Basil, Weber, Ulrich, Novick, Kimberly, Buchmann, Nina, Migliavacca, Mirco, Wohlfahrt, Georg, Šigut, Ladislav, Ibrom, Andreas, Papale, Dario, Göckede, Mathias, Duveiller, Gregory, Knohl, Alexander, Hörtnagl, Lukas, Scott, Russell L., Zhang, Weijie, Hamdi, Zayd Mahmoud, and Reichstein, Markus

Subjects
EVAPOTRANSPIRATION, CARBON cycle, INTERNATIONAL relations, MACHINE learning, CARBON, PIPELINE inspection
Abstract

Mapping in-situ eddy covariance measurements of terrestrial land-atmosphere fluxes to the globe is a key method for diagnosing the Earth system from a data-driven perspective. We describe the first global products (called X-BASE) from a newly implemented up-scaling framework, FLUXCOM-X. The X-BASE products comprise of estimates of CO 2 net ecosystem exchange (NEE), gross primary productivity (GPP) as well as evapotranspiration (ET) and, for the first time, a novel fully data-driven global transpiration product (ETT), at high spatial (0.05°) and temporal (hourly) resolution. X-BASE estimates the global NEE at -5.75 ± 0.33 Pg C ⋅ yr -1 for the period 2001–2020, showing a much higher consistency with independent atmospheric carbon cycle constraints compared to the previous versions of FLUXCOM. The improvement of global NEE was likely only possible thanks to the international effort to increase the precision and consistency of eddy covariance collection and processing pipelines, as well as to the extension of the measurements to more site-years resulting in a wider coverage of bio-climatic conditions. However, X-BASE global net ecosystem exchange shows a very low inter-annual variability, which is common to state-of-the-art data-driven flux products and remains a scientific challenge. With 125 ± 2.1 Pg C ⋅ yr -1 for the same period, X-BASE GPP is slightly higher than previous FLUXCOM estimates, mostly in temperate and boreal areas. X-BASE evapotranspiration amounts to 74.7x10³ ± 0.9x10³ km 3 globally for the years 2001–2020, but exceeds precipitation in many dry areas likely indicating overestimation in these regions. On average 57 % of evapotranspiration are estimated to be transpiration, in good agreement with isotope-based approaches, but higher than estimates from many land surface models. Despite considerable improvements to the previous up-scaling products, many further opportunities for development exist. Pathways of exploration include methodological choices in the selection and processing of eddy-covariance and satellite observations, their ingestion into the framework, and the configuration of machine learning methods. For this, the new FLUXCOM-X framework was specifically designed to have the necessary flexibility to experiment, diagnose, and converge to more accurate global flux estimates. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

31. X-BASE: the first terrestrial carbon and water flux products from an extended data-driven scaling framework, FLUXCOM-X.

Author

Nelson, Jacob A, Walther, Sophia, Gans, Fabian, Kraft, Basil, Weber, Ulrich, Novick, Kimberly, Buchmann, Nina, Migliavacca, Mirco, Wohlfahrt, Georg, Šigut, Ladislav, Ibrom, Andreas, Papale, Dario, Göckede, Mathias, Duveiller, Gregory, Knohl, Alexander, Hörtnagl, Lukas, Scott, Russell L., Weijie Zhang, Hamdi, Zayd Mahmoud, and Reichstein, Markus

Subjects
EVAPOTRANSPIRATION, CARBON cycle, INTERNATIONAL relations, MACHINE learning, CARBON, PIPELINE inspection
Abstract

Mapping in-situ eddy covariance measurements of terrestrial land-atmosphere fluxes to the globe is a key method for diagnosing the Earth system from a data-driven perspective. We describe the first global products (called X-BASE) from a newly implemented up-scaling framework, FLUXCOM-X. The X-BASE products comprise of estimates of CO2 net ecosystem exchange (NEE), gross primary productivity (GP P) as well as evapotranspiration (ET) and, for the first time, a novel fully data-driven global transpiration product (ETT ), at high spatial (0.05°) and temporal (hourly) resolution. X-BASE estimates the global NEE at -5.75 ± 0.33 P g C · yr−1 for the period 2001-2020, showing a much higher consistency with independent atmospheric carbon cycle constraints compared to the previous versions of FLUXCOM. The improvement of global NEE was likely only possible thanks to the international effort to increase the precision and consistency of eddy covariance collection and processing pipelines, as well as to the extension of the measurements to more site-years resulting in a wider coverage of bio-climatic conditions. However, X-BASE global net ecosystem exchange shows a very low inter-annual variability, which is common to state-of-the-art data-driven flux products and remains a scientific challenge. With 125 ± 2.1 P gC · yr−1 for the same period, X-BASE GP P is slightly higher than previous FLUXCOM estimates, mostly in temperate and boreal areas. X-BASE evapotranspiration amounts to 74.7x103 ± 0.9x103 km3 globally for the years 2001-2020, but exceeds precipitation in many dry areas likely indicating overestimation in these regions. On average 57% of evapotranspiration are estimated to be transpiration, in good agreement with isotope-based approaches, but higher than estimates from many land surface models. Despite considerable improvements to the previous up-scaling products, many further opportunities for development exist. Pathways of exploration include methodological choices in the selection and processing of eddy-covariance and satellite observations, their ingestion into the framework, and the configuration of machine learning methods. For this, the new FLUXCOM-X framework was specifically designed to have the necessary flexibility to experiment, diagnose, and converge to more accurate global flux estimates. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

34. Climate and soils together regulate photosynthetic carbon isotope discrimination within C 3 plants worldwide

Author

Cornwell, William K., Wright, Ian J., Turner, Joel, Maire, Vincent, Barbour, Margaret M., Cernusak, Lucas A., Dawson, Todd, Ellsworth, David, Farquhar, Graham D., Griffiths, Howard, Keitel, Claudia, Knohl, Alexander, Reich, Peter B., Williams, David G., Bhaskar, Radika, Cornelissen, Johannes H. C., Richards, Anna, Schmidt, Susanne, Valladares, Fernando, Körner, Christian, Schulze, Ernst-Detlef, Buchmann, Nina, and Santiago, Louis S.

Published
2018

37. The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

Author

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, Reichstein, Markus, Ribeca, Alessio, van Ingen, Catharine, Vuichard, Nicolas, Zhang, Leiming, Amiro, Brian, Ammann, Christof, Arain, M. Altaf, Ardö, 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, Brümmer, 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., Cinti, Bruno De, Grandcourt, Agnes de, Ligne, Anne De, De Oliveira, Raimundo C., Delpierre, Nicolas, Desai, Ankur R., Di Bella, Carlos Marcelo, Tommasi, Paul di, Dolman, Han, Domingo, Francisco, Dong, Gang, Dore, Sabina, Duce, Pierpaolo, Dufrêne, Eric, Dunn, Allison, Dušek, Jiří, 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, Grünwald, Thomas, Hammerle, Albin, Han, Shijie, Han, Xingguo, Hansen, Birger Ulf, Hanson, Chad, Hatakka, Juha, He, Yongtao, Hehn, Markus, Heinesch, Bernard, Hinko-Najera, Nina, Hörtnagl, Lukas, Hutley, Lindsay, Ibrom, Andreas, Ikawa, Hiroki, Jackowicz-Korczynski, Marcin, Janouš, 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, López-Ballesteros, Ana, López-Blanco, Efrén, Loubet, Benjamin, Loustau, Denis, Lucas-Moffat, Antje, Lüers, 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, Jørgen 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, Üllar, Raz-Yaseef, Naama, Rebmann, Corinna, Reed, David, Dios, Victor Resco de, Restrepo-Coupe, Natalia, Reverter, Borja R., Roland, Marilyn, Sabbatini, Simone, Sachs, Torsten, Saleska, Scott R., Sánchez-Cañete, Enrique P., Sanchez-Mejia, Zulia M., Schmid, Hans Peter, Schmidt, Marius, Schneider, Karl, Schrader, Frederik, Schroder, Ivan, Scott, Russell L., Sedlák, Pavel, Serrano-Ortíz, Penélope, Shao, Changliang, Shi, Peili, Shironya, Ivan, Siebicke, Lukas, Šigut, 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, 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, and Papale, Dario

Published
2020
Full Text
View/download PDF

39. Understanding the Stable Isotope Composition of Biosphere-Atmosphere CO 2 Exchange

Author

McDowell, Nate, Baldocchi, Dennis, Barbour, Margaret, Bickford, Chris, Cuntz, Matthias, Hanson, Dave, Knohl, Alexander, Powers, Heath, Rahn, Thomas, Randerson, Jim, Riley, William J, Still, Chris, Tu, Kevin, and Walcroft, Adrian

Subjects
atmosphere-biosphere interaction, carbon cycle, carbon dioxide, isotopic composition, stable isotope
Abstract

Stable isotopes of atmospheric carbon dioxide (CO2) contain a wealth of information regarding biosphere-atmosphere interactions. The carbon isotope ratio of CO2 (δ13C) reflects the terrestrial carbon cycle including processes of photosynthesis, respiration, and decomposition. The oxygen isotope ratio (δ18O) reflects terrestrial carbon and water coupling due to CO2-H2O oxygen exchange. Isotopic CO2 measurements, in combination with ecosystem-isotopic exchange models, allow for the quantification of patterns and mechanisms regulating terrestrial carbon and water cycles, as well as for hypothesis development, data interpretation, and forecasting. Isotopic measurements and models have evolved significantly over the past two decades, resulting in organizations that promote model-measurement networks, e.g., the U.S. National Science Foundation's Biosphere-Atmosphere Stable Isotope Network, the European Stable Isotopes in Biosphere-Atmosphere Exchange Network, and the U.S. National Environmental Observatory Network.

Published
2008

41. Trade-offs between multifunctionality and profit in tropical smallholder landscapes

Author

Grass, Ingo, Kubitza, Christoph, Krishna, Vijesh V., Corre, Marife D., Mußhoff, Oliver, Pütz, Peter, Drescher, Jochen, Rembold, Katja, Ariyanti, Eka Sulpin, Barnes, Andrew D., Brinkmann, Nicole, Brose, Ulrich, Brümmer, Bernhard, Buchori, Damayanti, Daniel, Rolf, Darras, Kevin F. A., Faust, Heiko, Fehrmann, Lutz, Hein, Jonas, Hennings, Nina, Hidayat, Purnama, Hölscher, Dirk, Jochum, Malte, Knohl, Alexander, Kotowska, Martyna M., Krashevska, Valentyna, Kreft, Holger, Leuschner, Christoph, Lobite, Neil Jun S., Panjaitan, Rawati, Polle, Andrea, Potapov, Anton M., Purnama, Edwine, Qaim, Matin, Röll, Alexander, Scheu, Stefan, Schneider, Dominik, Tjoa, Aiyen, Tscharntke, Teja, Veldkamp, Edzo, and Wollni, Meike

Published
2020
Full Text
View/download PDF

44. Temporal variation in nitrous oxide (N2O) fluxes from an oil palm plantation in Indonesia: An ecosystem‐scale analysis.

Author

Stiegler, Christian, Koebsch, Franziska, Ali, Ashehad Ashween, June, Tania, Veldkamp, Edzo, Corre, Marife D., Koks, Joost, Tjoa, Aiyen, and Knohl, Alexander

Subjects
OIL palm, NITROUS oxide, CARBONACEOUS aerosols, GAS dynamics, SOIL respiration, PLANTATIONS
Abstract

The rapidly growing areal extent of oil palm (Elaeis guineensis Jacq.) plantations and their high fertilizer input raises concerns about their role as substantial N2O sources. In this study, we present the first eddy covariance (EC) measurements of ecosystem‐scale N2O fluxes in an oil palm plantation and combine them with vented soil chamber measurements of point‐scale soil N2O fluxes. Based on EC measurements during the period August 2017 to April 2019, the studied oil palm plantation in the tropical lowlands of Jambi Province (Sumatra, Indonesia) is a high source of N2O, with average emission of 0.32 ± 0.003 g N2O‐N m−2 year−1 (149.85 ± 1.40 g CO2‐equivalent m−2 year−1). Compared to the EC‐based N2O flux, average chamber‐based soil N2O fluxes (0.16 ± 0.047 g N2O‐N m−2 year−1, 74.93 ± 23.41 g CO2‐equivalent m−2 year−1) are significantly (~49%, p < 0.05) lower, suggesting that important N2O pathways are not covered by the chamber measurements. Conventional chamber‐based N2O emission estimates from oil palm up‐scaled to ecosystem level might therefore be substantially underestimated. We show that the dynamic gas exchange of the oil palm canopy with the atmosphere and the oil palms' response to meteorological and soil conditions may play an important but yet widely unexplored role in the N2O budget of oil palm plantations. Diel pattern of N2O fluxes showed strong causal relationships with photosynthesis‐related variables, i.e. latent heat flux, incoming photosynthetically active radiation and gross primary productivity during day time, and ecosystem respiration and soil temperature during night time. At longer time scales (>2 days), soil temperature and water‐filled pore space gained importance on N2O flux variation. These results suggest a plant‐mediated N2O transport, providing important input for modelling approaches and strategies to mitigate the negative impact of N2O emissions from oil palm cultivation through appropriate site selection and management. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

46. Stress response and transformation processes initiated by the summer drought 2018 – a multi-scale study from the Hainich forest

Author

Koebsch, Franziska, primary, Mund, Martina, additional, Klosterhalfen, Anne, additional, Dietenberger, Steffen, additional, Donfack, Laura, additional, Heidenreich, Marius, additional, Markwitz, Christian, additional, Montero, David, additional, Thiel, Christian, additional, Tiedemann, Frank, additional, and Knohl, Alexander, additional

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results