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2. Multi-scale predictions of massive conifer mortality due to chronic temperature rise

Author

McDowell, NG, Williams, AP, Xu, C, Pockman, WT, Dickman, LT, Sevanto, S, Pangle, R, Limousin, J, Plaut, J, Mackay, DS, Ogee, J, Domec, JC, Allen, CD, Fisher, RA, Jiang, X, Muss, JD, Breshears, DD, Rauscher, SA, and Koven, C

Subjects
Good Health and Well Being, Atmospheric Sciences, Physical Geography and Environmental Geoscience, Environmental Science and Management
Abstract

Global temperature rise and extremes accompanying drought threaten forests and their associated climatic feedbacks. Our ability to accurately simulate drought-induced forest impacts remains highly uncertain in part owing to our failure to integrate physiological measurements, regional-scale models, and dynamic global vegetation models (DGVMs). Here we show consistent predictions of widespread mortality of needleleaf evergreen trees (NET) within Southwest USA by 2100 using state-of-the-art models evaluated against empirical data sets. Experimentally, dominant Southwest USA NET species died when they fell below predawn water potential (pd) thresholds (April-August mean) beyond which photosynthesis, hydraulic and stomatal conductance, and carbohydrate availability approached zero. The evaluated regional models accurately predicted NET pd, and 91% of predictions (10 out of 11) exceeded mortality thresholds within the twenty-first century due to temperature rise. The independent DGVMs predicted ≥50% loss of Northern Hemisphere NET by 2100, consistent with the NET findings for Southwest USA. Notably, the global models underestimated future mortality within Southwest USA, highlighting that predictions of future mortality within global models may be underestimates. Taken together, the validated regional predictions and the global simulations predict widespread conifer loss in coming decades under projected global warming.

Published
2016

4. Global maps of soil temperature

Author

Lembrechts, J. J. (Jonas J.), van den Hoogen, J. (Johan), Aalto, J. (Juha), Ashcroft, M. B. (Michael B.), De Frenne, P. (Pieter), Kemppinen, J. (Julia), Kopecky, M. (Martin), Luoto, M. (Miska), Maclean, I. M. (Ilya M. D.), Crowther, T. W. (Thomas W.), Bailey, J. J. (Joseph J.), Haesen, S. (Stef), Klinges, D. H. (David H.), Niittynen, P. (Pekka), Scheffers, B. R. (Brett R.), Van Meerbeek, K. (Koenraad), Aartsma, P. (Peter), Abdalaze, O. (Otar), Abedi, M. (Mehdi), Aerts, R. (Rien), Ahmadian, N. (Negar), Ahrends, A. (Antje), Alatalo, J. M. (Juha M.), Alexander, J. M. (Jake M.), Allonsius, C. N. (Camille Nina), Altman, J. (Jan), Ammann, C. (Christof), Andres, C. (Christian), Andrews, C. (Christopher), Ardo, J. (Jonas), Arriga, N. (Nicola), Arzac, A. (Alberto), Aschero, V. (Valeria), Assis, R. L. (Rafael L.), Assmann, J. J. (Jakob Johann), Bader, M. Y. (Maaike Y.), Bahalkeh, K. (Khadijeh), Barancok, P. (Peter), Barrio, I. C. (Isabel C.), Barros, A. (Agustina), Barthel, M. (Matti), Basham, E. W. (Edmund W.), Bauters, M. (Marijn), Bazzichetto, M. (Manuele), Marchesini, L. B. (Luca Belelli), Bell, M. C. (Michael C.), Benavides, J. C. (Juan C.), Benito Alonso, J. L. (Jose Luis), Berauer, B. J. (Bernd J.), Bjerke, J. W. (Jarle W.), Bjork, R. G. (Robert G.), Bjorkman, M. P. (Mats P.), Bjornsdottir, K. (Katrin), Blonder, B. (Benjamin), Boeckx, P. (Pascal), Boike, J. (Julia), Bokhorst, S. (Stef), Brum, B. N. (Barbara N. S.), Bruna, J. (Josef), Buchmann, N. (Nina), Buysse, P. (Pauline), Camargo, J. L. (Jose Luis), Campoe, O. C. (Otavio C.), Candan, O. (Onur), Canessa, R. (Rafaella), Cannone, N. (Nicoletta), Carbognani, M. (Michele), Carnicer, J. (Jofre), Casanova-Katny, A. (Angelica), Cesarz, S. (Simone), Chojnicki, B. (Bogdan), Choler, P. (Philippe), Chown, S. L. (Steven L.), Cifuentes, E. F. (Edgar F.), Ciliak, M. (Marek), Contador, T. (Tamara), Convey, P. (Peter), Cooper, E. J. (Elisabeth J.), Cremonese, E. (Edoardo), Curasi, S. R. (Salvatore R.), Curtis, R. (Robin), Cutini, M. (Maurizio), Dahlberg, C. J. (C. Johan), Daskalova, G. N. (Gergana N.), Angel de Pablo, M. (Miguel), Della Chiesa, S. (Stefano), Dengler, J. (Juergen), Deronde, B. (Bart), Descombes, P. (Patrice), Di Cecco, V. (Valter), Di Musciano, M. (Michele), Dick, J. (Jan), Dimarco, R. D. (Romina D.), Dolezal, J. (Jiri), Dorrepaal, E. (Ellen), Dusek, J. (Jiri), Eisenhauer, N. (Nico), Eklundh, L. (Lars), Erickson, T. E. (Todd E.), Erschbamer, B. (Brigitta), Eugster, W. (Werner), Ewers, R. M. (Robert M.), Exton, D. A. (Dan A.), Fanin, N. (Nicolas), Fazlioglu, F. (Fatih), Feigenwinter, I. (Iris), Fenu, G. (Giuseppe), Ferlian, O. (Olga), Fernandez Calzado, M. R. (M. Rosa), Fernandez-Pascual, E. (Eduardo), Finckh, M. (Manfred), Higgens, R. F. (Rebecca Finger), Forte, T. G. (T'ai G. W.), Freeman, E. C. (Erika C.), Frei, E. R. (Esther R.), Fuentes-Lillo, E. (Eduardo), Garcia, R. A. (Rafael A.), Garcia, M. B. (Maria B.), Geron, C. (Charly), Gharun, M. (Mana), Ghosn, D. (Dany), Gigauri, K. (Khatuna), Gobin, A. (Anne), Goded, I. (Ignacio), Goeckede, M. (Mathias), Gottschall, F. (Felix), Goulding, K. (Keith), Govaert, S. (Sanne), Graae, B. J. (Bente Jessen), Greenwood, S. (Sarah), Greiser, C. (Caroline), Grelle, A. (Achim), Guenard, B. (Benoit), Guglielmin, M. (Mauro), Guillemot, J. (Joannes), Haase, P. (Peter), Haider, S. (Sylvia), Halbritter, A. H. (Aud H.), Hamid, M. (Maroof), Hammerle, A. (Albin), Hampe, A. (Arndt), Haugum, S. V. (Siri, V), Hederova, L. (Lucia), Heinesch, B. (Bernard), Helfter, C. (Carole), Hepenstrick, D. (Daniel), Herberich, M. (Maximiliane), Herbst, M. (Mathias), Hermanutz, L. (Luise), Hik, D. S. (David S.), Hoffren, R. (Raul), Homeier, J. (Juergen), Hörtnagl, L. (Lukas), Hoye, T. T. (Toke T.), Hrbacek, F. (Filip), Hylander, K. (Kristoffer), Iwata, H. (Hiroki), Jackowicz-Korczynski, M. A. (Marcin Antoni), Jactel, H. (Herve), Jarveoja, J. (Jarvi), Jastrzebowski, S. (Szymon), Jentsch, A. (Anke), Jimenez, J. J. (Juan J.), Jonsdottir, I. S. (Ingibjorg S.), Jucker, T. (Tommaso), Jump, A. S. (Alistair S.), Juszczak, R. (Radoslaw), Kanka, R. (Robert), Kaspar, V. (Vit), Kazakis, G. (George), Kelly, J. (Julia), Khuroo, A. A. (Anzar A.), Klemedtsson, L. (Leif), Klisz, M. (Marcin), Kljun, N. (Natascha), Knohl, A. (Alexander), Kobler, J. (Johannes), Kollar, J. (Jozef), Kotowska, M. M. (Martyna M.), Kovacs, B. (Bence), Kreyling, J. (Juergen), Lamprecht, A. (Andrea), Lang, S. I. (Simone, I), Larson, C. (Christian), Larson, K. (Keith), Laska, K. (Kamil), Maire, G. I. (Guerric Ie), Leihy, R. I. (Rachel, I), Lens, L. (Luc), Liljebladh, B. (Bengt), Lohila, A. (Annalea), Lorite, J. (Juan), Loubet, B. (Benjamin), Lynn, J. (Joshua), Macek, M. (Martin), Mackenzie, R. (Roy), Magliulo, E. (Enzo), Maier, R. (Regine), Malfasi, F. (Francesco), Malis, F. (Frantisek), Man, M. (Matej), Manca, G. (Giovanni), Manco, A. (Antonio), Manise, T. (Tanguy), Manolaki, P. (Paraskevi), Marciniak, F. (Felipe), Matula, R. (Radim), Clara Mazzolari, A. (Ana), Medinets, S. (Sergiy), Medinets, V. (Volodymyr), Meeussen, C. (Camille), Merinero, S. (Sonia), Guimaraes Mesquita, R. d. (Rita de Cassia), Meusburger, K. (Katrin), Meysman, F. J. (Filip J. R.), Michaletz, S. T. (Sean T.), Milbau, A. (Ann), Moiseev, D. (Dmitry), Moiseev, P. (Pavel), Mondoni, A. (Andrea), Monfries, R. (Ruth), Montagnani, L. (Leonardo), Moriana-Armendariz, M. (Mikel), di Cella, U. M. (Umberto Morra), Moersdorf, M. (Martin), Mosedale, J. R. (Jonathan R.), Muffler, L. (Lena), Munoz-Rojas, M. (Miriam), Myers, J. A. (Jonathan A.), Myers-Smith, I. H. (Isla H.), Nagy, L. (Laszlo), Nardino, M. (Marianna), Naujokaitis-Lewis, I. (Ilona), Newling, E. (Emily), Nicklas, L. (Lena), Niedrist, G. (Georg), Niessner, A. (Armin), Nilsson, M. B. (Mats B.), Normand, S. (Signe), Nosetto, M. D. (Marcelo D.), Nouvellon, Y. (Yann), Nunez, M. A. (Martin A.), Ogaya, R. (Roma), Ogee, J. (Jerome), Okello, J. (Joseph), Olejnik, J. (Janusz), Olesen, J. E. (Jorgen Eivind), Opedal, O. H. (Oystein H.), Orsenigo, S. (Simone), Palaj, A. (Andrej), Pampuch, T. (Timo), Panov, A. V. (Alexey V.), Pärtel, M. (Meelis), Pastor, A. (Ada), Pauchard, A. (Aníbal), Pauli, H. (Harald), Pavelka, M. (Marian), Pearse, W. D. (William D.), Peichl, M. (Matthias), Pellissier, L. (Loïc), Penczykowski, R. M. (Rachel M.), Penuelas, J. (Josep), Petit Bon, M. (Matteo), Petraglia, A. (Alessandro), Phartyal, S. S. (Shyam S.), Phoenix, G. K. (Gareth K.), Pio, C. (Casimiro), Pitacco, A. (Andrea), Pitteloud, C. (Camille), Plichta, R. (Roman), Porro, F. (Francesco), Portillo-Estrada, M. (Miguel), Poulenard, J. (Jérôme), Poyatos, R. (Rafael), Prokushkin, A. S. (Anatoly S.), Puchalka, R. (Radoslaw), Pușcaș, M. (Mihai), Radujković, D. (Dajana), Randall, K. (Krystal), Ratier Backes, A. (Amanda), Remmele, S. (Sabine), Remmers, W. (Wolfram), Renault, D. (David), Risch, A. C. (Anita C.), Rixen, C. (Christian), Robinson, S. A. (Sharon A.), Robroek, B. J. (Bjorn J. M.), Rocha, A. V. (Adrian V.), Rossi, C. (Christian), Rossi, G. (Graziano), Roupsard, O. (Olivier), Rubtsov, A. V. (Alexey V.), Saccone, P. (Patrick), Sagot, C. (Clotilde), Sallo Bravo, J. (Jhonatan), Santos, C. C. (Cinthya C.), Sarneel, J. M. (Judith M.), Scharnweber, T. (Tobias), Schmeddes, J. (Jonas), Schmidt, M. (Marius), Scholten, T. (Thomas), Schuchardt, M. (Max), Schwartz, N. (Naomi), Scott, T. (Tony), Seeber, J. (Julia), Segalin De Andrade, A. C. (Ana Cristina), Seipel, T. (Tim), Semenchuk, P. (Philipp), Senior, R. A. (Rebecca A.), Serra-Diaz, J. M. (Josep M.), Sewerniak, P. (Piotr), Shekhar, A. (Ankit), Sidenko, N. V. (Nikita V.), Siebicke, L. (Lukas), Siegwart Collier, L. (Laura), Simpson, E. (Elizabeth), Siqueira, D. P. (David P.), Sitková, Z. (Zuzana), Six, J. (Johan), Smiljanic, M. (Marko), Smith, S. W. (Stuart W.), Smith-Tripp, S. (Sarah), Somers, B. (Ben), Sørensen, M. V. (Mia Vedel), Souza, J. J. (José João L. L.), Souza, B. I. (Bartolomeu Israel), Dias, A. S. (Arildo Souza), Spasojevic, M. J. (Marko J.), Speed, J. D. (James D. M.), Spicher, F. (Fabien), Stanisci, A. (Angela), Steinbauer, K. (Klaus), Steinbrecher, R. (Rainer), Steinwandter, M. (Michael), Stemkovski, M. (Michael), Stephan, J. G. (Jörg G.), Stiegler, C. (Christian), Stoll, S. (Stefan), Svátek, M. (Martin), Svoboda, M. (Miroslav), Tagesson, T. (Torbern), Tanentzap, A. J. (Andrew J.), Tanneberger, F. (Franziska), Theurillat, J.-P. (Jean-Paul), Thomas, H. J. (Haydn J. D.), Thomas, A. D. (Andrew D.), Tielbörger, K. (Katja), Tomaselli, M. (Marcello), Treier, U. A. (Urs Albert), Trouillier, M. (Mario), Turtureanu, P. D. (Pavel Dan), Tutton, R. (Rosamond), Tyystjärvi, V. A. (Vilna A.), Ueyama, M. (Masahito), Ujházy, K. (Karol), Ujházyová, M. (Mariana), Uogintas, D. (Domas), Urban, A. V. (Anastasiya V.), Urban, J. (Josef), Urbaniak, M. (Marek), Ursu, T.-M. (Tudor-Mihai), Vaccari, F. P. (Francesco Primo), Van De Vondel, S. (Stijn), Van Den Brink, L. (Liesbeth), Van Geel, M. (Maarten), Vandvik, V. (Vigdis), Vangansbeke, P. (Pieter), Varlagin, A. (Andrej), Veen, G. F. (G. F.), Veenendaal, E. (Elmar), Venn, S. E. (Susanna E.), Verbeeck, H. (Hans), Verbrugggen, E. (Erik), Verheijen, F. G. (Frank G. A.), Villar, L. (Luis), Vitale, L. (Luca), Vittoz, P. (Pascal), Vives-Ingla, M. (Maria), Von Oppen, J. (Jonathan), Walz, J. (Josefine), Wang, R. (Runxi), Wang, Y. (Yifeng), Way, R. G. (Robert G.), Wedegärtner, R. E. (Ronja E. M.), Weigel, R. (Robert), Wild, J. (Jan), Wilkinson, M. (Matthew), Wilmking, M. (Martin), Wingate, L. (Lisa), Winkler, M. (Manuela), Wipf, S. (Sonja), Wohlfahrt, G. (Georg), Xenakis, G. (Georgios), Yang, Y. (Yan), Yu, Z. (Zicheng), Yu, K. (Kailiang), Zellweger, F. (Florian), Zhang, J. (Jian), Zhang, Z. (Zhaochen), Zhao, P. (Peng), Ziemblińska, K. (Klaudia), Zimmermann, R. (Reiner), Zong, S. (Shengwei), Zyryanov, V. I. (Viacheslav I.), Nijs, I. (Ivan), Lenoir, J. (Jonathan), Lembrechts, J. J. (Jonas J.), van den Hoogen, J. (Johan), Aalto, J. (Juha), Ashcroft, M. B. (Michael B.), De Frenne, P. (Pieter), Kemppinen, J. (Julia), Kopecky, M. (Martin), Luoto, M. (Miska), Maclean, I. M. (Ilya M. D.), Crowther, T. W. (Thomas W.), Bailey, J. J. (Joseph J.), Haesen, S. (Stef), Klinges, D. H. (David H.), Niittynen, P. (Pekka), Scheffers, B. R. (Brett R.), Van Meerbeek, K. (Koenraad), Aartsma, P. (Peter), Abdalaze, O. (Otar), Abedi, M. (Mehdi), Aerts, R. (Rien), Ahmadian, N. (Negar), Ahrends, A. (Antje), Alatalo, J. M. (Juha M.), Alexander, J. M. (Jake M.), Allonsius, C. N. (Camille Nina), Altman, J. (Jan), Ammann, C. (Christof), Andres, C. (Christian), Andrews, C. (Christopher), Ardo, J. (Jonas), Arriga, N. (Nicola), Arzac, A. (Alberto), Aschero, V. (Valeria), Assis, R. L. (Rafael L.), Assmann, J. J. (Jakob Johann), Bader, M. Y. (Maaike Y.), Bahalkeh, K. (Khadijeh), Barancok, P. (Peter), Barrio, I. C. (Isabel C.), Barros, A. (Agustina), Barthel, M. (Matti), Basham, E. W. (Edmund W.), Bauters, M. (Marijn), Bazzichetto, M. (Manuele), Marchesini, L. B. (Luca Belelli), Bell, M. C. (Michael C.), Benavides, J. C. (Juan C.), Benito Alonso, J. L. (Jose Luis), Berauer, B. J. (Bernd J.), Bjerke, J. W. (Jarle W.), Bjork, R. G. (Robert G.), Bjorkman, M. P. (Mats P.), Bjornsdottir, K. (Katrin), Blonder, B. (Benjamin), Boeckx, P. (Pascal), Boike, J. (Julia), Bokhorst, S. (Stef), Brum, B. N. (Barbara N. S.), Bruna, J. (Josef), Buchmann, N. (Nina), Buysse, P. (Pauline), Camargo, J. L. (Jose Luis), Campoe, O. C. (Otavio C.), Candan, O. (Onur), Canessa, R. (Rafaella), Cannone, N. (Nicoletta), Carbognani, M. (Michele), Carnicer, J. (Jofre), Casanova-Katny, A. (Angelica), Cesarz, S. (Simone), Chojnicki, B. (Bogdan), Choler, P. (Philippe), Chown, S. L. (Steven L.), Cifuentes, E. F. (Edgar F.), Ciliak, M. (Marek), Contador, T. (Tamara), Convey, P. (Peter), Cooper, E. J. (Elisabeth J.), Cremonese, E. (Edoardo), Curasi, S. R. (Salvatore R.), Curtis, R. (Robin), Cutini, M. (Maurizio), Dahlberg, C. J. (C. Johan), Daskalova, G. N. (Gergana N.), Angel de Pablo, M. (Miguel), Della Chiesa, S. (Stefano), Dengler, J. (Juergen), Deronde, B. (Bart), Descombes, P. (Patrice), Di Cecco, V. (Valter), Di Musciano, M. (Michele), Dick, J. (Jan), Dimarco, R. D. (Romina D.), Dolezal, J. (Jiri), Dorrepaal, E. (Ellen), Dusek, J. (Jiri), Eisenhauer, N. (Nico), Eklundh, L. (Lars), Erickson, T. E. (Todd E.), Erschbamer, B. (Brigitta), Eugster, W. (Werner), Ewers, R. M. (Robert M.), Exton, D. A. (Dan A.), Fanin, N. (Nicolas), Fazlioglu, F. (Fatih), Feigenwinter, I. (Iris), Fenu, G. (Giuseppe), Ferlian, O. (Olga), Fernandez Calzado, M. R. (M. Rosa), Fernandez-Pascual, E. (Eduardo), Finckh, M. (Manfred), Higgens, R. F. (Rebecca Finger), Forte, T. G. (T'ai G. W.), Freeman, E. C. (Erika C.), Frei, E. R. (Esther R.), Fuentes-Lillo, E. (Eduardo), Garcia, R. A. (Rafael A.), Garcia, M. B. (Maria B.), Geron, C. (Charly), Gharun, M. (Mana), Ghosn, D. (Dany), Gigauri, K. (Khatuna), Gobin, A. (Anne), Goded, I. (Ignacio), Goeckede, M. (Mathias), Gottschall, F. (Felix), Goulding, K. (Keith), Govaert, S. (Sanne), Graae, B. J. (Bente Jessen), Greenwood, S. (Sarah), Greiser, C. (Caroline), Grelle, A. (Achim), Guenard, B. (Benoit), Guglielmin, M. (Mauro), Guillemot, J. (Joannes), Haase, P. (Peter), Haider, S. (Sylvia), Halbritter, A. H. (Aud H.), Hamid, M. (Maroof), Hammerle, A. (Albin), Hampe, A. (Arndt), Haugum, S. V. (Siri, V), Hederova, L. (Lucia), Heinesch, B. (Bernard), Helfter, C. (Carole), Hepenstrick, D. (Daniel), Herberich, M. (Maximiliane), Herbst, M. (Mathias), Hermanutz, L. (Luise), Hik, D. S. (David S.), Hoffren, R. (Raul), Homeier, J. (Juergen), Hörtnagl, L. (Lukas), Hoye, T. T. (Toke T.), Hrbacek, F. (Filip), Hylander, K. (Kristoffer), Iwata, H. (Hiroki), Jackowicz-Korczynski, M. A. (Marcin Antoni), Jactel, H. (Herve), Jarveoja, J. (Jarvi), Jastrzebowski, S. (Szymon), Jentsch, A. (Anke), Jimenez, J. J. (Juan J.), Jonsdottir, I. S. (Ingibjorg S.), Jucker, T. (Tommaso), Jump, A. S. (Alistair S.), Juszczak, R. (Radoslaw), Kanka, R. (Robert), Kaspar, V. (Vit), Kazakis, G. (George), Kelly, J. (Julia), Khuroo, A. A. (Anzar A.), Klemedtsson, L. (Leif), Klisz, M. (Marcin), Kljun, N. (Natascha), Knohl, A. (Alexander), Kobler, J. (Johannes), Kollar, J. (Jozef), Kotowska, M. M. (Martyna M.), Kovacs, B. (Bence), Kreyling, J. (Juergen), Lamprecht, A. (Andrea), Lang, S. I. (Simone, I), Larson, C. (Christian), Larson, K. (Keith), Laska, K. (Kamil), Maire, G. I. (Guerric Ie), Leihy, R. I. (Rachel, I), Lens, L. (Luc), Liljebladh, B. (Bengt), Lohila, A. (Annalea), Lorite, J. (Juan), Loubet, B. (Benjamin), Lynn, J. (Joshua), Macek, M. (Martin), Mackenzie, R. (Roy), Magliulo, E. (Enzo), Maier, R. (Regine), Malfasi, F. (Francesco), Malis, F. (Frantisek), Man, M. (Matej), Manca, G. (Giovanni), Manco, A. (Antonio), Manise, T. (Tanguy), Manolaki, P. (Paraskevi), Marciniak, F. (Felipe), Matula, R. (Radim), Clara Mazzolari, A. (Ana), Medinets, S. (Sergiy), Medinets, V. (Volodymyr), Meeussen, C. (Camille), Merinero, S. (Sonia), Guimaraes Mesquita, R. d. (Rita de Cassia), Meusburger, K. (Katrin), Meysman, F. J. (Filip J. R.), Michaletz, S. T. (Sean T.), Milbau, A. (Ann), Moiseev, D. (Dmitry), Moiseev, P. (Pavel), Mondoni, A. (Andrea), Monfries, R. (Ruth), Montagnani, L. (Leonardo), Moriana-Armendariz, M. (Mikel), di Cella, U. M. (Umberto Morra), Moersdorf, M. (Martin), Mosedale, J. R. (Jonathan R.), Muffler, L. (Lena), Munoz-Rojas, M. (Miriam), Myers, J. A. (Jonathan A.), Myers-Smith, I. H. (Isla H.), Nagy, L. (Laszlo), Nardino, M. (Marianna), Naujokaitis-Lewis, I. (Ilona), Newling, E. (Emily), Nicklas, L. (Lena), Niedrist, G. (Georg), Niessner, A. (Armin), Nilsson, M. B. (Mats B.), Normand, S. (Signe), Nosetto, M. D. (Marcelo D.), Nouvellon, Y. (Yann), Nunez, M. A. (Martin A.), Ogaya, R. (Roma), Ogee, J. (Jerome), Okello, J. (Joseph), Olejnik, J. (Janusz), Olesen, J. E. (Jorgen Eivind), Opedal, O. H. (Oystein H.), Orsenigo, S. (Simone), Palaj, A. (Andrej), Pampuch, T. (Timo), Panov, A. V. (Alexey V.), Pärtel, M. (Meelis), Pastor, A. (Ada), Pauchard, A. (Aníbal), Pauli, H. (Harald), Pavelka, M. (Marian), Pearse, W. D. (William D.), Peichl, M. (Matthias), Pellissier, L. (Loïc), Penczykowski, R. M. (Rachel M.), Penuelas, J. (Josep), Petit Bon, M. (Matteo), Petraglia, A. (Alessandro), Phartyal, S. S. (Shyam S.), Phoenix, G. K. (Gareth K.), Pio, C. (Casimiro), Pitacco, A. (Andrea), Pitteloud, C. (Camille), Plichta, R. (Roman), Porro, F. (Francesco), Portillo-Estrada, M. (Miguel), Poulenard, J. (Jérôme), Poyatos, R. (Rafael), Prokushkin, A. S. (Anatoly S.), Puchalka, R. (Radoslaw), Pușcaș, M. (Mihai), Radujković, D. (Dajana), Randall, K. (Krystal), Ratier Backes, A. (Amanda), Remmele, S. (Sabine), Remmers, W. (Wolfram), Renault, D. (David), Risch, A. C. (Anita C.), Rixen, C. (Christian), Robinson, S. A. (Sharon A.), Robroek, B. J. (Bjorn J. M.), Rocha, A. V. (Adrian V.), Rossi, C. (Christian), Rossi, G. (Graziano), Roupsard, O. (Olivier), Rubtsov, A. V. (Alexey V.), Saccone, P. (Patrick), Sagot, C. (Clotilde), Sallo Bravo, J. (Jhonatan), Santos, C. C. (Cinthya C.), Sarneel, J. M. (Judith M.), Scharnweber, T. (Tobias), Schmeddes, J. (Jonas), Schmidt, M. (Marius), Scholten, T. (Thomas), Schuchardt, M. (Max), Schwartz, N. (Naomi), Scott, T. (Tony), Seeber, J. (Julia), Segalin De Andrade, A. C. (Ana Cristina), Seipel, T. (Tim), Semenchuk, P. (Philipp), Senior, R. A. (Rebecca A.), Serra-Diaz, J. M. (Josep M.), Sewerniak, P. (Piotr), Shekhar, A. (Ankit), Sidenko, N. V. (Nikita V.), Siebicke, L. (Lukas), Siegwart Collier, L. (Laura), Simpson, E. (Elizabeth), Siqueira, D. P. (David P.), Sitková, Z. (Zuzana), Six, J. (Johan), Smiljanic, M. (Marko), Smith, S. W. (Stuart W.), Smith-Tripp, S. (Sarah), Somers, B. (Ben), Sørensen, M. V. (Mia Vedel), Souza, J. J. (José João L. L.), Souza, B. I. (Bartolomeu Israel), Dias, A. S. (Arildo Souza), Spasojevic, M. J. (Marko J.), Speed, J. D. (James D. M.), Spicher, F. (Fabien), Stanisci, A. (Angela), Steinbauer, K. (Klaus), Steinbrecher, R. (Rainer), Steinwandter, M. (Michael), Stemkovski, M. (Michael), Stephan, J. G. (Jörg G.), Stiegler, C. (Christian), Stoll, S. (Stefan), Svátek, M. (Martin), Svoboda, M. (Miroslav), Tagesson, T. (Torbern), Tanentzap, A. J. (Andrew J.), Tanneberger, F. (Franziska), Theurillat, J.-P. (Jean-Paul), Thomas, H. J. (Haydn J. D.), Thomas, A. D. (Andrew D.), Tielbörger, K. (Katja), Tomaselli, M. (Marcello), Treier, U. A. (Urs Albert), Trouillier, M. (Mario), Turtureanu, P. D. (Pavel Dan), Tutton, R. (Rosamond), Tyystjärvi, V. A. (Vilna A.), Ueyama, M. (Masahito), Ujházy, K. (Karol), Ujházyová, M. (Mariana), Uogintas, D. (Domas), Urban, A. V. (Anastasiya V.), Urban, J. (Josef), Urbaniak, M. (Marek), Ursu, T.-M. (Tudor-Mihai), Vaccari, F. P. (Francesco Primo), Van De Vondel, S. (Stijn), Van Den Brink, L. (Liesbeth), Van Geel, M. (Maarten), Vandvik, V. (Vigdis), Vangansbeke, P. (Pieter), Varlagin, A. (Andrej), Veen, G. F. (G. F.), Veenendaal, E. (Elmar), Venn, S. E. (Susanna E.), Verbeeck, H. (Hans), Verbrugggen, E. (Erik), Verheijen, F. G. (Frank G. A.), Villar, L. (Luis), Vitale, L. (Luca), Vittoz, P. (Pascal), Vives-Ingla, M. (Maria), Von Oppen, J. (Jonathan), Walz, J. (Josefine), Wang, R. (Runxi), Wang, Y. (Yifeng), Way, R. G. (Robert G.), Wedegärtner, R. E. (Ronja E. M.), Weigel, R. (Robert), Wild, J. (Jan), Wilkinson, M. (Matthew), Wilmking, M. (Martin), Wingate, L. (Lisa), Winkler, M. (Manuela), Wipf, S. (Sonja), Wohlfahrt, G. (Georg), Xenakis, G. (Georgios), Yang, Y. (Yan), Yu, Z. (Zicheng), Yu, K. (Kailiang), Zellweger, F. (Florian), Zhang, J. (Jian), Zhang, Z. (Zhaochen), Zhao, P. (Peng), Ziemblińska, K. (Klaudia), Zimmermann, R. (Reiner), Zong, S. (Shengwei), Zyryanov, V. I. (Viacheslav I.), Nijs, I. (Ivan), and Lenoir, J. (Jonathan)

Abstract

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0‐5 and 5‐15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1‐km² pixels (summarized from 8519 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10° degrees C (mean = 3.0 +/‐ 2.1° degrees C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 +/‐2.3° degrees C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (‐0.7 +/‐ 2.3° degrees C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological

Published
2022

5. Europe-wide reduction in primary productivity caused by the heat and drought in 2003

Author

Ciais, Ph., Reichstein, M., Viovy, N., Granier, A., Ogee, J., Allard, V., Aubinet, M., Buchmann, N., Bernhofer, Chr., Carrara, A., Chevallier, F., De Noblet, N., Friend, A. D., Friedlingstein, P., Grunwald, T., Heinesch, B., Keronen, P., Knohl, A., Krinner, G., Loustau, D., Manca, G., Matteucci, G., Miglietta, F., Ourcival, J. M., Papale, D., Pilegaard, K., Rambal, S., Seufert, G., Soussana, J. F., Sanz, M. J., Schulze, E. D., Vesala, T., and Valentini, R.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Ph. Ciais (corresponding author) [1]; M. Reichstein [2, 3]; N. Viovy [1]; A. Granier [4]; J. Ogée [5]; V. Allard [6]; M. Aubinet [7]; N. Buchmann [8]; Chr. Bernhofer [...]

Published
2005
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6. Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest

Author

Barbeta, A., Jones, S.P., Clavé, L., Wingate, L., Gimeno, T.E., Fréjaville, B., Wohl, S., Ogee, J., Barbeta, A., Jones, S.P., Clavé, L., Wingate, L., Gimeno, T.E., Fréjaville, B., Wohl, S., and Ogee, J.

Abstract

We investigated plant water sources of an emblematic refugial population of Fagus sylvatica (L.) in the Ciron river gorges in south-western France using stable water isotopes. It is generally assumed that no isotopic fractionation occurs during root water uptake, so that the isotopic composition of xylem water effectively reflects that of source water. However, this assumption has been called into question by recent studies that found that, at least at some dates during the growing season, plant water did not reflect any mixture of the potential water sources. In this context, highly resolved datasets covering a range of environmental conditions could shed light on possible plant soil fractionation processes responsible for this phenomenon. In this study, the hydrogen (2H) and oxygen (18O) isotope compositions of all potential tree water sources and xylem water were measured fortnightly over an entire growing season. Using a Bayesian isotope mixing model (MixSIAR), we then quantified the relative contribution of water sources for F. sylvatica and Quercus robur (L.) trees. Based on 18O data alone, both species used a mix of top and deep soil water over the season, with Q. robur using deeper soil water than F. sylvatica. The contribution of stream water appeared to be marginal despite the proximity of the trees to the stream, as already reported for other riparian forests. Xylem water 18O could always be interpreted as a mixture of deep and shallow soil waters, but the 2H of xylem water was often more depleted than the considered water sources. We argue that an isotopic fractionation in the unsaturated zone and/or within the plant tissues could underlie this unexpected relatively depleted 2H of xylem water, as already observed in halophytic and xerophytic species. By means of a sensitivity analysis, we found that the estimation of plant water sources using mixing models was strongly affected by this 2H depletion. A better understanding of what causes this isotopic sep

Published
2019

8. Multi-scale predictions of massive conifer mortality due to chronic temperature rise (vol 6, pg 295, 2016)

Author

McDowell, NG, McDowell, NG, Williams, AP, Xu, C, Pockman, WT, Dickman, LT, Sevanto, S, Pangle, R, Limousin, J, Plaut, J, Mackay, DS, Ogee, J, Domec, JC, Allen, CD, Fisher, RA, Jiang, X, Muss, JD, Breshears, DD, Rauscher, SA, Koven, C, McDowell, NG, McDowell, NG, Williams, AP, Xu, C, Pockman, WT, Dickman, LT, Sevanto, S, Pangle, R, Limousin, J, Plaut, J, Mackay, DS, Ogee, J, Domec, JC, Allen, CD, Fisher, RA, Jiang, X, Muss, JD, Breshears, DD, Rauscher, SA, and Koven, C

Published
2016

9. Interpreting canopy development and physiology using a European phenology camera network at flux sites

Author

Wingate, L., Ogee, J., Cremonese, E., Filippa, G., Mizunuma, T., Migliavacca, M., Moisy, C., Wilkinson, M., Moureaux, C., Wohlfahrt, G., Hammerle, A., Hoertnagl, L., Gimeno, C., Porcar-Castell, A., Galvagno, M., Nakaji, T., Morison, J., Kolle, O., Knohl, A., Kutsch, W., Kolari, P., Nikinmaa, E., Ibrom, A., Gielen, B., Eugster, W., Balzarolo, M., Papale, D., Klumpp, K., Koestner, B., Gruenwald, T., Joffre, R., Ourcival, J. -M., Hellstrom, M., Lindroth, A., George, C., Longdoz, B., Genty, B., Levula, J., Heinesch, B., Sprintsin, M., Yakir, D., Manise, T., Guyon, D., Ahrends, H., Plaza-Aguilar, A., Guan, J. H., Grace, J., Wingate, L., Ogee, J., Cremonese, E., Filippa, G., Mizunuma, T., Migliavacca, M., Moisy, C., Wilkinson, M., Moureaux, C., Wohlfahrt, G., Hammerle, A., Hoertnagl, L., Gimeno, C., Porcar-Castell, A., Galvagno, M., Nakaji, T., Morison, J., Kolle, O., Knohl, A., Kutsch, W., Kolari, P., Nikinmaa, E., Ibrom, A., Gielen, B., Eugster, W., Balzarolo, M., Papale, D., Klumpp, K., Koestner, B., Gruenwald, T., Joffre, R., Ourcival, J. -M., Hellstrom, M., Lindroth, A., George, C., Longdoz, B., Genty, B., Levula, J., Heinesch, B., Sprintsin, M., Yakir, D., Manise, T., Guyon, D., Ahrends, H., Plaza-Aguilar, A., Guan, J. H., and Grace, J.

Abstract

Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and their response to climate and management practices are crudely represented in land surface models. As visual observations of phenology are laborious, there is a need to supplement long-term observations with automated techniques such as those provided by digital repeat photography at high temporal and spatial resolution. We present the first synthesis from a growing observational network of digital cameras installed on towers across Europe above deciduous and evergreen forests, grasslands and croplands, where vegetation and atmosphere CO2 fluxes are measured continuously. Using colour indices from digital images and using piecewise regression analysis of time series, we explored whether key changes in canopy phenology could be detected automatically across different land use types in the network. The piecewise regression approach could capture the start and end of the growing season, in addition to identifying striking changes in colour signals caused by flowering and management practices such as mowing. Exploring the dates of green-up and senescence of deciduous forests extracted by the piecewise regression approach against dates estimated from visual observations, we found that these phenological events could be detected adequately (RMSE < 8 and 11 days for leaf out and leaf fall, respectively). We also investigated whether the seasonal patterns of red, green and blue colour fractions derived from digital images could be modelled mechanistically using the PROSAIL model parameterised with information of seasonal changes in canopy leaf area and leaf chlorophyll and carotenoid concentrations. From a model sensitivity analysis we found that variations in colour fractions, and in particular the late spring 'green hump' observed repeatedly in deciduous broadleaf canopies ac

Published
2015

10. Multi-scale predictions of massive conifer mortality due to chronic temperature rise

Author

McDowell, N. G., primary, Williams, A. P., additional, Xu, C., additional, Pockman, W. T., additional, Dickman, L. T., additional, Sevanto, S., additional, Pangle, R., additional, Limousin, J., additional, Plaut, J., additional, Mackay, D. S., additional, Ogee, J., additional, Domec, J. C., additional, Allen, C. D., additional, Fisher, R. A., additional, Jiang, X., additional, Muss, J. D., additional, Breshears, D. D., additional, Rauscher, S. A., additional, and Koven, C., additional

Published
2015
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11. Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species: a historical delta C-13 and delta O-18 approach using herbarium samples

Author

Bonal, D., Ponton, S., Le Thiec, D., Richard, B., Ningre, N., Herault, B., Ogee, J., Gonzalez, S., Pignal, M., Sabatier, Daniel, and Guehl, J. M.

Subjects
tropical rainforests, carbon isotope composition, photosynthesis, fungi, stomata, food and beverages, environmental change, isotope composition, oxygen, herbarium
Abstract

We assessed the extent of recent environmental changes on leaf morphological (stomatal density, stomatal surface, leaf mass per unit area) and physiological traits (carbon isotope composition, delta C-13(leaf), and discrimination, Delta C-13(leaf), oxygen isotope composition, delta O-18(leaf)) of two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera) that are abundant in the Guiana shield (Northern Amazonia). Leaf samples were collected in different international herbariums to cover a 200 year time-period (1790-2004) and the whole Guiana shield. Using models describing carbon and oxygen isotope fractionations during photosynthesis, different scenarios of change in intercellular CO2 concentrations inside the leaf (C-i), stomatal conductance (g), and photosynthesis (A) were tested in order to understand leaf physiological response to increasing air CO2 concentrations (C-a). Our results confirmed that both species displayed physiological response to changing C-a. For both species, we observed a decrease of about 1.7% in delta C-13(leaf) since 1950, without significant change in Delta C-13(leaf) and leaf morphological traits. Furthermore, there was no clear change in delta O-18(leaf) for Humiria over this period. Our simulation approach revealed that an increase in A, rather than a decrease in g, explained the observed trends for these tropical rainforest species, allowing them to maintain a constant ratio of C-i/C-a.

Published
2011

13. The impact of soil microorganisms on the global budget of delta O-18 in atmospheric CO2

Author

Peylin, Philippe, Wingate, L., Ogee, J., Cuntz, M., Genty, Bernard, Reiter, I., Maseyk, K., Seibt, Uli, Yakir, D., Pendall, E., Barbour, Mm, Mortazavi, B., Burlett, R., Miller, J., Mencuccini, M., Shim, Jh, Hunt, J., Grace, J., Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Biologie cellulaire et moléculaire des plantes et des bactéries (BCMPB), Université de la Méditerranée - Aix-Marseille 2-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Department Environmental Science and Energy Research, Department of Botany, University of Wyoming (UW), Florida State University [Tallahassee] (FSU), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Institute of Ecology and Resource Management, and University of Edinburgh

Abstract

International audience; Improved global estimates of terrestrial photosynthesis and respiration are critical for predicting the rate of change in atmospheric CO2. The oxygen isotopic composition of atmospheric CO2 can be used to estimate these fluxes because oxygen isotopic exchange between CO2 and water creates distinct isotopic flux signatures. The enzyme carbonic anhydrase (CA) is known to accelerate this exchange in leaves, but the possibility of CA activity in soils is commonly neglected. Here, we report widespread accelerated soil CO2 hydration. Exchange was 10-300 times faster than the un-catalyzed rate, consistent with typical population sizes for CA-containing soil microorganisms. Including accelerated soil hydration in global model simulations modifies contributions from soil and foliage to the global (COO)-O-18 budget and eliminates persistent discrepancies existing between model and atmospheric observations. This enhanced soil hydration also increases the differences between the isotopic signatures of photosynthesis and respiration, particularly in the tropics, increasing the precision of CO2 gross fluxes obtained by using the delta O-18 of atmospheric CO2 by 50%.

Published
2009

14. Partitioning net ecosystem carbon exchange into net assimilation and respiration with canopy-scale isotopic measurements: An error propagation analysis with (CO2)-C-13 and (COO)-O-18 data

Author

Peylin, Philippe, Ogee, J., Cuntz, M., Bariac, T., Brunet, Y., Berbigier, P., Richard, Patrick, Ciais, P., Biogéochimie et écologie des milieux continentaux (Bioemco), and Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris)

Subjects
carbon 13, [SDE.MCG]Environmental Sciences/Global Changes, carbon cycle, oxygen 18, CO2 assimilation, respiration
Abstract

International audience; Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of nonfoliar respiration (F-R) and net photosynthesis (F-A) in order to better understand the variations of this exchange. However, the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes, and a rigorous estimation of the errors on F-A and F-R is needed. In this study, we account for and propagate uncertainties on all terms in the mass balance and isotopic mass balance equations for CO2 in order to get accurate estimates of the errors on F-A and F-R. We apply our method to a maritime pine forest in the southwest of France. Nighttime Keeling plots are used to estimate the C-13 and O-18 isotopic signature of F-R (delta(R)), and for both isotopes the a priori uncertainty associated with this term is estimated to be around 2% at our site. Using delta(13) C-CO2 and [CO2] measurements, we then show that the uncertainty on instantaneous values of F-A and F-R can be as large as 4 mumol m(-2) s(-1). Even if we could get more accurate estimates of the net CO2 flux, the isoflux, and the isotopic signatures of F-A and F-R, this uncertainty would not be significantly reduced because the isotopic disequilibrium between F-A and F-R is too small, around 2-3%. With delta(18)O-CO2 and [CO2] measurements the uncertainty associated with the gross fluxes lies also around 4 mumol m(-2) s(-1) but could be dramatically reduced if we were able to get more accurate estimates of the (COO)-O-18 isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between F-A and F-R is large, of the order of 12-17%. The isotopic disequilibrium between F-A and F-R and the uncertainty on delta(R) vary among ecosystems and over the year. Our approach should help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.

Published
2004

15. Modelling advection and diffusion of water isotopologues in leaves

Author

Cuntz, M., Ogee, J., Farquar, G. D., Peylin, P., Cernusak, Lucas A., Cuntz, M., Ogee, J., Farquar, G. D., Peylin, P., and Cernusak, Lucas A.

Abstract

We described advection and diffusion of water isotopologues in leaves in the non-steady state, applied specifically to amphistomatous leaves. This explains the isotopic enrichment of leaf water from the xylem to the mesophyll, and we showed how it relates to earlier models of leaf water enrichment in non-steady state. The effective length or tortuosity factor of isotopologue movement in leaves is unknown and, therefore, is a fitted parameter in the model. We compared the advection-diffusion model to previously published data sets for Lupinus angustifolius and Eucalyptus globulus. Night-time stomatal conductance was not measured in either data set and is therefore another fitted parameter. The model compared very well with the observations of bulk mesophyll water during the whole diel cycle. It compared well with the enrichment at the evaporative sites during the day but showed some deviations at night for E. globulus. It became clear from our analysis that night-time stomatal conductance should be measured in the future and that the temperature dependence of the tracer diffusivities should be accounted for. However, varying mesophyll water volume did not seem critical for obtaining a good prediction of leaf water enrichment, at least in our data sets. In addition, observations of single diurnal cycles do not seem to constrain the effective length that relates to the tortuosity of the water path in the mesophyll. Finally, we showed when simpler models of leaf water enrichment were suitable for applications of leaf water isotopes once weighted with the appropriate gas exchange flux. We showed that taking an unsuitable leaf water enrichment model could lead to large biases when cumulated over only 1 day.

Published
2007

17. Modeling climate change effects on the potential production of French plains forests at the sub-regional level

Author

Loustau, D., primary, Bosc, A., additional, Colin, A., additional, Ogee, J., additional, Davi, H., additional, Francois, C., additional, Dufrene, E., additional, Deque, M., additional, Cloppet, E., additional, Arrouays, D., additional, Le Bas, C., additional, Saby, N., additional, Pignard, G., additional, Hamza, N., additional, Granier, A., additional, Breda, N., additional, Ciais, P., additional, Viovy, N., additional, and Delage, F., additional

Published
2005
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18. Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks.

Author

Tramontana G, Migliavacca M, Jung M, Reichstein M, Keenan TF, Camps-Valls G, Ogee J, Verrelst J, and Papale D

Subjects
Carbon Cycle, Neural Networks, Computer, Photosynthesis, Respiration, Seasons, Carbon Dioxide, Ecosystem
Abstract

The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO 2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO 2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO 2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co-acting factors that modulate GPP and RECO flux dynamics. To overcome this limitation, we developed a hybrid data-driven approach based on combined neural networks (NN C-part ). NN C-part incorporates process knowledge by introducing a photosynthetic response based on the light-use efficiency (LUE) concept, and uses a comprehensive dataset of soil and micrometeorological variables as fluxes drivers. We applied the method to 36 sites from the FLUXNET2015 dataset and found a high consistency in the results with those derived from other standard partitioning methods for both GPP (R 2  > .94) and RECO (R 2  > .8). High consistency was also found for (a) the diurnal and seasonal patterns of fluxes and (b) the ecosystem functional responses. NN C-part performed more realistic than the traditional methods for predicting additional patterns of gross CO 2 fluxes, such as: (a) the GPP response to VPD, (b) direct effects of air temperature on GPP dynamics, (c) hysteresis in the diel cycle of gross CO 2 fluxes, (d) the sensitivity of LUE to the diffuse to direct radiation ratio, and (e) the post rain respiration pulse after a long dry period. In conclusion, NN C-part is a valid data-driven approach to provide GPP and RECO estimates and complementary to the existing partitioning methods., (© 2020 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

Published
2020
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19. Carbon stable isotope ratio of phloem sugars in mature pine trees throughout the growing season: comparison of two extraction methods.

Author

Devaux M, Ghashghaie J, Bert D, Lambrot C, Gessler A, Bathellier C, Ogee J, and Loustau D

Subjects
Pinus growth & development, Plant Extracts analysis, Seasons, Carbohydrates analysis, Carbon Isotopes analysis, Centrifugation methods, Chemical Fractionation methods, Phloem chemistry, Pinus chemistry
Abstract

The study presents a comparison of two phloem sugar extraction methods. The amount of phloem sugar extracted and the carbon isotope composition (delta(13)C) of the total extracts and of the main phloem compounds separated by high-performance liquid chromatography (sucrose, glucose, fructose and pinitol) are compared. These two phloem sap extraction methods are exudation in distilled water and a new method using centrifugation, which avoids the addition of any solvent. We applied both extraction methods on phloem discs sampled from 38-year-old Pinus pinaster trees in south-western France throughout the period from June 2007 to December 2008 on different time-scales: hourly, daily and monthly. We found that the centrifugation method systematically extracted ca. 50% less compounds from the phloem discs than the exudation method. In addition, the two extraction methods provided similar delta(13)C values of the total extracts, but the values obtained by the exudation method were 0.6 per thousand more negative than those calculated from the mass balance using the individual constituents. Over the growing season, both extraction methods exhibited lower total sugar content and more (13)C-enriched phloem sap in summer compared with winter values. These findings suggest that both extraction methods can be applied to study the carbon isotope composition of phloem sap, and the centrifugation method has the advantage that no solvent has to be added. The exudation method, however, is more appropriate for the quantification of the amounts of phloem sugars., (2009 John Wiley & Sons, Ltd.)

Published
2009
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20. Comparing and evaluating process-based ecosystem model predictions of carbon and water fluxes in major European forest biomes.

Author

Morales P, Sykes MT, Prentice IC, Smith P, Smith B, Bugmann H, Zierl B, Friedlingstein P, Viovy N, Sabaté S, Sánchez A, Pla E, Gracia CA, Sitch S, Arneth A, and Ogee J

Abstract

Process-based models can be classified into: (a) terrestrial biogeochemical models (TBMs), which simulate fluxes of carbon, water and nitrogen coupled within terrestrial ecosystems, and (b) dynamic global vegetation models (DGVMs), which further couple these processes interactively with changes in slow ecosystem processes depending on resource competition, establishment, growth and mortality of different vegetation types. In this study, four models - RHESSys, GOTILWA+, LPJ-GUESS and ORCHIDEE - representing both modelling approaches were compared and evaluated against benchmarks provided by eddy-covariance measurements of carbon and water fluxes at 15 forest sites within the EUROFLUX project. Overall, model-measurement agreement varied greatly among sites. Both modelling approaches have somewhat different strengths, but there was no model among those tested that universally performed well on the two variables evaluated. Small biases and errors suggest that ORCHIDEE and GOTILWA+ performed better in simulating carbon fluxes while LPJ-GUESS and RHESSys did a better job in simulating water fluxes. In general, the models can be considered as useful tools for studies of climate change impacts on carbon and water cycling in forests. However, the various sources of variation among models simulations and between models simulations and observed data described in this study place some constraints on the results and to some extent reduce their reliability. For example, at most sites in the Mediterranean region all models generally performed poorly most likely because of problems in the representation of water stress effects on both carbon uptake by photosynthesis and carbon release by heterotrophic respiration (R h ). The use of flux data as a means of assessing key processes in models of this type is an important approach to improving model performance. Our results show that the models have value but that further model development is necessary with regard to the representation of the some of the key ecosystem processes.

Published
2005
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