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3. The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Author

Salomón, Roberto L., Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G. W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bas J. W., Lindner, Marcus, Martinez-Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert-Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Ľubica, Dolezal, Jiri, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans-Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inken, Rathgeber, Cyrille B. K., Salmon, Yann, Saunders, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stojanović, Marko, Střelcová, Katarína, Světlík, Jan, Svoboda, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, and Steppe, Kathy

Published
2022
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7. The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Author

Salomón, Roberto Luis, Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G. W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bas J. W., Lindner, Marcus, Martínez Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert-Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Ľubica, Dolezal, Jiri, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans-Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inken, Rathgeber, Cyrille B. K., Salmon, Yann, Saunders, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stojanović, Marko, Střelcová, Katarína, Světlík, Jan, Svoboda, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, Steppe, Kathy, Salomón, Roberto Luis, Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G. W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bas J. W., Lindner, Marcus, Martínez Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert-Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Ľubica, Dolezal, Jiri, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans-Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inken, Rathgeber, Cyrille B. K., Salmon, Yann, Saunders, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stojanović, Marko, Střelcová, Katarína, Světlík, Jan, Svoboda, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, and Steppe, Kathy

Abstract

Altres ajuts: This work utilised the network of dendrometer observations established by the COST Action network STReESS (grant FP1106), Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.

Published
2022

8. The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Author

Ministerio de Ciencia e Innovación (España), Swiss National Science Foundation, Ministerio de Economía y Competitividad (España), Salomón, Roberto L., Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G.W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bass J.W., Lindner, Marcus, Martínez-Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert-Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Lubica, Doležal, Jiří, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans-Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inke, Rathgeber, Cyrille B.K., Salmon, Yann, Saunder, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stereńczak, Marko, Střelcová, Katarína, Světlík, Jan, Svodoba, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares Ros, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, Steppe, Kathy, Ministerio de Ciencia e Innovación (España), Swiss National Science Foundation, Ministerio de Economía y Competitividad (España), Salomón, Roberto L., Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G.W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bass J.W., Lindner, Marcus, Martínez-Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert-Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Lubica, Doležal, Jiří, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans-Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inke, Rathgeber, Cyrille B.K., Salmon, Yann, Saunder, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stereńczak, Marko, Střelcová, Katarína, Světlík, Jan, Svodoba, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares Ros, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, and Steppe, Kathy

Abstract

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.

Published
2022

9. Data from: The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Author

Salomón, Roberto L., Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G.W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bas J.W., Lindner, Marcus, Martinez-Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Ľubica, Dolezal, Jiri, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inken, Rathgeber, Cyrille B.K., Salmon, Yann, Saunders, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stojanović, Marko, Střelcová, Katarína, Světlík, Jan, Svoboda, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, Steppe, Kathy, Salomón, Roberto L., Peters, Richard L., Zweifel, Roman, Sass-Klaassen, Ute G.W., Stegehuis, Annemiek I., Smiljanic, Marko, Poyatos, Rafael, Babst, Flurin, Cienciala, Emil, Fonti, Patrick, Lerink, Bas J.W., Lindner, Marcus, Martinez-Vilalta, Jordi, Mencuccini, Maurizio, Nabuurs, Gert Jan, van der Maaten, Ernst, von Arx, Georg, Bär, Andreas, Akhmetzyanov, Linar, Balanzategui, Daniel, Bellan, Michal, Bendix, Jörg, Berveiller, Daniel, Blaženec, Miroslav, Čada, Vojtěch, Carraro, Vinicio, Cecchini, Sébastien, Chan, Tommy, Conedera, Marco, Delpierre, Nicolas, Delzon, Sylvain, Ditmarová, Ľubica, Dolezal, Jiri, Dufrêne, Eric, Edvardsson, Johannes, Ehekircher, Stefan, Forner, Alicia, Frouz, Jan, Ganthaler, Andrea, Gryc, Vladimír, Güney, Aylin, Heinrich, Ingo, Hentschel, Rainer, Janda, Pavel, Ježík, Marek, Kahle, Hans Peter, Knüsel, Simon, Krejza, Jan, Kuberski, Łukasz, Kučera, Jiří, Lebourgeois, François, Mikoláš, Martin, Matula, Radim, Mayr, Stefan, Oberhuber, Walter, Obojes, Nikolaus, Osborne, Bruce, Paljakka, Teemu, Plichta, Roman, Rabbel, Inken, Rathgeber, Cyrille B.K., Salmon, Yann, Saunders, Matthew, Scharnweber, Tobias, Sitková, Zuzana, Stangler, Dominik Florian, Stereńczak, Krzysztof, Stojanović, Marko, Střelcová, Katarína, Světlík, Jan, Svoboda, Miroslav, Tobin, Brian, Trotsiuk, Volodymyr, Urban, Josef, Valladares, Fernando, Vavrčík, Hanuš, Vejpustková, Monika, Walthert, Lorenz, Wilmking, Martin, Zin, Ewa, Zou, Junliang, and Steppe, Kathy

Abstract

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes., Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.

Published
2021

13. Water use – from leaf to tree to stand level

Author

Hentschel, Rainer, Geßler, Arthur, Priesack, Eckart, and Bolte, Andreas

Subjects
stabile Isotope, 39 Landwirtschaft, Garten, Trockenstress, water transport, hydrodynamic modeling, physiologische Reaktion, hydrodynamische Modellierung, drought stress, 630 Landwirtschaft, Veterinärmedizin, ddc:630, stable isotopes, physiological response, Wassertransport
Abstract

Im Fokus dieser Arbeit steht die physiologische Reaktion von Einzelbäumen gegenüber Trockenheit. Das angewandte hydrodynamische Xylemwasserfluss (XWF) Model liefert eine hydrologische Abbildung der Einzelbäume. Aufgrund des funktionalen Zusammenhanges zwischen dem Blattwasserpotential und der stomatären Leitfähigkeit erlaubt das XWF Modell eine öko-physiologische Simulation der stomatären Reaktion auf Blattebene. Hieraus ergeben sich auch Rückschlüsse auf die Assimilationsleistung. Als integratives Maß des Verhältnisses zwischen der Kohlenstoffaufnahme und dem Wasserverbrauch werden die stabilen (Jahrring-) Isotope des Kohlen- und des Sauerstoffs analysiert. Des Weiteren werden Messungen des jährlichen Dickenwachstums sowie des Tagesganges der Xylem-Saftflussdichte untersucht. Die XWF Simulationen zeigen eine gute Übereinstimmung mit den Saftflussdichtemessungen an Buchen (Fagus sylvatica L.). Eine effektive stomatäre Regulation der Transpiration während der extreme Trockenheit des Jahres 2003 schütze die untersuchten Buchen vor einer Fehlfunktion des Wassertransportes. Gleichfalls konnte das Wachstum aufrechterhalten werden, was eine Remobilisierung von gespeichertem Kohlenstoff während Zeiten eingeschränkten Gasaustausches nahe legt. Des Weiteren zeigte sich Unterschiede in den (Wasser-) Nutzungsstrategien von Fichten (Picea abies L. Karst.), was auf eine physiologische Prädisposition der Gefährdung einzelner Bäume gegenüber Trockenstress hinweist. Die gemeinsame Betrachtung von hydrodynamischen Simulationen und öko-physiologischen Messungen kann dazu beitragen die komplexen physiologischen Prozesse auf Blattebene abzubilden und diese auf Baumebene zu projizieren. Weiterführend können somit die Vorhersagen des Wasserhaushaltes auf Bestandesebene angepasst und Auswirkungen des Klimawandels besser abgeschätzt werden. This study focuses on the physiological response of individual trees towards drought. The hydrodynamic model of xylem water flow (XWF) applied provides a hydraulic map of the individual trees. Due to the functional linkage between the leaf water status and the stomatal conductance, the XWF model enables an eco-physiological representation of the stomatal response at the leaf level. As an integrative record of the ratio between water loss and carbon gain, the tree ring carbon and oxygen stable isotopes have been analyzed. Furthermore, measurements of seasonal growth and diurnal sap flow densities include in my study. The hydrodynamic XWF simulation shows good agreement with sap flow density measurements of beech trees (Fagus sylvatica L.). It demonstrates that the study trees were able to cope with the extreme drought events of the years 2003 due to a strong limitation of water loss by stomatal closure. The assessment of growth data and stable isotope measurements suggest an increased remobilization of stored carbohydrates during periods of limited gas exchange. Furthermore, differences in the resource use strategies of Norway spruce trees (Picea abies L. Karst.) suggest a physiological predisposition of individual trees toward drought stress. The combined investigation of hydrodynamic modeling and eco-physiological approaches helps to bridge the gap between the detailed examinations of physiological processes at the leaf level to the forecast of water use at the tree level. Thus, predictions of the water balance at the stand level may be adjusted for a better representation of the impact of climate change.

Published
2016

15. Water use – from leaf to tree to stand level

Author

Geßler, Arthur, Priesack, Eckart, Bolte, Andreas, Hentschel, Rainer, Geßler, Arthur, Priesack, Eckart, Bolte, Andreas, and Hentschel, Rainer

Abstract

Im Fokus dieser Arbeit steht die physiologische Reaktion von Einzelbäumen gegenüber Trockenheit. Das angewandte hydrodynamische Xylemwasserfluss (XWF) Model liefert eine hydrologische Abbildung der Einzelbäume. Aufgrund des funktionalen Zusammenhanges zwischen dem Blattwasserpotential und der stomatären Leitfähigkeit erlaubt das XWF Modell eine öko-physiologische Simulation der stomatären Reaktion auf Blattebene. Hieraus ergeben sich auch Rückschlüsse auf die Assimilationsleistung. Als integratives Maß des Verhältnisses zwischen der Kohlenstoffaufnahme und dem Wasserverbrauch werden die stabilen (Jahrring-) Isotope des Kohlen- und des Sauerstoffs analysiert. Des Weiteren werden Messungen des jährlichen Dickenwachstums sowie des Tagesganges der Xylem-Saftflussdichte untersucht. Die XWF Simulationen zeigen eine gute Übereinstimmung mit den Saftflussdichtemessungen an Buchen (Fagus sylvatica L.). Eine effektive stomatäre Regulation der Transpiration während der extreme Trockenheit des Jahres 2003 schütze die untersuchten Buchen vor einer Fehlfunktion des Wassertransportes. Gleichfalls konnte das Wachstum aufrechterhalten werden, was eine Remobilisierung von gespeichertem Kohlenstoff während Zeiten eingeschränkten Gasaustausches nahe legt. Des Weiteren zeigte sich Unterschiede in den (Wasser-) Nutzungsstrategien von Fichten (Picea abies L. Karst.), was auf eine physiologische Prädisposition der Gefährdung einzelner Bäume gegenüber Trockenstress hinweist. Die gemeinsame Betrachtung von hydrodynamischen Simulationen und öko-physiologischen Messungen kann dazu beitragen die komplexen physiologischen Prozesse auf Blattebene abzubilden und diese auf Baumebene zu projizieren. Weiterführend können somit die Vorhersagen des Wasserhaushaltes auf Bestandesebene angepasst und Auswirkungen des Klimawandels besser abgeschätzt werden., This study focuses on the physiological response of individual trees towards drought. The hydrodynamic model of xylem water flow (XWF) applied provides a hydraulic map of the individual trees. Due to the functional linkage between the leaf water status and the stomatal conductance, the XWF model enables an eco-physiological representation of the stomatal response at the leaf level. As an integrative record of the ratio between water loss and carbon gain, the tree ring carbon and oxygen stable isotopes have been analyzed. Furthermore, measurements of seasonal growth and diurnal sap flow densities include in my study. The hydrodynamic XWF simulation shows good agreement with sap flow density measurements of beech trees (Fagus sylvatica L.). It demonstrates that the study trees were able to cope with the extreme drought events of the years 2003 due to a strong limitation of water loss by stomatal closure. The assessment of growth data and stable isotope measurements suggest an increased remobilization of stored carbohydrates during periods of limited gas exchange. Furthermore, differences in the resource use strategies of Norway spruce trees (Picea abies L. Karst.) suggest a physiological predisposition of individual trees toward drought stress. The combined investigation of hydrodynamic modeling and eco-physiological approaches helps to bridge the gap between the detailed examinations of physiological processes at the leaf level to the forecast of water use at the tree level. Thus, predictions of the water balance at the stand level may be adjusted for a better representation of the impact of climate change.

Published
2016

16. Grantørkeprosjektet. Sluttrapport

Author

Solberg, Svein, Andreassen, Kjell, Antón-Fernández, Clara, Børja, Isabella, Čermák, Jan, Dalsgaard, Lise, Eklundh, Lars, Garcia, Monica, Gessler, Arthur, Godbold, Douglas L., Hentschel, Rainer, Kayler, Zachary, Madsen, Palle, Nadezhdina, Nadezhda, Rosner, Sabine, Světlík, Jan, Tollefsrud, Mari Mette, Tveito, Ole Einar, and Øyen, Bernt-Håvard

Subjects
VDP::Forestry: 915, Klima, Gran, Drought, Climate, Norway spruce, VDP::Skogbruk: 915, Tørke
Abstract

Grantørkeprosjektet har fokusert på tørkeproblemer på gran i lavlandet på Østlandet. Toppskranting og avdøing har forekommet på enkelte lokaliteter i veksterlige granbestand i hkl 3-4. Gjentatte befaringer av slike skader gjennom de siste 20-25 år har tydet på at tørke er hovedårsaken, men at det er komplekse årsaksforhold. Det har vært et hovedmål i prosjektet å stille en diagnose på disse skadene. Videre har prosjektet fokusert på klimaendringene og risikoen for at tørkeskader på gran kan øke over tid. Endelig har prosjektet også tilrettelagt for en diskusjon mellom forskning, forvaltning og praktikere om skogbehandling og alternativer til konvensjonell skogbehandling med gran for å møte klimaendringene. Toppskrantingen som ble undersøkt i dette prosjektet hadde de samme symptomer som observert i mange tidligere befaringer, dvs. misfarging og avdøing av topper og gradvis forverring av skadene nedover i krona, etterfulgt av avdøing av hele trær. Resultatene bekrefter at tørkestress om sommeren har vært utløsende faktor for skadene, og at de undersøkte skadene i dette prosjektet ble utløst av moderat tørke i somrene 2004-06. Disse somrene hadde perioder i juni og juli med høy fordampning pga høye temperaturer og vedvarende vind, og lite nedbør. Dette førte til nedbørunderskudd og moderat tørkestress. Flere påfølgende år med moderat tørkestress har ført til kavitasjon i vannledningsbanene i stammen hos en del trær. Deler av yteveden har blitt satt ut av spill som vannledningsbaner. Utviklingen av høyde- og diametervekst, samt funn av tørkeringer og traumatiske harpikskanaler i disse årene understøtter at det har vært et tørkestress.....

Published
2013

20. Modeling acclimation of leaf photosynthesis to atmospheric CO 2 enrichment

Author

Biernath, Christian, Bittner, Sebastian, Klein, Christian, Gayler, Sebastian, Hentschel, Rainer, Hoffmann, Peter, Högy, Petra, Fangmeier, Andreas, and Priesack, Eckart

Subjects
*ACCLIMATIZATION (Plants), *PHOTOSYNTHESIS, *COMPOSITION of leaves, *ATMOSPHERIC carbon dioxide, *LIGHT interception by plants, *ACTIVE nitrogen, *SIMULATION methods & models
Abstract

Abstract: In this study, we developed and analyzed a new model for the simulation of photosynthetic active nitrogen (N P ) turnover dynamics in crops and assessed its impact on the acclimation of canopy photosynthesis to atmospheric CO 2 enrichment. Typical canopy models assume a vertical exponential decline of light interception following the Beer–Lambert law and vertical distributions of leaf N P contents directly proportional to the light distribution. This assumption is often inconsistent with experimental observations. We therefore modified and extended the photosynthesis model of the GECROS crop model to consider the trade-off that occurs between the use of degraded N P for plant growth and the synthesis of new N P . This model extension thus enabled the examination of the CO 2-induced down-regulation of photosynthesis hypothesis using a crop model. The simulation results of the original and modified GECROS model were compared and evaluated based upon measurements of field-grown spring wheat. The modified GECROS model better simulated the dynamics of crop growth under varying atmospheric CO 2 concentrations. Furthermore, the application of different temperature functions to N P degradation strongly influenced the simulation results, revealing the necessity for improving the understanding of the temperature dependence of N P turnover for different crop species and varieties. In conclusion, the redistribution of nitrogen within the plant and its alternative use either for growth or the optimization of the photosynthetic apparatus is an important mechanism for crop growth acclimation to regionally changing climatic conditions and in particular, atmospheric CO 2 enrichment. [Copyright &y& Elsevier]

Published
2013
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