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1. Recent human-induced atmospheric drying across Europe unprecedented in the last 400 years

Author

Treydte, Kerstin, Liu, Laibao, Padrón, Ryan S., Martínez-Sancho, Elisabet, Babst, Flurin, Frank, David C., Gessler, Arthur, Kahmen, Ansgar, Poulter, Benjamin, Seneviratne, Sonia I., Stegehuis, Annemiek I., Wilson, Rob, Andreu-Hayles, Laia, Bale, Roderick, Bednarz, Zdzislaw, Boettger, Tatjana, Berninger, Frank, Büntgen, Ulf, Daux, Valerie, Dorado-Liñán, Isabel, Esper, Jan, Friedrich, Michael, Gagen, Mary, Grabner, Michael, Grudd, Håkan, Gunnarsson, Björn E., Gutiérrez, Emilia, Hafner, Polona, Haupt, Marika, Hilasvuori, Emmi, Heinrich, Ingo, Helle, Gerhard, Jalkanen, Risto, Jungner, Högne, Kalela-Brundin, Maarit, Kessler, Andreas, Kirchhefer, Andreas, Klesse, Stephan, Krapiec, Marek, Levanič, Tom, Leuenberger, Markus, Linderholm, Hans W., McCarroll, Danny, Masson-Delmotte, Valérie, Pawelczyk, Slawomira, Pazdur, Anna, Planells, Octavi, Pukiene, Rutile, Rinne-Garmston, Katja T., Robertson, Iain, Saracino, Antonio, Saurer, Matthias, Schleser, Gerhard H., Seftigen, Kristina, Siegwolf, Rolf T. W., Sonninen, Eloni, Stievenard, Michel, Szychowska-Krapiec, Elzbieta, Szymaszek, Malgorzata, Todaro, Luigi, Waterhouse, John S., Weigl-Kuska, Martin, Weigt, Rosemarie B., Wimmer, Rupert, Woodley, Ewan J., Vitas, Adomas, Young, Giles, and Loader, Neil J.

Published
2024
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9. Limits and Strengths of Tree-Ring Stable Isotopes

Author

Andreu-Hayles, Laia, Lévesque, Mathieu, Guerrieri, Rossella, Siegwolf, Rolf T. W., Körner, Christian, Meinzer, Frederick C., Series Editor, Niinemets, Ülo, Series Editor, Siegwolf, Rolf T. W., editor, Brooks, J. Renée, editor, Roden, John, editor, and Saurer, Matthias, editor

Published
2022
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18. 20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

Author

Keller, Kathrin M, Lienert, Sebastian, Bozbiyik, Anil, Stocker, Thomas F, Churakova, Olga V, Frank, David C, Klesse, Stefan, Koven, Charles D, Leuenberger, Markus, Riley, William J, Saurer, Matthias, Siegwolf, Rolf, Weigt, Rosemarie B, and Joos, Fortunat

Subjects
Physical Geography and Environmental Geoscience, Biological Sciences, Ecology, Earth Sciences, Plant Biology, Environmental Sciences, Meteorology & Atmospheric Sciences, Physical geography and environmental geoscience, Environmental management
Abstract

Measurements of the stable carbon isotope ratio (δ13C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO2 partial pressure in the intercellular cavities and the atmosphere (ci=ca) and of the ratio of assimilation to stomatal conductance, termed intrinsic wateruse efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the Land Surface Processes and Exchanges (LPX-Bern) dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ13C measurements on leaves, though modeled 13C discrimination by C3 trees is smaller in arid regions than measured. A compilation of 76 tree-ring records, mainly from Europe, boreal Asia, and western North America, suggests on average small 20th century changes in isotopic discrimination and in ci=ca and an increase in iWUE of about 27% since 1900. LPXBern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss by transpiration. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as that revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO2. The results suggest that the downregulation of ci=ca and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or that there may be problems associated with the implementation of conductance, assimilation, and related adjustment processes on long-term environmental changes.

Published
2017

20. Recent human-induced atmospheric drying across Europe unprecedented in the last 400 years

Author

Treydte, Kerstin, primary, Liu, Laibao, additional, Padrón, Ryan S., additional, Martínez-Sancho, Elisabet, additional, Babst, Flurin, additional, Frank, David C., additional, Gessler, Arthur, additional, Kahmen, Ansgar, additional, Poulter, Benjamin, additional, Seneviratne, Sonia I., additional, Stegehuis, Annemiek I., additional, Wilson, Rob, additional, Andreu-Hayles, Laia, additional, Bale, Roderick, additional, Bednarz, Zdzislaw, additional, Boettger, Tatjana, additional, Berninger, Frank, additional, Büntgen, Ulf, additional, Daux, Valerie, additional, Dorado-Liñán, Isabel, additional, Esper, Jan, additional, Friedrich, Michael, additional, Gagen, Mary, additional, Grabner, Michael, additional, Grudd, Håkan, additional, Gunnarsson, Björn E., additional, Gutiérrez, Emilia, additional, Hafner, Polona, additional, Haupt, Marika, additional, Hilasvuori, Emmi, additional, Heinrich, Ingo, additional, Helle, Gerhard, additional, Jalkanen, Risto, additional, Jungner, Högne, additional, Kalela-Brundin, Maarit, additional, Kessler, Andreas, additional, Kirchhefer, Andreas, additional, Klesse, Stephan, additional, Krapiec, Marek, additional, Levanič, Tom, additional, Leuenberger, Markus, additional, Linderholm, Hans W., additional, McCarroll, Danny, additional, Masson-Delmotte, Valérie, additional, Pawelczyk, Slawomira, additional, Pazdur, Anna, additional, Planells, Octavi, additional, Pukiene, Rutile, additional, Rinne-Garmston, Katja T., additional, Robertson, Iain, additional, Saracino, Antonio, additional, Saurer, Matthias, additional, Schleser, Gerhard H., additional, Seftigen, Kristina, additional, Siegwolf, Rolf T. W., additional, Sonninen, Eloni, additional, Stievenard, Michel, additional, Szychowska-Krapiec, Elzbieta, additional, Szymaszek, Malgorzata, additional, Todaro, Luigi, additional, Waterhouse, John S., additional, Weigl-Kuska, Martin, additional, Weigt, Rosemarie B., additional, Wimmer, Rupert, additional, Woodley, Ewan J., additional, Vitas, Adomas, additional, Young, Giles, additional, and Loader, Neil J., additional

Published
2023
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27. Weather modifies the spatial extent of carbohydrate transfers from CO2-supplied broad-leaved trees to ectomycorrhizal fungi.

Author

Hobbie, Erik A., Siegwolf, Rolf, Körner, Christian, Steinmann, Katharina, Wilhelm, Markus, Saurer, Matthias, and Keel, Sonja G.

Subjects
*ECTOMYCORRHIZAL fungi, *FUNGAL morphology, *SOLAR radiation, *CARBOHYDRATES, *DROUGHTS, *TREES
Abstract

Background: Weather conditions and fungal morphology may influence spatial and temporal dynamics of carbon transfer to ectomycorrhizal fungi from their tree hosts but field studies of these dynamics are challenging. Methods: Broad-leaved trees in a Swiss forest were labeled with 13C-depleted CO2 from 2001–2005 and 13C traced into ectomycorrhizal sporocarps collected at different distances from those trees. We then correlated distance (zone), year, fungal genus, fungal morphology, and solar radiation against sporocarp δ13C and loge C/N in stepwise regressions. Results: CO2-supplied trees contributed 71 ± 5%, 32 ± 6%, and 19 ± 7% of sporocarp carbon at 0–6, 6–12, and 12–18 m from these trees, respectively. Fungal morphology (rhizomorph presence and ectomycorrhizae hydrophobicity) was uncorrelated with fungal carbon acquisition. After drought in 2003, CO2-supplied trees contributed less carbon in 2004 than in other years to sporocarps and sporocarp loge C/N decreased. In contrast, sporocarp loge C/N peaked in 2005 and contributions from CO2-labeled trees to the 6–12 and 12–18 m zones increased. Solar radiation with a 14–21 day lag correlated negatively with loge C/N. Sporocarp loge C/N correlated positively with δ13C at 0–6 m and negatively elsewhere. Conclusions: These patterns indicated: 1) fungal morphology did not affect carbon transfers, 2) carbohydrates rather than amino acids were transferred across zones to sporocarps (inferred from spatial correlations of loge C/N and δ13C), 3) sporocarp δ13C and loge C/N reflected the last 2–3 weeks of photosynthesis; 4) summer drought and plant allocation influenced the quantity and spatial extent of belowground transfer. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Updating the dual C and O isotope—Gas‐exchange model: A concept to understand plant responses to the environment and its implications for tree rings.

Author

Siegwolf, Rolf T. W., Lehmann, Marco M., Goldsmith, Gregory R., Churakova, Olga V., Mirande‐Ney, Cathleen, Timoveeva, Galina, Weigt, Rosmarie B., and Saurer, Matthias

Subjects
*TREE-rings, *ISOTOPES, *OXYGEN isotopes, *CARBON isotopes, *ISOTOPIC fractionation, *CHLOROPHYLL spectra
Abstract

The combined study of carbon (C) and oxygen (O) isotopes in plant organic matter has emerged as a powerful tool for understanding plant functional responses to environmental change. The approach relies on established relationships between leaf gas exchange and isotopic fractionation to derive a series of model scenarios that can be used to infer changes in photosynthetic assimilation and stomatal conductance driven by changes in environmental parameters (CO2, water availability, air humidity, temperature, nutrients). We review the mechanistic basis for a conceptual model, in light of recently published research, and discuss where isotopic observations do not match our current understanding of plant physiological response to the environment. We demonstrate that (1) the model was applied successfully in many, but not all studies; (2) although originally conceived for leaf isotopes, the model has been applied extensively to tree‐ring isotopes in the context of tree physiology and dendrochronology. Where isotopic observations deviate from physiologically plausible conclusions, this mismatch between gas exchange and isotope response provides valuable insights into underlying physiological processes. Overall, we found that isotope responses can be grouped into situations of increasing resource limitation versus higher resource availability. The dual‐isotope model helps to interpret plant responses to a multitude of environmental factors. Summary statement: We analysed >300 studies making use of the dual carbon and oxygen isotope model (DI‐model). Based on the isotopic patterns, we can draw conclusions on how environmental variables impact photosynthesis and stomatal conductance. The concept was well received and applied to interpret plant environment interactions. Yet, some studies reported nonplausible model results. Evaluating all publications applying the DI‐model revealed most causes for nonplausibility. [ABSTRACT FROM AUTHOR]

Published
2023
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34. Beyond traditional summer air temperature signals in subarctic tree rings using hydrogen and oxygen isotopes

Author

Fonti, Marina, primary, Saurer, Matthias, additional, Porter, Trevor, additional, Zharkov, Mikhail, additional, Barinov, Valentin, additional, Taynik, Anna, additional, Kirdyanov, Alexander, additional, Knorre, Anastasya, additional, Wegmann, Martin, additional, Trushkina, Tatyana, additional, Koshurnikova, Nataly, additional, Vaganov, Eugene, additional, Myglan, Vladimir, additional, Siegwolf, Rolf, additional, and Churakova (Sidorova), Olga, additional

Published
2023
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47. Stable Isotopes in Tree Rings

Author

Siegwolf, Rolf T. W., Brooks, J. Renée, Roden, John, and Saurer, Matthias

Subjects
paleoclimatology, forest management, anthropogenic impacts, biogeochemical studies, Ecology and Environment, bic Book Industry Communication::P Mathematics & science::PS Biology, life sciences::PST Botany & plant sciences::PSTD Plant physiology, bic Book Industry Communication::T Technology, engineering, agriculture::TV Agriculture & farming::TVR Forestry & silviculture: practice & techniques, bic Book Industry Communication::R Earth sciences, geography, environment, planning::RN The environment::RNP Pollution & threats to the environment::RNPG Climate change, bic Book Industry Communication::R Earth sciences, geography, environment, planning::RB Earth sciences::RBX Palaeontology
Abstract

This Open Access volume highlights how tree ring stable isotopes have been used to address a range of environmental issues from paleoclimatology to forest management, and anthropogenic impacts on forest growth. It will further evaluate weaknesses and strengths of isotope applications in tree rings. In contrast to older tree ring studies, which predominantly applied a pure statistical approach this book will focus on physiological mechanisms that influence isotopic signals and reflect environmental impacts. Focusing on connections between physiological responses and drivers of isotope variation will also clarify why environmental impacts are not linearly reflected in isotope ratios and tree ring widths. This volume will be of interest to any researcher and educator who uses tree rings (and other organic matter proxies) to reconstruct paleoclimate as well as to understand contemporary functional processes and anthropogenic influences on native ecosystems. The use of stable isotopes in biogeochemical studies has expanded greatly in recent years, making this volume a valuable resource to a growing and vibrant community of researchers.

Published
2022
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