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1. Spatial variability and temporal trends in water-use efficiency of European forests

Author

Tom Levanič, Ben Poulter, John S. Waterhouse, Emilia Gutiérrez, David Frank, Danny McCarroll, Iain Robertson, Laia Andreu-Hayles, Håkan Grudd, Tatjana Boettger, Fortunat Joos, Gerd Helle, Peter M. Wynn, Ingo Heinrich, Isabel Dorado Liñán, Markus Leuenberger, Emmi Hilasvuori, Giles H.F. Young, Eloni Sonninen, Matthias Saurer, Kerstin Treydte, Ewan J. Woodley, Ian J. Fairchild, Rolf T. W. Siegwolf, Mary Gagen, Risto Jalkanen, Hans W. Linderholm, Renato Spahni, Michael Friedrich, Marika Haupt, Neil J. Loader, Paul Scherrer Institute, Villigen, Oeschger Centre for Climate Change Research (OCCR), University of Bern, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Department of Geography [Swansea], Swansea University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Universitat de Barcelona (UB), University of Birmingham [Birmingham], University of Hohenheim, Finnish Museum of Natural History (LUOMUS), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Bolin Centre for Climate Research, Stockholm University, Finnish Forest Research Institute (METLA), Natural Resources Institute Finland (LUKE), Slovenian Forestry Institute, University of Gothenburg (GU), Anglia Ruskin University (ARU), Lancaster Environment Centre, Lancaster University, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of Helsinki, and Universitat de Barcelona

Subjects
0106 biological sciences, Stomatal conductance, Time Factors, Dendrochronology, 010504 meteorology & atmospheric sciences, Climate Change, ta1171, Climate change, Forests, Atmospheric sciences, 01 natural sciences, Carbon Cycle, Trees, Water Cycle, Canvi climàtic, Environmental Chemistry, Ecosystem, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Dendrocronologia, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Hydrology, Climatology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Carbon Isotopes, Global and Planetary Change, Geography, Ecology, Boscos, Vegetation, Carbon Dioxide, Models, Theoretical, 15. Life on land, Climatic changes, ta4112, Climatic change, Europe, 13. Climate action, Climatologia, Spatial ecology, Common spatial pattern, Spatial variability, Europa, Temperate rainforest, 010606 plant biology & botany, Canvis climàtics
Abstract

The increasing carbon dioxide (CO2) concentration in the atmosphere in combination with climatic changes throughout the last century are likely to have had a profound effect on the physiology of trees: altering the carbon and water fluxes passing through the stomatal pores. However, the magnitude and spatial patterns of such changes in natural forests remain highly uncertain. Here, stable carbon isotope ratios from a network of 35 tree-ring sites located across Europe are investigated to determine the intrinsic water-use efficiency (iWUE), the ratio of photosynthesis to stomatal conductance from 19012000. The results were compared with simulations of a dynamic vegetation model (LPX-Bern 1.0) that integrates numerous ecosystem and landatmosphere exchange processes in a theoretical framework. The spatial pattern of tree-ring derived iWUE of the investigated coniferous and deciduous species and the model results agreed significantly with a clear south-to-north gradient, as well as a general increase in iWUE over the 20th century. The magnitude of the iWUE increase was not spatially uniform, with the strongest increase observed and modelled for temperate forests in Central Europe, a region where summer soil-water availability decreased over the last century. We were able to demonstrate that the combined effects of increasing CO2 and climate change leading to soil drying have resulted in an accelerated increase of iWUE. These findings will help to reduce uncertainties in the land surface schemes of global climate models, where vegetationclimate feedbacks are currently still poorly constrained by observational data.

Published
2014
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2. Comparing the performance of different stomatal conductance models using modelled and measured plant carbon isotope ratios (δ13C): implications for assessing physiological forcing

Author

John S. Waterhouse, Giles H.F. Young, Mary Gagen, Paul B. Alton, Iain Robertson, Ewan J. Woodley, V. R. Switsur, Per Bodin, Danny McCarroll, Risto Jalkanen, and Neil J. Loader

Subjects
Hydrology, Carbon Isotopes, Global and Planetary Change, Stomatal conductance, Ecology, δ13C, Replicate, Forcing (mathematics), Models, Theoretical, Atmospheric sciences, Europe, Goodness of fit, Isotopes of carbon, Evapotranspiration, Plant Stomata, Dendrochronology, Environmental Chemistry, Environmental science, Plant Physiological Phenomena, General Environmental Science
Abstract

Accurate modelling of long-term changes in plant stomatal functioning is vital to global climate change studies because changes in evapotranspiration influence temperature via physiological forcing of the climate. Various stomatal models are included in land surface schemes, but their robustness over longer timescales is difficult to validate. We compare the performance of three stomatal models, varying in their degree of complexity, and coupled to a land surface model. This is done by simulating the carbon isotope ratio of tree leaves (δ(13) Cleaf ) over a period of 53 years, and comparing the results with carbon isotope ratios obtained from tree rings (δ(13) Cstem ) measured at six sites in northern Europe. All three stomatal models fail to capture the observed inter-annual variability in the measured δ(13) Cstem time series. However, the Soil-Plant-Atmosphere (SPA) model performs significantly better than the Ball-Berry (BB) or COX models when tested for goodness of fit against measured δ(13) Cstem . The δ(13) Cleaf time series simulated using the SPA model are significantly positively correlated (p < 0.05) with measured results over the full time period tested, at all six sites. The SPA model underestimates inter-annual variability measured in δ(13) Cstem , but is no worse than the BB model and significantly better than the COX model. The inability of current models to adequately replicate changes in stomatal response to rising levels of CO2 concentrations, and thus to quantify the associated physiological forcing, warrants further investigation. © 2013 Blackwell Publishing Ltd. (Less)

Published
2013

3. Spatial variability and temporal trends in water-use efficiency of European forests.

Author

Saurer, Matthias, Spahni, Renato, Frank, David C., Joos, Fortunat, Leuenberger, Markus, Loader, Neil J., McCarroll, Danny, Gagen, Mary, Poulter, Ben, Siegwolf, Rolf T.W., Andreu‐Hayles, Laia, Boettger, Tatjana, Dorado Liñán, Isabel, Fairchild, Ian J., Friedrich, Michael, Gutierrez, Emilia, Haupt, Marika, Hilasvuori, Emmi, Heinrich, Ingo, and Helle, Gerd

Subjects
WATER requirements for trees, FORESTS & forestry, CARBON dioxide & the environment, TREES & climate, PHOTOSYNTHESIS
Abstract

The increasing carbon dioxide (CO2) concentration in the atmosphere in combination with climatic changes throughout the last century are likely to have had a profound effect on the physiology of trees: altering the carbon and water fluxes passing through the stomatal pores. However, the magnitude and spatial patterns of such changes in natural forests remain highly uncertain. Here, stable carbon isotope ratios from a network of 35 tree-ring sites located across Europe are investigated to determine the intrinsic water-use efficiency ( iWUE), the ratio of photosynthesis to stomatal conductance from 1901 to 2000. The results were compared with simulations of a dynamic vegetation model (LPX-Bern 1.0) that integrates numerous ecosystem and land-atmosphere exchange processes in a theoretical framework. The spatial pattern of tree-ring derived iWUE of the investigated coniferous and deciduous species and the model results agreed significantly with a clear south-to-north gradient, as well as a general increase in iWUE over the 20th century. The magnitude of the iWUE increase was not spatially uniform, with the strongest increase observed and modelled for temperate forests in Central Europe, a region where summer soil-water availability decreased over the last century. We were able to demonstrate that the combined effects of increasing CO2 and climate change leading to soil drying have resulted in an accelerated increase in iWUE. These findings will help to reduce uncertainties in the land surface schemes of global climate models, where vegetation-climate feedbacks are currently still poorly constrained by observational data. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

4. Comparing the performance of different stomatal conductance models using modelled and measured plant carbon isotope ratios (δ13C): implications for assessing physiological forcing.

Author

Bodin, Per E., Gagen, Mary, McCarroll, Danny, Loader, Neil J., Jalkanen, Risto, Robertson, Iain, R Switsur, Vincent, Waterhouse, John S., Woodley, Ewan J., Young, Giles H. F., and Alton, Paul B.

Subjects
CARBON content of plants, CARBON isotopes, STOMATA, EVAPOTRANSPIRATION, CLIMATE change
Abstract

Accurate modelling of long-term changes in plant stomatal functioning is vital to global climate change studies because changes in evapotranspiration influence temperature via physiological forcing of the climate. Various stomatal models are included in land surface schemes, but their robustness over longer timescales is difficult to validate. We compare the performance of three stomatal models, varying in their degree of complexity, and coupled to a land surface model. This is carried out by simulating the carbon isotope ratio of tree leaves (δ13Cleaf) over a period of 53 years, and comparing the results with carbon isotope ratios obtained from tree rings (δ13Cstem) measured at six sites in northern Europe. All three stomatal models fail to capture the observed interannual variability in the measured δ13Cstem time series. However, the Soil-Plant-Atmosphere ( SPA) model performs significantly better than the Ball-Berry ( BB) or COX models when tested for goodness-of-fit against measured δ13Cstem. The δ13Cleaf time series simulated using the SPA model are significantly positively correlated ( P < 0.05) with measured results over the full time period tested, at all six sites. The SPA model underestimates interannual variability measured in δ13Cstem, but is no worse than the BB model and significantly better than the COX model. The inability of current models to adequately replicate changes in stomatal response to rising levels of CO2 concentrations, and thus to quantify the associated physiological forcing, warrants further investigation. [ABSTRACT FROM AUTHOR]

Published
2013
Full Text
View/download PDF

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