"Dendroisotopes": Spatial and temporal variability of stable oxygen isotopes in wood of pine trees on Corsica as indicators of current and past hydroclimate
Project staff:
Abstract:
A dendroisotopic study shall reveal oxygen isotope variability in wood, needle water and xylem water from pine trees on Corsica in intraannual resolution. The study will be based on two pine species (Pinus nigra and Pinus pinaster) along an east-west transect through the Renoso massif in the south of the island. Due to the alignment, the selected sites cover the full range of Corsican climate from coastal locations with mediterranean climate to alpine conditions with continuous snow cover for several months. The overall aim of the study is to enhance our understanding of the physiological control and the environmental forcing of short-term oxygen isotope variability in pine trees in a mediterranean ecosystem. High-resolution hydroclimatic and dendroecologic data collected within the project bundle „CorsicArchive“ will help to interpret the oxygen isotope chronologies and enables us to trace back sources of isotope variability, e.g. different water sources, origin of air masses. The combination of short-term high-resolution chronologies with already existing long-term chronologies in annual resolution enables us to transfer the short-term variability on a longer timescale and to model changes of isotope fractionation processes under different climatic regimes and climate changes scenarios in the Mediterranean area.
Description:
Oxygen isotope ratios in tree rings depend on several factors:
• δ18O value of the water taken up by the roots
• Enrichment of 18O in the leafwater due to fractionation processes during transpiration
• Biochemical isotope fractionations during biosynthesis including fractionations during photosynthetic synthesis of carbohydrates and fractionations by postphotosynthetic isotope exchange during cellulose formation
• 18O vs. 16O exchange reactions between ascending xylem water and phloemconcentrate removed from the leaves
Previous isotope investigations on Corsica showed that the oxygen isotope variability between different locations is considerably high. A distinct climate factor which is responsible for the variability could not be identified yet due to the low (annual) resolution of the chronologies. For a better understanding of the long-term isotope variability it is necessary to understand the causes for short-term variability. Therefore, the overall aim of the current project is to enhance our understanding of the physiological control and the environmental forcing of short-term oxygen isotope variability in tree rings on Corsica. Intra-annual isotope chronologies shall be developed from Pinus nigra and Pinus pinaster to answer the following research questions:
1. How strong is isotope fractionation during the various fractionation steps between water uptake and cellulose synthesis?
2. What are the main water sources used by the trees and how do they vary over the vegetaion period?
3. To what degree are the isotope signatures of soil water and precipitation reflected in the tree ring?
4. How do climatic extremes influence the intraannual isotope variability in tree rings over shorter and longer time scales?
Instead of a long-term palaeoclimate-perspective, the current project follows an actualistic approach with high-resolution. The establishment of intraannual isotope chronologies from current vegetaion periods is therefore the major task. Beside the recent years of known atmospheric circulation conditions, we also plan to analyse ancient vegetaion periods from older tree rings formed in different climatic regimes, e.g. during the Little Ice Age (LIA). Chronologies covering these periods were already established during a previous project. This allows us to transfer the short-term variability on a longer timescale and to model changes of isotope fractionation processes under different climatic regimes.
Publications and poster presentations:
2019 - Szymczak, S.; Garel, E.; Huneau, F.; Santoni, S.; Bendix, J.; Knerr, I.; Trachte, K.; Barth, J.; Juhlke, T.; van Geldern, R.; Häusser, M. & Bräuning, A. (2019-10-27). Auswirkungen klimatischer Extremjahre auf das Baumwachstum von Kiefern auf Korsika. Presented at Jahrestagung des AK Klima, Jesteburg/Germany.
- Szymczak, S.; Bräuning, A.; Häusser, M.; Garel, E.; Huneau, F. & Santoni, S. (2019): The relationship between climate and the intra-annual oxygen isotope patterns from pine trees: a case study along an elevation gradient on Corsica, France. Annals of Forest Science 76, 1-14 DOI: http://dx.doi.org/10.1007/s13595-019-0860-9.
- Szymczak, S.; Bräuning, A.; Barth, J.; Juhlke, T.; van Geldern, R.; Garel, E.; Huneau, F. & Santoni, S. (2019-05-09). Disentangling different water sources along an altitudinal gradient with intra-annual oxygen isotope patterns. Presented at TRACE-Conference, Caserta/Italy.
- Szymczak, S.; Bräuning, A.; Häusser, M.; Garel, E.; Huneau, F. & Santoni, S. (2019-02-01). Intra-annual oxygen isotope chronologies detect changing climate conditions in seasonal resolution in the high mountains of Corsica. Presented at Jahrestagung des AK Hochgebirge, Augsburg/Germany.
2018 - Szymczak, S.; Bräuning, A. & Joachimski, M. (2018): Long-term oxygen isotope chronologies from a Mediterranean island. TRACE Volume 16, 46-53.
2017 - Szymczak, S. & Bräuning, A. (2017-05-18). Long-term oxygen isotope chronologies from a Mediterranean island. Presented at TRACE-Conference, Svetlogorsk/Russia.
- Szymczak, S. & Bräuning, A. (2017-05-13). Klimaökologische Abhängigkeit von Sauerstoffisotopen in Jahrringzellulose von Schwarzkiefern (Pinus nigra ssp. laricio) auf Korsika. Presented at Jahrestreffen des AK Biogeographie, Erlangen/Germany.
2014 - Szymczak, S.; Hetzer, T.; Bräuning, A.; Joachimski, M.; Leuschner, H. & Kuhlemann, J. (2014): Combining wood anatomy and stable isotope variations in a 600-year multi-parameter climate reconstruction from Corsican Pine. Quaternary Science Reviews 101, 146-158 DOI: http://dx.doi.org/10.1016/j.quascirev.2014.07.010.
2012 - Szymczak, S.; Joachimski, M.; Bräuning, A.; Hetzer, T. & Kuhlemann, J. (2012): A 560 yr summer temperature reconstruction for the Western Mediterranean basin based on stable carbon isotopes from Pinus nigra ssp. laricio (Corsica/France). Climate of the Past 8, 1737-1749 DOI: http://dx.doi.org/10.5194/cp-8-1737-2012.
- Szymczak, S.; Joachimski, M.; Bräuning, A.; Hetzer, T. & Kuhlemann, J. (2012): Are pooled tree ring d13C and d18O series reliable climate archives? – a case study of Pinus nigra ssp. laricio (Corsica/France). Chemical Geology 308-309, 40-49 DOI: http://dx.doi.org/10.1016/j.chemgeo.2012.03.013.
2011 - Szymczak, S.; Joachimski, M.; Bräuning, A.; Hetzer, T. & Kuhlemann, J. (2011): Comparison of whole wood and cellulose carbon and oxygen isotope series from Pinus nigra ssp. laricio (Corsica/France). Dendrochronologia 29, 219-226 DOI: http://dx.doi.org/10.1016/j.dendro.2011.04.001.