climate reconstruction; stable isotopes; tree rings; tree physiology; Boreal forests; elevated CO2; Siberia; Alps; Medieval optimum; Little ice age; photosynthesis; carbon dioxide
Kress A., Saurer M., Siegwolf R. T. W., Frank D. C., Esper J., Bugmann H. (2010), A 350 year drought reconstruction from Alpine tree ring stable isotopes, in Global Biogeochemical Cycles
, 24, 1-2.
Sidorova O. V., Siegwolf R. T. W., Saurer M., Naurzbaev1 M. M., Shashkin1 A. V., Vaganov1 E. A. (2010), Spatial patterns of climatic changes in the Eurasian north reflected in Siberian larch tree-ring parameters and stable isotopes, in Global Change Biology
, 16, 1003-1018.
Knorre A. A., Siegwolf R. T. W., Saurer M., Sidorova O. V., Vaganov E. A., Kirdyanov A. V. (2010), Twentieth century trends in tree ring stable isotopes (d13C and d18O) of Larix sibirica under dry conditions in the forest steppe in Siberia, in Journal of Geophysical Research-Biogeosciences
, 115, 1-2.
Sidorova O. V., Siegwolf R. T. W., Saurer M., Shashkin A. V., Knorre A. A., Prokushkin A. S., Vaganov E. A., Kirdyanov A. V. (2009), Do centennial tree-ring and stable isotope trends of Larix gmelinii (Rupr.) Rupr. indicate increasing water shortage in the Siberian north?, in Oecologia
, 161, 825-835.
Reynolds-Henne C. E., Saurer M., Siegwolf R. T. W. (2009), Temperature versus species-specific influences on the stable oxygen isotope ratio of tree rings, in Trees-Structure and Function
, 23, 801-811.
Olga V. Sidorova, Matthias Saurer, Vladimir S. Myglan, Anja Eichler, Margit Schwikowski, Aleksander V. Kirdyanov, Marina V. Bryukhanova, Oksana V. Gerasimova, Ivan A. Kalugin, Andrey V. Daryin, Rolf T. W. Siegwolf, A multi-proxy approach for revealing recent climatic changes in the Russian Altai, in Climate Dynamics
, 1, 1-2.
High-latitude and high altitude forests are sensitive ecosystems that are more exposed to global warming in recent decades than forests of the temperate zones. As a result of the accelerating climate change, these forests may undergo severe changes regarding spatial distribution and species composition, the carbon, water and nitrogen cycles. This will have tremendous consequences for the sustainable functioning of the ecosystems and potential feedbacks to the atmosphere, such as increased release of greenhouse gases from soils. Insight into extreme past climate conditions and the response of Boreal and Alpine forests to these conditions provides an invaluable analogy for the potential future response. Trees from temperature-limited sites are also known as sensitive proxies for climate reconstruction, while the availability of well-preserved wood in these regions enable the deciphering of past environmental conditions for centuries up to millennia.In this project, our main goal is to obtain a comprehensive description of the climatic and environmental changes during pronounced warm and cool periods of the past 1500 years. We want to achieve this goal by addressing the following three objectives:1) we aim to better quantify the magnitude of temperature and precipitation variability for known periods of extreme climate conditions, focusing on the cold anomaly around AD 536, the Medieval optimum period AD 900-1150, the maximum of the so-called “little ice age” period (AD 1600-1815) and the last century (1900 to present),2) we will use the combined analysis of tree-ring width, carbon and oxygen isotopes and physiological models to decipher the response of the trees in terms of photosynthesis and water-use during these periods,3) and we want to determine the spatial and temporal coherence of large-scale climate events for Europe and northern Eurasia.With the proposed periods, we cover climate anomalies on different time-scales (years to centuries), different rates of change (from sudden to gradual) and of different direction (warming or cooling). All these events are known to be large-scale events, but with different spatial extent. We have access to unique dated tree-ring material from three sites in Northern Siberia and one site from the Alps that cover the investigation periods. The site coverage will enable us to retrieve large-scale climatic connections, considering also oxygen isotope variations in ice-cores from Altai and Greenland and other published tree-ring records for comparison. We will use ring-width as a measure of growth and stable isotope ratios of carbon and oxygen of tree-ring cellulose as a measure of photosynthesis and water-use, while both isotopes are also related to temperature and precipitation. By applying a coupled photosynthesis-isotope fractionation model, which is driven by microclimate, photosynthesis, and soil water balance, we will be able to relate climatic to physiological changes. This project combines in an innovative way aspects of climatology, physiology and modeling, and applies them to a world-wide unique data set of historic wood. The results of the project will enable us to better understand the response of trees in temperature-limited environment to a changing climate.