Reaction of siberian subarctic larch trees to abrupt climatic changes derived from tree-ring and isotope data

The Siberian Subarctic region is highly interesting for the investigation of climatic and environmental changes because of its sensitivity to climate change Vaganov and Shiyatov 1999; Körner 2000; IPCC 2007. The application of long-term tree-ring chronologies (a natural archive for studies of climatic changes) can help us to evaluate climatic and environmental changes in the past and to understand the mechanisms of these changes. Stable isotopes in tree rings provide an additional proxy for paleoclimate with a defined annual resolution Leng 2006.It is well known that volcanic eruptions play an important role in climatic changes. Major volcanic eruptions eject particles and aerosols into the stratosphere leading to global cooling for up to several years due to a decrease in incoming solar radiation Robock 2000; Zielinski 2000. Recently, many reports about the influence of volcanic eruptions on tree ring width have been published Baillie 1994; Briffa et al. 1998; Zielinski 2000; D’Arrigo 2001; Krakauer and Randerson 2003. Only few studies were carried out to analyze the isotopic composition in trees in response to volcanic eruptions Battipaglia et al. 2007 but none for the high latitudes of Eurasia.A prominent example is the "dust-veil" event (AD 536) Baillie, 1994, which had a catastrophic effect on the environment and civilization. Many scientists tried to explain this event Baillie 1994; Zielinski et al. 1994; Briffa et al. 1998; Stothers 1999. One hypothesis is that dry fogs spawned by large volcanic eruptions cooled the climate during that time by partially blocking incident sunlight and perturbed the atmospheric circulation patterns. The climatic and epidemiological consequences of seven intense volcanic dry fogs of the past 21 centuries, detected in Europe and the Middle East, were investigated using historical reports, supplemented by tree-ring data and polar-ice acidity measurements. An alternative hypothesis suggests that cosmic phenomena (asteroid or comet) could have caused the strong climatic changes during this time Rigby et al. 2004. European chronologies showed a decreasing radial growth during 10 years after the AD 536 event Baillie 1994; Stothers, 1999.The goal of this paper is to reveal the reaction of larch trees from the Siberian Subarctic (Eastern Taimyr) after the abrupt climatic change in AD 536, an event, which was characterized by cooling throughout the vast territory of Subarctic Eurasia. Tree rings and isotopic data (δ13C, δ18O) were examined for a better understanding of physiological responses of trees to climatic and environmental changes. ...