Abstract

Keywords

Abstract

It is currently not well known how coherent carbon and oxygen isotope chronologies from different species and sites are under temperate climate conditions. Here we investigated nine chronologies from Switzerland covering the last two centuries, including three deciduous species (Fagus sylvatica, Fraxinus excelsior, and Quercus petraea) and three conifer species (Abies alba, Picea abies, and Pinus sylvestris) from sites neither strongly limited by temperature nor precipitation. All of the chronologies except Fraxinus were significantly correlated to at least one other chronology. Correlations between different species of the same site were of similar strength to correlations between the sites. We observed a strong common high-frequency (interannual) signal for the ? 13C chronologies, whereas the low-frequency (decadal-scale) signal was more similar among the ? 18O chronologies. For both carbon and oxygen isotopes, we found significant positive relationships with annual and growing season temperatures and negative relationships with precipitation, again of similar magnitude for all species except for Fraxinus, which contained only minor climatic information. Averaging of all chronologies resulted in an increase in the climatic signal of the mean chronology. The combined ? 18O record reflected decadal-scale temperature variations remarkably well (r = 0.72). However, the relationship between climate and carbon isotopes declined over the last 3 decades of the 20th century, probably related to the steep increase in atmospheric CO 2 concentrations, resulting in strongly diverging ? 13C trends of the different chronologies. Our study indicates that combining chronologies from different species enhances the potential of isotope studies for extending climate reconstructions into areas of temperate climate. Copyright 2008 by the American Geophysical Union.

LWF Classification

Network: LWF, Sites: Bettlachstock, Category: ISI,