Influence of micro-site conditions and environmental gradients on tree-ring based climate reconstructions

• Main Author: Düthorn, Elisabeth
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Johannes Gutenberg-Universität Mainz 2015
• Subjects: ddc:500; Fennoscandia
• Online Access: https://openscience.ub.uni-mainz.de/handle/20.500.12030/3626; https://hdl.handle.net/20.500.12030/3626; https://doi.org/10.25358/openscience-3624

Tree-ring chronologies are a powerful natural archive to reconstruct summer temperature variations of the late Holocene with an annual resolution. To develop these long-term proxy records tree-ring series are commonly extended back in time by combining samples from living trees with relict dead material preserved onshore or in lakes. Former studies showed that low frequency variations in such reconstructions can be biased if the relict and recent material is from different origins. A detailed analysis of the influence of various ecological (micro-) habitats representing the recent part is required to estimate potential errors in temperature estimates. The application of collective detrending methods, that comprise absolute growth rates, can produce errors in climate reconstructions and results in an underestimation of past temperatures. The appearance of these kind of micro-site effects is a wide-spread phenomenon that takes place all over Fennoscandia. Future research in this key region for dendroclimatology should take this issue into account. Especially the higher climate response at the lakeshore site is interesting to achieve smaller uncertainties when a tree-ring series is transformed to temperature anomalies. For new composite chronologies the main aim should be to minimize potential biases and this includes also micro-site effects. Jahrringchronologien sind ein einzigartiges natürliches Archiv. Mit ihrer Hilfe lassen sich Temperaturvariationen der letzten tausend Jahre rekonstruieren. Da Bäume eine begrenzte Lebenszeit haben, müssen die Chronologien von lebenden Bäumen mit Totholzproben verknüpft werden. Vorherige Studien zeigen, dass die Herkunft und die Vergleichbarkeit des Materials von großer Bedeutung sind. Um festzustellen, ob verschiedene ökologische Milieus eine Auswirkung auf Klimarekonstruktionen haben, bedarf es einer strukturierten und detaillierten Analyse rezenten Materials. Es zeigt sich, dass kollektive Standardisierungsmethoden, die die Wachstumsraten mit einbeziehen, einen Fehler des ...