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B320: Combining dendroecology and wood anatomy for dating Golden Eagle eyries in the Swiss Alps (Lead Supervisor: Ulf Büntgen, Geography)

Supervisors: Ulf Büntgen (Geography) and Paul Krusic (Stockholm University)

Importance of the area of research:

The Golden Eagle (Aquila chrysaetos L.) is among the most famous raptor species in the European Alps. Long lasting habitats in the eastern Swiss Alps and the species’ habit of re-using historical eyries have resulted in a sizable number of big wooden constructions composed of possibly very old wood. The maximum ages of eyries, which usually consist of various construction phases, remain in most cases unknown. Since many of the eyries are located near the upper treeline, larch (Larix decidua) and pine (Pinus cembra) branches used for construction may contain up to 100 annual growth rings. These rings will be cross-dated and measured by careful wood anatomical thin sectioning and double staining. Dendrochronological dating of the eyries can potentially provide evidence on long-term variations in eagle population density, which may be further analysed in the light of environmental factors, including climate change.

Project Summary:

This project will, for the first time, combine dendroecological and wood anatomical techniques to develop branch chronologies from living conifers and old material from eagle eyries in Switzerland. Annual dating of different construction phases of several eyries will ideally help providing a long-term context of past changes in the predator’s population density. Due to their setting near the upper treeline, both the new branch data but also the birds’ behaviour are expected to be temperature sensitive. The project will thus improve knowledge on how long-term climate variability may have influenced the size and dynamic of Golden Eagle populations in the Swiss Alps.

What the student will do:

You will perform dendro-fieldwork in the eastern Swiss Alps. The intensive sampling of branch material at different construction layers of several (up to two meter-high) Golden Eagle eyries will be supported by professional climbers and wildlife biologists. You will also collect reference material from living trees at numerous high-elevation sites in the same region. You will combine dendroecological and wood anatomical techniques to develop the first network of branch chronologies for large parts of the eastern Swiss Alps. You will further use the precise dating of historical construction phases of the eyries to gain insight into long-term changes in the species’ population density. Knowledge of the construction and utilization ages of various eagle eyries will ultimately be compared against high-resolution climate reconstructions to explore possible effects of Little Ice Age cooling before around the mid-19th century and of the subsequent anthropogenic warming on the population dynamics of one of the most fascinating predators of the Alpine arc.

Please contact the directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Gärtner, H., Cherubini, P., Fonti, P., von Arx, G., Schneider, L., Nievergelt, D., Verstege, A., Bast, A., Schweingruber, F.H. & Büntgen, U. 2015. Technical challenges in tree-ring research including wood anatomy and dendroecology. Journal of Visualized Experiments doi: 10.3791/52337 (e52337)

Büntgen, U., Jenny, H., Liebhold, A., Mysterud, A., Egli, S., Nievergelt, D., Stenseth, N.C. & Bollmann, K. 2014. European springtime temperature synchronizes ibex horn growth across the eastern Swiss Alps. Ecology Letters 17: 303-313

Büntgen, U., Psomas, A. & Schweingruber, F.H. 2014. Introducing wood anatomical and dendrochronological aspects of herbaceous plants: applications of the Xylem Database to vegetation science. Journal of Vegetation Science 25: 967-977

Schweingruber, F.H. & Büntgen, U. 2013. What is ‘wood’ – An anatomical re-definition. Dendrochronologia 31: 187-191

Follow this link to find out about applying for this project

 

 

 

 

 

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