Description succincte
(Anglais)
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The goal of this project is to establish a drought resistance ranking for selected tree species in Switzerland. The ranking will be derived from past reactions of these species to droughts, in particular those of 1976 and 2003. We will use 5-10 large 30-100 years old afforestations with endemic and exotic tree species as field experiments. The sites will be selected on gradients from very dry to moderately dry regions. Tree response to past droughts will be assessed using dendro-ecological methods. On each site, we will core about 15 canopy trees of 5-10 species. In data analysis, we focus on: i) species- and/or provenance-specific reactions of ring width to drought periods and subsequent recovery (intervention-detection analysis); ii) growth variability as proxy for growth elasticity, and iii) additional evidence for drought-related mortality. Apart from this tree ring-level study, we focus, in a small subset of the sites and species, on cell characteristics such as cell size to gain a better understanding of reaction patterns. The results should enable us to identify species-specific reactions to drought stress, and to establish a ranking of drought stress resistance for the species studied, as a basis for the establishment of a revised tree species portfolio. The novelty of the study is the comparison of endemic and exotic tree species growing on the same site, and the focus on drought stress response including recovery. The study will be conducted as a PhD thesis.
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Partenaires et organisations internationales
(Anglais)
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AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GR, HR, HU, IE, IT, LT, LV, NL, NO, PL, PT, RS, SE, SI, SK, UK
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Résumé des résultats (Abstract)
(Anglais)
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The goal of this project is to establish a drought resistance ranking for selected tree species in Switzerland. The ranking will be derived from past reactions of these species to droughts, in particular those of 1976 and 2003. We will use 5-10 large 60-100 years old afforestations with endemic and exotic tree species as field experiments. The sites will be selected on gradients from very dry to moderately dry regions. In February 2010, the PhD student (Mathieu Lévesque) started his work. Under the supervision of Britta Eilmann (Postdoc at WSL), Andreas Rigling and Peter Brang, he developed his research plan which was has been submitted to the supervising professor (Harald Bugmann, ETH Zurich) in early 2011. The major achievements in 2010 were: 1) M. Lévesque got acquainted with the topic of his PhD. 2) The methods to be used in this study were refined and defined in the PhD research plan, includ-ing the sampling design, the dendroecological approaches and the potential papers. 3) >20 potential sites for coring were visited using a data base of exotic plantations in Switzerland. Suitable sites were retained. To cover a large site gradient, one site in Aosta valley and another one in Vinschgau (both Italy) were selected. 4) Coring started mainly in one site in Switzerland. Technical difficulties (broken equipment) in cor-ing large Douglas fir trees were encountered, and a solution seems now at hand. 5) Several cores were prepared for measurements, and first measurements done. 6) A proposal for an additional study was submitted to the Research Programm Forests and Climate Change of FOEN and WSL. In February 2011, this study was funded.
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