Growth potential and drought sensitivity of beech close to the dry distribution limit

Beech at the dry distribution limit in Valais (CH). Picture: Pascale Weber (WSL)

Assessing the impacts of anthropogenic climatic change on the growth and distribution of tree species requires a good knowledge of the climatic, edaphic and synecological controls acting upon each individual species. Regarding European beech (Fagus sylvatica), there is conflicting evidence on the drought response along latitudinal vs. altitudinal gradients.

We aim to answer three questions in this context: (1) What is the functional form of the relationship between drought and growth of beech? (2) Have the growth patterns of beech changed due to recent climatic changes close to the dry distribution limit? (3) Do beech trees of different geographical regions show a different response to site conditions close to the dry distribution limit?

Tree-ring analyses have hardly ever been used to study the influence of soil moisture and nutrient availability on the growth potential and distribution range of individual tree species. In this project, we will use tree-rings for the first time to analyse the relative influence of different site factors – not only climatic but also edaphic – on the growth potential and drought sensitivity of beech at its dry distribution limit.

A combination of dendroecological and soil ecological analyses at three pairs of sites in Switzerland will provide valuable input for assessing the ecophysiology of European beech populations and their sensitivity to changes in climate. Tree growth and sensitivity patterns at field plots close to the dry distribution limit of beech will be compared to mesic plots close-by that experience the same regional climate but better edaphic (moisture and/or nutrients) conditions. Dendroecological methods will be employed to analyse differences in the growth potential and sensitivity of beech with respect to different site factors.

This project is conducted in the framework of COST E52 “Evaluation of Beech Genetic Resources for Sustainable Forestry". In collaboration with Andrea R. Pluess (ETH), we will also analyse the genetic differentiation of beech at dry compared to mesic sites using AFLP markers.

Project team

• Andreas Rigling, WSL
• Harald Bugmann, ETH
• Lorenz Walthert, WSL
• Pascale Weber, WSL

Contact

• Pascale Weber