[Impact of the climatic scenario of global warming on the growth of trees]

The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied for 24 populations of five tree species in the French Alps and the French Mediterranean area. The Arpege AGCM, which predicts a 3 degrees C increase in mean temperature and a light increase of precipitation, is used to estimate the climatic perturbation. The method is based on the integration of estimated climate in an empirical tree-ring to climate model, involving artificial neural networks. Only a few populations are sensitive to the climatic change; all are located on the boundaries of their ecological area and can be divided in two groups. The first one is composed of high altitude populations which show a growth increase induced by the warmer climate during the growing season. The second one, composed of a single Mediterranean Scots pine population, reacts with a severe growth reduction induced by the stronger water stress in summer.

Wieso sterben die Waldföhren im «TeIwald» bei Visp? Eine Zusammenfassung bisheriger Studien und eine dendroökologische Untersuchung | What is the Cause of the High Mortality Rates of the Scots Pines in the «Telwald» near Visp (Switzerland)? A Summary of Previous Studies and a Dendroecological Study

The processes involved in the phase of mortality affecting Scots pine (Pinus sylvestris L.) observed since the beginning of this century in the canton of Valais (Switzerland) are related to the vegetation history, the ecology and stand dynamics as well as the pollution history.