Climatic effect of atmospheric CO2 doubling on radial tree growth in south eastern France

The climatic effect of a doubling of atmospheric CO₂ on radial growth of trees was studied in ten populations of three species in south eastern France using an Atmospheric General Circulation Model (AGCM) predicting a 3°C increase of mean temperature and a light rise of precipitation. Results are based on empirical growth climate models, involving an Artificial Neural Network (ANN) technique. Only two of the studied populations, on the boundaries of their ecological area, are sensitive to the climatic variations. One is the larch (Larix decidua Mill.) population located at 2300 m on elevation (near the timberline) which shows a radial growth increase. The other is the most southern French Scots pine (Pinus sylvestris L.) population which reacts with a severe growth rate reduction.