Field Study Valais

Effect of soil texture on transpiration losses during drought

The Valais is the driest region of Switzerland with an average yearly precipitation of 600 mm. In the coming decades, due to climate change, periods of drought will increase throughout Switzerland. The Valais is therefore strategic to study trees in a drought-prone area and to gain insights for the future of Swiss forests. Our aim is to understand the mechanisms controlling water use regulation of trees. Our hypothesis is that the closure of stomata is primarily triggered by a loss of soil hydraulic conductivity. We are investigating this hypothesis on field sites with contrasting soil textures. By combining combine measurements of soil and plant water status, atmospheric conditions, transpiration rate and geophysical methods, we aim to show the profound link between tree water use and soil properties. Potentially, this will help to better predict areas at risk of droughts in Switzerland under a changing climate.