Pfynwald - Switzerland

In Switzerland, the temperature increase from the end of the 20th century to the beginning of the 21st was more than double the global average. Climate models suggest that the 21st century will see a further rise in temperatures. In conjunction with the heat-related increase in evaporation and more frequent heat waves, it is safe to assume that the water supply available to trees is steadily deteriorating and that heavy rainfall is to be increasingly expected in the summer months. This rainfall will increase surface water runoff and will not seep into the soil, meaning that plants will increasingly suffer from stress caused by drought. Consequently, the vitality and growth of the pines will fall. In the long term, drought may lead to an increasing number of tree deaths and cause vegetation areas to shift. This is particularly true for the forest ecosystem of inner-alpine dry valleys such as those in Valais (Rigling et al. 2013). For a better understanding of the medium-to long-term effects of drought periods on forests, results from experiments in dry areas with an extended series of in situ measurements are required.