Climate change is leading to drier conditions in Valais. For around two decades now, many Scots pines in the canton have been dying, in some cases over large areas. The Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) is conducting an irrigation experiment to investigate the growth of Scots pines in the Pfyn Forest. Since 2003, it has been irrigating a number of plots within the forest to illustrate the dependency of pine growth on an adequate water supply.