Missoulian: Only one in ten raindrops that fall on a pine forest reaches the ground. The rest are appropriated by the forest canopy—provided the trees are alive and healthy. In the Pacific Northwest, the mountain pine beetle has killed trees that covered tens of thousands of square kilometers. To assess the impact of the devastation on the region’s water cycle, University of Alberta professor Uldis Silins and his collaborators are conducting an extensive field experiment in the Canadian Rockies.