The timing of snow disappearance is an important control of the amount and timing of water available for forest ecosystems and downstream communities. In forested areas, trees intercept snowfall which decreases snow accumulation, but they also shade the snowpack from the sun and reduce wind, which lengthens snow retention. Warm trees also emit thermal radiation that can melt the snowpack near the canopy. Competition among these factors causes different snow disappearance timing in open areas versus under tree canopy. We use light detection and ranging (lidar) measurements to quantify snow presence or absence in the open and below the forest canopy. The results show that snow disappears earlier under dense forest canopy than in open areas at warmer sites, especially on south-facing slopes that receive more sunlight. In contrast, colder sites tend to retain snow longer under a tree canopy than open areas, especially on north-facing slopes. However, lower elevations of colder sites can behave more like warmer sites by retaining snow longer in open areas. This unique multi-site snow dataset suggests that tree canopy removal would have greater benefit for retaining snow longer at warm sites than at cold sites, although additional refinement is needed.
