FROM THE TREE TO THE FOREST- INVESTIGATING SNOW ACCUMULATION AROUND INDIVIDUAL TREES

ABSTRACT: Estimating the volume of water stored in a snowpack in a montane forest combines spatial measurements of snow depth with average snowpack density. The distribution of snow depth in the forest has been illustrated to be correlated only over short distances (e.g., 8 to 12 m in several Northern Colorado forests), but data are often measured away from trees. The spatial differences about an individual tree are more complex. Trees not only use more water than understory plants, but decrease snowpack accumulation by intercepting snow that is sublimated directly from the canopy or indirectly during redistribution away from the canopy. Variability of snow about a tree is also influenced by canopy offloading (unloading and melt), increases in snowpack metamorphism, and differences in incoming direct versus diffuse solar radiation from the needles, branches, and trunk. Depth and density measurements were taken in the four cardinal directions radially out from seven trees (five Picea engelmanii and two Abies lasiocarpa) across Colorado. These data show that there is directionality in snow depth accumulation. There is a decrease in density approaching each tree, and possible directionality