Quantifying the Influence of Vegetation on Net Snow Accumulation Across Elevations, Aspects and During Years With High and Low Snowfall

ABSTRACT Seasonal snowmelt from forested mountain catchments is the primary water source for both people and ecosystems in the western United States. As changes in climate and vegetation alter relationships between snow accumulation and water availability, quantifying the influence of ecosystem structure on snow water resources is a critical challenge. To address this knowledge gap, we performed 2 years of distributed snow surveys to quantify how vegetation structure, topography and winter conditions interact to control net snow accumulation. The ratio of net snow water equivalence (SWE) at peak accumulation to winter snowfall (SWE:P) was 0.85 (range 0.67–1.03). This variability in SWE:P was associated with seven distinct vegetation environments that differentially influenced snow accumulation across all sites and years. Greatest snow accumulation was found in open areas immediately north of forests (SWE:P = 1.03 ± 0.05), followed by small gaps in conifer forests (SWE:P = 0.95 ± 0.07), small gaps in aspen forests (SWE:P = 0.88 ± 0.08), nonshaded open areas (SWE:P = 0.88 ± 0.05), under aspen canopies (SWE:P = 0.81 ± 0.04), under coniferous canopies (SWE:P = 0.76 ± 0.04) and lowest in open areas in south‐facing forest edges (SWE:P = 0.67 ± 0.07). These spatial patterns in net SWE input were more pronounced in nontopographically shaded environments, suggesting that the influence of vegetation on local hydroclimate and net snow accumulation was greater in areas with higher solar radiation input. The consistency of these patterns across high and low elevations and during low‐ and high‐snow years suggests that forest structure can be used to distribute spatial patterns in snow water input in both undisturbed forests and in response to forest management.