The Influence of a Heterogeneous Mixed-Conifer Canopy on Snow Accumulation and Melt

The patterns of snow accumulation and ablation have been linked to the timing and quantity of available water in the semi-arid forested mountain watersheds. Forest patterns are often used as surrogates for processes where we expect that spatially recognizable structures give rise to ecohydrological processes. Forest canopies exhibit heterogeneity manifested as a mosaic of differing species, spatial arrangements, and canopy densities that differentially intercept precipitation and absorb or reflect radiation; thereby controlling the processes of snow accumulation and ablation. In this study we examined how heterogeneous canopy structure influenced the spatial variability of snow water equivalent (SWE) and disappearance date. High resolution, empirical snow measurements were collected at peak accumulation and monitored regularly throughout the melt season on two, 4.48 ha, fully georeferenced, mixed-conifer plots in western Montana. In 2014, peak accumulation occurred on March 18 and snow lasted 48 days with peak snow water equivalent ranging from 0 -17.9 cm. Percent canopy cover ranged from 0-86%. Higher canopy density areas had lower snow accumulation and earlier disappearance dates. By linking canopy patterns to specific snow processes, we will be able to improve process based models to provide more accurate predictions of water availability. Model predictions can be scaled up to management relevant scales and provide managers with empirical management recommendations for optimizing water resources given climate change and increased drought.

Presentation in PDF - Spatial Variation of Snow Water Equivalent and Snow Disappearance Date Beneath a Mixed-Conifer Canopy