Although many studies have investigated the effects of forest cover on streamflow and runoff, and several have examined the effects of canopy density on snowpack accumulation, the impacts of forest canopy density on spatial patterns of snowmelt input to catchments remain relatively underquantified. We performed an intensive snow depth and density survey during maximum accumulation in a mid-latitude montane environment in northern New Mexico, taking 900 snow depth measurements and excavating six snow pits across a continuum of canopy densities. Snow water equivalent (SWE) data are correlated with forest canopy density (R2 = 0.21, p < 0.0001), with maximum snow accumulation in forests with density between 25 and 40%. Forest edges are shown to be highly influential on patterns of snow depth, with unforested areas shaded by forest to their immediate south holding approximately 25% deeper snow than either large open areas or densely forested areas. This indicates that the combination of canopy influences on throughfall and snowpack shading are key processes underlying snow distribution in the high solar load environments typical of mountainous, mid-latitude areas. We further show that statistical models of snow distribution are improved with the addition of remotely sensed forest canopy information (R2 increased in 10 of 11 cases, deviance lowered in 9 of 11 cases), making these findings broadly relevant for improving estimation of water resources, predicting the ecohydrological implications of vegetation and climate change, and informing integrated forest and water resources management.
Veatch W., Brooks P.D., Gustafson J.R., and Molotch N.P. (2009): Quantifying the effects of forest canopy cover on net snow accumulation at a continental, mid-latitude site. Ecohydrology 2(2): 115-128. DOI: 10.1002/eco.45