Relation of forests to snow

The effects of forest cover on the accumulation and melting of snow are discussed in relation to water conservation on the basis of surveys made in the U.S. at various periods dating back to 1911. Studies in various regions on snowfall interception by trees of varying crown density, the reduction of wind speed and snow accumulation in openings, and the reduction of solar radiation intensity and accompanying retardation of melt are summarized, and representative data are tabulated. Snow accumulation was found greatest in small openings without crown cover in forests (15.6% more than in the open) and least under a dense cover of trees (32.5% less than in the open). Melting was most rapid in burned areas, and slowest under virgin all-age red fir stand. There was a linear decrease of melting on clear days with increased crown density, amounting to 3 in./day with no crown cover and 2 in./day under 70% crown cover. Differences in kind, size, and density of forest or other vegetation are also reflected in the accumulation and melting of snow. The optimum forest with respect to water conservation appears to be one which is fairly open with interspersed glades.