Abstract |
A water budget was determined for pure, fully stocked stands of Douglas-fir and Oregon white oak. Plots were irrigated one summer to measure water loss when water was freely available--an attempt to simulate potential conditions. A plastic roof was constructed under the canopy of each of the stands and a plastic barrier installed in the soil to permit early spring and winter measurements for one year. Measurements consisted of gross precipitation in openings, throughfall, and soil-water change. Interception storage was determined to be .02 inches for oak in a leafless condition, .10 inches when in leaf, .13 inches for Douglas-fir in winter, and .20 inches in summer. The disposition of average annual precipitation (1965 and 1966) to interception loss is 21 percent for Douglas-fir and 7.5 percent for Oregon white oak, eight and three inches, respectively. Computed hydraulic gradients indicate downward water movement in the oak soil profile for a longer period in the spring months. (WRSIC abstract) |