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Subsurface thermal and hydrological changes between forest and clear-cut sites in the Oregon Cascades
Citation:
Davis, M. G., R. S. WASCHMANN, R. N. Harris, AND D. S. Chapman. Subsurface thermal and hydrological changes between forest and clear-cut sites in the Oregon Cascades. Presented at American Geophysical Union Fall Meeting, San Francisco, CA, December 13 - 17, 2010.
Impact/Purpose:
The Cascades of the US Pacific Northwest are a climatically sensitive area.
Description:
The Cascades of the US Pacific Northwest are a climatically sensitive area. Projections of continued winter warming in this area are expected to induce a switch from a snow-dominated to a rain-dominated winter precipitation regime with a likely impact on subsurface thermal and hydrological regimes. Such changes to the ecosystem may also be linked to changes in land cover, resulting in amplified subsurface temperatures and changing the timing and availability of subsurface water. To monitor changing climatic conditions in this region, the Environmental Protection Agency established pairs of meteorological stations over the Santiam Pass, Cascades Mountains, Oregon, USA, at 5 locations spanning elevations between 500 to 1200 m in the late 1990s. Each location comprises two separate meteorological towers; one under the old-growth coniferous forest canopy and the other in a near by opening or clear-cut. One purpose of the paired stations is to understand the influence of the forest canopy and the developing clear-cut vegetation on the seasonal and annual soil moisture and temperature at each station. We report a comparison of observations between paired stations and a comparison between observations and a land surface model. Preliminary results indicate that open areas have higher air and soil temperatures and receive greater amounts of precipitation and incoming radiation. These conditions are contrasted with the muted conditions under the forest canopy. The results have implications for understanding surface energy exchanges, their impact on the subsurface thermal and hydrological regimes, and possible feedbacks to the climate system as a function of time, space and land cover.