Turbulence Near the Forest Floor of an Old-Growth Douglas-Fir Stand on a South-Facing Slope
Abstract:This paper reports the results of the analysis of measured turbulence regimes near the forest floor in an old-growth Douglas-fir stand on a south-facing slope in northern Vancouver Island, Canada. Primary instrumentation included one eddy correlation unit, which consisted of a three-dimensional sonic anemometer, a krypton hygrometer and a fine wire thermocouple, and four home-made hot wire anemometers. The general features of the turbulence regimes near the forest floor within this stand were similar to those observed previously in other stands with an open trunk space. The high value of the ratio of the wind speed inside the stand to that outside (0.42) suggested the existence of a secondary maximum in the stand wind profile. The wind speed near the forest floor was approximately a logarithmic function of height with an effective roughness length of 0.012 m. The average turbulence intensity was 0.86. Power spectra for the streamwise and lateral velocity components exhibited a bimodal distribution in contrast with a unimodal distribution for the spectrum of the vertical component. Near the forest floor, latent heat and sensible heat generally flowed down humidity and temperature gradients, respectively. Some unique features were also observed, namely the suppression of the vertical velocity variance by the moderate to strong temperature inversion in the daytime and the occurrence of a very small eddy diffusivity for sensible heat flux. FOR. SCI. 39(2):211-230.
Document Type: Journal Article
Affiliations: Professor in the Department of Soil Science, University of British Columbia, Vancouver, B.C., Canada, V6T 1Z4
Publication date: May 1, 1993
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- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
Forest Science is published bimonthly in February, April, June, August, October, and December.
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