Wind in the Subarctic Forest

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  • a Department of Geography, University of Toronto, Toronto, Canada M5S 1A1
  • | b University of Maryland, College Park 20742
  • | c British Columbia Ministry of the Environment, Victoria, Canada, V8V IX4
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Abstract

In the subarctic region of central Labrador wind speeds were measured at 2 m height in open lichen woodlands of various stand densities and were related to standard winds recorded at the same level on the local airport site. The resulting reduction in wind speeds are shown to be closely related to stand parameter h* which is a function of average tree height, stand density and shrub cover; variables that can easily be obtained from airphotos or from direct ground surveys. The equation giving the ratio of wind in the woodland u(s)to that measured at the air field u(s) is u(s)=u(s)(1+βh*)−2 with β=1.16 for s=2, and s=2.0 m. The equation seems applicable to various types of stands that do not streamline in wind, ranging from open lichen cover without trees, to a dense but leafless deciduous winter hardwood forest stand. For the typical and geographically widespread open lichen woodland of the subarctic, h* was related to the usual silvicultural measure of trunk diameter at breast height (DBH) offering a useful short cut in possible ground surveys.

Abstract

In the subarctic region of central Labrador wind speeds were measured at 2 m height in open lichen woodlands of various stand densities and were related to standard winds recorded at the same level on the local airport site. The resulting reduction in wind speeds are shown to be closely related to stand parameter h* which is a function of average tree height, stand density and shrub cover; variables that can easily be obtained from airphotos or from direct ground surveys. The equation giving the ratio of wind in the woodland u(s)to that measured at the air field u(s) is u(s)=u(s)(1+βh*)−2 with β=1.16 for s=2, and s=2.0 m. The equation seems applicable to various types of stands that do not streamline in wind, ranging from open lichen cover without trees, to a dense but leafless deciduous winter hardwood forest stand. For the typical and geographically widespread open lichen woodland of the subarctic, h* was related to the usual silvicultural measure of trunk diameter at breast height (DBH) offering a useful short cut in possible ground surveys.

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