Browsing by Author "David A. Perry"

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    The Relationship of Maximum Canopy Leaf Area to Forest Growth in Eastern Washington
    (1982) Paul E. Schroeder; Brooks McCandlish; Richard H. Waring; David A. Perry
    Because forests in eastern Washington often exhibit stocking levels significantly below those predicted by standard yield tables, a method was sought to better estimate potential forest-site productivity. Maximum canopy development, expressed as layers of leaves per unit of ground area, or Leaf Area Index (LAI), was more closely related to maximum current stemwood production than was site index alone or a combination of site index, basal area, and age; however, the relationship was not regionally independent. A ratio of annual stemwood production per unit of leaf area, derived from measurements of radial growth and sapwood thickness, was responsive to changes in canopy density within a particular forest but was not sufficiently sensitive to estimate maximum potential LAI.
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    Strip Thinning and Selective Thinning In Douglas-Fir
    (1983-06) Douglas D. McCreary; David A. Perry
    Tree growth was compared on plots that had been strip thinned, selectively thinned, and not thinned in a 35-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stand]. The ratio of basal area increment five years after thinning to basal area increment five years before thinning was larger for all thinning treatments than for the control. However, trees farther than 10 feet from the edges of thinned strips did not respond. Individual tree growth and net stand basal area increment were greater in selectively thinned plots than strip-thinned ones after similar percentages of initial basal area were removed in each. Net stand basal area increment after five years was greater in selectively thinned plots than in strip-thinned ones even where 20 percent more trees had been removed. Nevertheless, lower logging costs and increased silvicultural flexibility may make strip thinning a desirable alternative in some cases.