. Levels-of-growing-stock cooperative study in douglas-fir : report no. 11--Stampede Creek : a 20-year progress report. . Age (years) Figure 3—Observed trend in top height (H40) compared with height growth curves from King (1966) and Hann and Scrivani (1987). The trend of H40 (mean of all plots) over age is compared in figure 3 with the curves of King (1966) and Hann and Scrivani (1987) having the same height at age 45 Although the site tree definitions used by King and by Hann and Scrivani are not identical with H40, no systematic age-related differences are expected, and past
. Levels-of-growing-stock cooperative study in douglas-fir : report no. 11--Stampede Creek : a 20-year progress report. . Age (years) Figure 3—Observed trend in top height (H40) compared with height growth curves from King (1966) and Hann and Scrivani (1987). The trend of H40 (mean of all plots) over age is compared in figure 3 with the curves of King (1966) and Hann and Scrivani (1987) having the same height at age 45 Although the site tree definitions used by King and by Hann and Scrivani are not identical with H40, no systematic age-related differences are expected, and past experience with the King curves is that substitution of H40 for site trees as defined by King has little effect on estimates. Height growth at Stampede Creek clearly con- forms much more closely with the Hann and Scrivani curves (derived from southwest Oregon data) than with the King curves (western Washington data). Extrapolation of mean crop tree heights (tables 19 and 20) indicates that the next remeasurement will be due in fall 1993. Type of Thinning The LOGS study plan specifies that (1) 80 crop trees per acre will be designated, (2) cutting will be confined to noncrop trees until all noncrop trees are cut, and (3) the average diameter of cut trees shall approximate the average diameter of all trees available for cutting. These specifications have sometimes been misinterpreted as a statement that average d/D (diameter of cut trees/diameter of all trees) is ; which usually would be considered biologically undesirable. In fact, they correspond to crown thinning, with expected d/D considerably less than until all noncrop trees have been removed. Experience at Stampede Creek and Iron Creek suggests that the study plan specifi- cation of d/D = after all noncrop trees have been removed will be realistic and achievable only on plots free from damage because root rot or other damage, when present, determines which trees will be cut. 6. Please note that these images ar
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