. Site index and height growth curves for unmanaged even-aged stands of western hemlock and sitka spruce in southeast Alaska. Western hemlock Alaska; Sitka spruce Alaska; Forest management Alaska; Site index (Forestry) Alaska. Table 6—Regression coefficients for western hemlock from the equation (height — ) = Ci + di (site — ) by 10-year age class, and corrections for mean height after age 50, southeast Alaska Corrected Age at breast hei ght r2 Standard error of estimate Obser- vations Mean height Mean height 2/ Adjusted mean height 2/ Years Feet Number - - Feet - - 10 -0 9758
. Site index and height growth curves for unmanaged even-aged stands of western hemlock and sitka spruce in southeast Alaska. Western hemlock Alaska; Sitka spruce Alaska; Forest management Alaska; Site index (Forestry) Alaska. Table 6—Regression coefficients for western hemlock from the equation (height — ) = Ci + di (site — ) by 10-year age class, and corrections for mean height after age 50, southeast Alaska Corrected Age at breast hei ght r2 Standard error of estimate Obser- vations Mean height Mean height 2/ Adjusted mean height 2/ Years Feet Number - - Feet - - 10 -0 9758 40 23 36 23 36 23 36 20 -2 6963 .4873 .72 40 42 35 42 35 42 35 30 -3 4674 .7075 .88 40 59 90 59 90 59 90 40 -4 2922 .9016 .96 40 75 22 75 22 75 22 50 0 0 40 87 70 87 70 87 70 60 5 5180 .98 30 87 90 99 31 99 31 70 14 3348 .95 20 93 00 107 75 107 75 80 22 4161 .94 20 101 35 116 15 116 15 90 27 9638 .92 18 107 83 123 93 123 93 100 35 6033 .89 17 114 65 130 18 130 18 110 39 1424 .84 14 124 00 136 14 136 14 120 46 1402 .89 10 128 50 142 39 142 08 130 49 2752 .87 10 133 80 148 08 147 18 140 47 0255 .86 8 140 00 152 71 151 58 150 80 9291 .8702 .24 4 157 00 157 83 155 20 ]_/ After age 50, heights were calculated from the equation height = + c-| + d, ( - ) to adjust for decreasing numbers of observations and changing mean site index. 2/ Calculated heights for ages 120 years and older resulted in a poor fit of the combined equation so they were adjusted downward to give the height and site curves a more realistic fit; otherwise, they would turn upward after age 0 20 40 60 80 100 120 140 160 Age at breast height (years) Figure 7—Mean height of sectioned western hemlock as a function of age at breast height for each 10-year age class. Plotted points are actual mean heights minus feet. Solid line is expressed by the
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