. Growth of ponderosa pine poles thinned to different stocking levels in central Oregon. Ponderosa pine Oregon; Ponderosa pine Oregon Spacing. 03 200 - i— pe 180 - en 160 - E 0) i— 140 - o c "S 0 120 - o E (J 100 - 3 z o 3 > O 80 - TO 3 60 - C C n 40 - o T3 20 - 0) a 5-year growth period \\ First | Second 0 Third 6 11 1f 30 Gross -Net 3 8 16 60 2 12 15 5 7 10 4 9 13 Plot number SO 100 120 Growing-stock level 1 14 17 150 Figure 5.—Periodic, annual net- and gross- volume increment of ponderosa pine poles thinned to six different growing-stock levels on a productive site in central Oregon
. Growth of ponderosa pine poles thinned to different stocking levels in central Oregon. Ponderosa pine Oregon; Ponderosa pine Oregon Spacing. 03 200 - i— pe 180 - en 160 - E 0) i— 140 - o c "S 0 120 - o E (J 100 - 3 z o 3 > O 80 - TO 3 60 - C C n 40 - o T3 20 - 0) a 5-year growth period \\ First | Second 0 Third 6 11 1f 30 Gross -Net 3 8 16 60 2 12 15 5 7 10 4 9 13 Plot number SO 100 120 Growing-stock level 1 14 17 150 Figure 5.—Periodic, annual net- and gross- volume increment of ponderosa pine poles thinned to six different growing-stock levels on a productive site in central Oregon. o E 3 O c (0 o O <D Q. 180 170 160 h 140 120 100 80 60 40 20. Decade of growth after initial thinning y = + R2 = 5-year period after second thinning y = + Loge x Ft* = 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 Initial basal area (square feet) Figure 6.—Periodic, annual gross-volume increment during the decade after initial thinning and during the 5 years after the second thinning. suggestion of leveling off in volume production at the higher levels. This may simply reflect having to cut relatively more trees at the higher GSL's to accom- modate the required thinning to the desired growing-stock level after 10 years of growth. Board-foot volume and volume growth are presented (tables 1, 2), but have limited meaning relative to GSL because many trees at the higher GSL's are growing into board-foot sizes. The small- est tree considered merchantable was 9 inches , capable of producing an 8-foot log with a 5-inch top inside bark at the small end, a realistic utilization on many operations in eastern Oregon. Total Yield and Tree Size Although drawing conclusions about long-term yield would be premature, the outlook is favorable. Total yield, including the second thinning only, 15 years after initial thinning, increased with higher growing-stock levels (fig. 7). The highest GSL yielded about 5,000 cubic feet of w
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