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• 1. [Article] Wood density and fiber length in young populus stems: relation to clone, age, growth rate, and pruning

  Cross-sectional disks were cut at two stem heights (1.5 m and 3.0 m) from 9-year-old trees of three Populus clones grown in an intensively-cultured plantation in western Washington. At age 1.5 years, when ...

  Citation × Citation Citation Abstract Copy Title: Wood density and fiber length in young populus stems: relation to clone, age, growth rate, and pruning Author: Gartner, B. L., Singleton, R., Harrington, C. A., DeBell, D. S. Cross-sectional disks were cut at two stem heights (1.5 m and 3.0 m) from 9-year-old trees of three Populus clones grown in an intensively-cultured plantation in western Washington. At age 1.5 years, when the trees averaged 3.4 m tall, half of the trees were pruned by removing all branches below 1.8 m. Ring width, wood density, and fiber length were measured for each ring. Pruning had no effect on mean ring width or wood properties, averaged over the entire disk or on rings produced during the 2nd through the 4th years. Averaged over all trees, wood density of the 1.5 m sample was 0.37 g cm-3 during the first 3 years, decreased somewhat at age 4 or 5, and then increased to an average of 0.45 g cm-3 at age 9. Fiber length increased from 0.57 mm at age 1 to nearly 1.0 mm at age 9. Averaged over all disks at 1.5 m, clones differed significantly in ring width, wood density, and fiber length. Mean values for the two wood properties at 3.0 m were slightly lower than those at 1.5 m and did not differ significantly among clones. Within clone correlations between ring width and wood density or fiber length or between wood properties were low, and generally non significant or inconsistent. Title: Wood density and fiber length in young populus stems: relation to clone, age, growth rate, and pruning Author: Gartner, B. L., Singleton, R., Harrington, C. A., DeBell, D. S. Cross-sectional disks were cut at two stem heights (1.5 m and 3.0 m) from 9-year-old trees of three Populus clones grown in an intensively-cultured plantation in western Washington. At age 1.5 years, when the trees averaged 3.4 m tall, half of the trees were pruned by removing all branches below 1.8 m. Ring width, wood density, and fiber length were measured for each ring. Pruning had no effect on mean ring width or wood properties, averaged over the entire disk or on rings produced during the 2nd through the 4th years. Averaged over all trees, wood density of the 1.5 m sample was 0.37 g cm-3 during the first 3 years, decreased somewhat at age 4 or 5, and then increased to an average of 0.45 g cm-3 at age 9. Fiber length increased from 0.57 mm at age 1 to nearly 1.0 mm at age 9. Averaged over all disks at 1.5 m, clones differed significantly in ring width, wood density, and fiber length. Mean values for the two wood properties at 3.0 m were slightly lower than those at 1.5 m and did not differ significantly among clones. Within clone correlations between ring width and wood density or fiber length or between wood properties were low, and generally non significant or inconsistent. Close

• 2. [Article] Effects of pruning on wood density and tracheid length in young Douglas-fir

  To study whether pruning young Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) hastens the transition from juvenile to mature wood, we investigated the effects on wood properties in an ...

  Citation × Citation Citation Abstract Copy Title: Effects of pruning on wood density and tracheid length in young Douglas-fir Author: Gartner, B. L., Robbins, J. M., Newton, M. To study whether pruning young Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) hastens the transition from juvenile to mature wood, we investigated the effects on wood properties in an intensively managed young plantation in the Coast Range of Oregon. Ten years after trees were pruned to a fixed height (3.4 or 5.5 m), we investigated the effects on wood density (in 12 trees per pruning treatment, two or three treatments per age class, three age classes, and two heights for a total of 168 cores) and tracheid length (in four trees per treatment, one height and age class only, for 12 trees total). The trees were 13, 16, and 18 years old when pruned in 1988. Removal of 50% of the live crown in young trees caused a small one-year decline in growth ring width at breast height, but removal of 30% of the live crown did not. In partial contrast, pruning caused no detectable effect on wood density at breast height, presumably because the branches were in the lower crown, and were not contributing much to the growth of the bole. Pruning caused a small increase in wood density at the upper height (5.3 m) in the youngest age class (for which this 5.5 m pruning would be removing vigorous live branches at this height) but not in the medium age class (for which the pruning would be removing lower live crown at this height) or in the oldest age class (for which there would have been no live branches at 5.5-m). Pruning the youngest trees caused a 3–4 year increase in tracheid length at breast height. In summary, pruning had very small or no effect on growth ring width, density, or tracheid length; but the effects that it had were the ones expected if pruning accelerated the transition from juvenile to mature wood. The larger benefit of pruning, especially if done early in rotation, is to shorten branch healing time and provide for a longer period of clear wood production. Title: Effects of pruning on wood density and tracheid length in young Douglas-fir Author: Gartner, B. L., Robbins, J. M., Newton, M. To study whether pruning young Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) hastens the transition from juvenile to mature wood, we investigated the effects on wood properties in an intensively managed young plantation in the Coast Range of Oregon. Ten years after trees were pruned to a fixed height (3.4 or 5.5 m), we investigated the effects on wood density (in 12 trees per pruning treatment, two or three treatments per age class, three age classes, and two heights for a total of 168 cores) and tracheid length (in four trees per treatment, one height and age class only, for 12 trees total). The trees were 13, 16, and 18 years old when pruned in 1988. Removal of 50% of the live crown in young trees caused a small one-year decline in growth ring width at breast height, but removal of 30% of the live crown did not. In partial contrast, pruning caused no detectable effect on wood density at breast height, presumably because the branches were in the lower crown, and were not contributing much to the growth of the bole. Pruning caused a small increase in wood density at the upper height (5.3 m) in the youngest age class (for which this 5.5 m pruning would be removing vigorous live branches at this height) but not in the medium age class (for which the pruning would be removing lower live crown at this height) or in the oldest age class (for which there would have been no live branches at 5.5-m). Pruning the youngest trees caused a 3–4 year increase in tracheid length at breast height. In summary, pruning had very small or no effect on growth ring width, density, or tracheid length; but the effects that it had were the ones expected if pruning accelerated the transition from juvenile to mature wood. The larger benefit of pruning, especially if done early in rotation, is to shorten branch healing time and provide for a longer period of clear wood production. Close

• 3. [Article] Effects of live crown on vertical patterns of wood density and growth in Douglas-fir

  It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), ...

  Citation × Citation Citation Abstract Copy Title: Effects of live crown on vertical patterns of wood density and growth in Douglas-fir Author: Gartner, B. L., Johnson, G. R., North, E. M., Singleton, R. It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), to develop silvicultural regimes that control the relative production of the two types of wood. Foresters commonly assume the bole of softwoods produces juvenile wood within the crown and mature wood below. We tested that assumption by comparing growth ring areas and widths and wood density components of the outer three growth rings in disks sampled from different vertical positions of 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The 18 trees were sampled from one site and had a wide range of heights to live crown. Most of the variance (63–93%) in wood characteristics (growth ring area: total, earlywood, latewood; growth ring width: total, earlywood, latewood; latewood proportion: by area, width; and ring density: total, earlywood, latewood) was due to within-tree differences (related to age of the disk). Stepwise regression analysis gave us equations to estimate wood characteristics, after which we analyzed the residuals with a linear model that included whether a disk was within or below the crown (defined as the lowest node on the stem with less than three live branches). After adjusting for tree and disk position, only 2–10% of the residual variation was associated with whether the disk was in or out of the live crown. There were no statistically significant differences at p = 0.05 between a given disk (by node number) in versus out of the crown for any of the factors studied. Moreover, the wood density characteristics were not statistically significant at p = 0.30. This research suggests that there was no effect of the crown position on the transition from juvenile to mature wood as judged by wood density. Therefore, we found no evidence to support the concept that tree spacing and live-branch pruning have a significant effect on the cambial age of transition from juvenile to mature wood in Douglas-fir trees of this age. Title: Effects of live crown on vertical patterns of wood density and growth in Douglas-fir Author: Gartner, B. L., Johnson, G. R., North, E. M., Singleton, R. It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), to develop silvicultural regimes that control the relative production of the two types of wood. Foresters commonly assume the bole of softwoods produces juvenile wood within the crown and mature wood below. We tested that assumption by comparing growth ring areas and widths and wood density components of the outer three growth rings in disks sampled from different vertical positions of 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The 18 trees were sampled from one site and had a wide range of heights to live crown. Most of the variance (63–93%) in wood characteristics (growth ring area: total, earlywood, latewood; growth ring width: total, earlywood, latewood; latewood proportion: by area, width; and ring density: total, earlywood, latewood) was due to within-tree differences (related to age of the disk). Stepwise regression analysis gave us equations to estimate wood characteristics, after which we analyzed the residuals with a linear model that included whether a disk was within or below the crown (defined as the lowest node on the stem with less than three live branches). After adjusting for tree and disk position, only 2–10% of the residual variation was associated with whether the disk was in or out of the live crown. There were no statistically significant differences at p = 0.05 between a given disk (by node number) in versus out of the crown for any of the factors studied. Moreover, the wood density characteristics were not statistically significant at p = 0.30. This research suggests that there was no effect of the crown position on the transition from juvenile to mature wood as judged by wood density. Therefore, we found no evidence to support the concept that tree spacing and live-branch pruning have a significant effect on the cambial age of transition from juvenile to mature wood in Douglas-fir trees of this age. Close