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• 1. [Article] Does photosynthetic bark have a role in the production of core vs. outer wood?

  This paper hypothesizes a correlation in some species between the cambial age of transition from core (juvenile) to outer (mature) wood and the cambial age of transition from photosynthetic to non-photosynthetic ...

  Citation × Citation Citation Abstract Copy Title: Does photosynthetic bark have a role in the production of core vs. outer wood? Author: Gartner, B. L. This paper hypothesizes a correlation in some species between the cambial age of transition from core (juvenile) to outer (mature) wood and the cambial age of transition from photosynthetic to non-photosynthetic bark. Secondly, this paper hypothesizes that the relationship is causal: a signal produced in relation to the photosynthetic bark affects wood development a few millimeters away. It is further hypothesized that the photosynthetic periderm is replaced by a non-photosynthetic one at light levels below its light compensation point. In Tsuga heterophylla and Pseudotsuga menziesii var. menziesii, the cambial age at which the first periderm dies (the base of photosynthetic bark) ranges from 16 to 33 and 12 to 43 years, respectively, for four Oregon Coast Range populations. These values are in the same range as the cambial ages of transition from core to outer wood, as shown by literature values and data reported here on tracheid length in T. heterophylla. In both species, the cambial age at the base of the live crown is not coincident with, nor consistently higher or lower than, the height of the lowest photosynthetic bark. Data presented here are consistent with the photosynthetic bark hypothesis of formation of core wood, but manipulative studies are needed to further explore the relationship. Title: Does photosynthetic bark have a role in the production of core vs. outer wood? Author: Gartner, B. L. This paper hypothesizes a correlation in some species between the cambial age of transition from core (juvenile) to outer (mature) wood and the cambial age of transition from photosynthetic to non-photosynthetic bark. Secondly, this paper hypothesizes that the relationship is causal: a signal produced in relation to the photosynthetic bark affects wood development a few millimeters away. It is further hypothesized that the photosynthetic periderm is replaced by a non-photosynthetic one at light levels below its light compensation point. In Tsuga heterophylla and Pseudotsuga menziesii var. menziesii, the cambial age at which the first periderm dies (the base of photosynthetic bark) ranges from 16 to 33 and 12 to 43 years, respectively, for four Oregon Coast Range populations. These values are in the same range as the cambial ages of transition from core to outer wood, as shown by literature values and data reported here on tracheid length in T. heterophylla. In both species, the cambial age at the base of the live crown is not coincident with, nor consistently higher or lower than, the height of the lowest photosynthetic bark. Data presented here are consistent with the photosynthetic bark hypothesis of formation of core wood, but manipulative studies are needed to further explore the relationship. 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

• 4. [Article] Fiber length in young hybrid Populus stems grown at extremely different rates

  Length of libriform fibers was measured in rings 2 7 at breast height in 7-year-old hybrid poplar stems from two clones (11-11, a Populus trichocarpa Torr. & Gray ´ P. deltoides Bartr. ex Marsh. hybrid; ...

  Citation × Citation Citation Abstract Copy Title: Fiber length in young hybrid Populus stems grown at extremely different rates Author: Gartner, B. L., DeBell, J. D., DeBell, D. S. Length of libriform fibers was measured in rings 2 7 at breast height in 7-year-old hybrid poplar stems from two clones (11-11, a Populus trichocarpa Torr. & Gray ´ P. deltoides Bartr. ex Marsh. hybrid; and D-01, of unknown taxonomic identity) grown in a controlled test of three spacings (0.5, 1.0, and 2.0 m) on an irrigated and fertilized site in western Washington. In each clone, samples included a very wide range of cambial growth rates, with ring widths from 1 to 19 mm. Growth rate, expressed in several ways, had no consistent effect on fiber length within rings of the same age for rings 2 6. For ring 7, however, there were positive correlations between most growth rate measures and fiber length. Whole-disk fiber length increased with overall growth rate as measured by stem diameter; this apparent anomaly is caused by the fact that fast-growing trees have more of their basal area concentrated in rings further from the pith than do slower growing trees, and these rings have longer fibers compared with rings closer to the pith. Title: Fiber length in young hybrid Populus stems grown at extremely different rates Author: Gartner, B. L., DeBell, J. D., DeBell, D. S. Length of libriform fibers was measured in rings 2 7 at breast height in 7-year-old hybrid poplar stems from two clones (11-11, a Populus trichocarpa Torr. & Gray ´ P. deltoides Bartr. ex Marsh. hybrid; and D-01, of unknown taxonomic identity) grown in a controlled test of three spacings (0.5, 1.0, and 2.0 m) on an irrigated and fertilized site in western Washington. In each clone, samples included a very wide range of cambial growth rates, with ring widths from 1 to 19 mm. Growth rate, expressed in several ways, had no consistent effect on fiber length within rings of the same age for rings 2 6. For ring 7, however, there were positive correlations between most growth rate measures and fiber length. Whole-disk fiber length increased with overall growth rate as measured by stem diameter; this apparent anomaly is caused by the fact that fast-growing trees have more of their basal area concentrated in rings further from the pith than do slower growing trees, and these rings have longer fibers compared with rings closer to the pith. Close

• 5. [Article] Effects of release from suppression on wood functional characteristics in young Douglas-fir and western hemlock

  Little is known of wood properties in trees that were initially suppressed and subsequently released from suppression. The purpose of this study was to assess differences in growth ring width, specific ...

  Citation × Citation Citation Abstract Copy Title: Effects of release from suppression on wood functional characteristics in young Douglas-fir and western hemlock Author: Meinzer, F. C., Gartner, B. L., Renninger, H. J. Little is known of wood properties in trees that were initially suppressed and subsequently released from suppression. The purpose of this study was to assess differences in growth ring width, specific conductivity (Ks), tracheid dimensions, moisture content, and wood density in suppressed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) trees and trees released from suppression averaging 12-18 years of age. Growth ring width was 370% higher for Douglas-fir and 300% higher for western hemlock trees released from suppression, and Ks was 182% higher for Douglas-fir and 42% higher for western hemlock trees released from suppression. Earlywood width approximately four times greater after release in both species, whereas the relative increase in latewood width was much greater in Douglas-fir. Tracheids were 25% wider and 11% longer in released Douglas-fir trees. In western hemlock, released trees had 19% wider tracheids that were approximately the same length as those in suppressed trees. Moisture content was 66% greater in released Douglas-fir and 41% greater in released western hemlock. Wood density decreased by 21% in Douglas-fir trees and and by 11% in western hemlock trees released from suppression. However, wood density of released trees did not differ from average reported values, implying that wood from released trees may be suitable for many of its traditional applications. Title: Effects of release from suppression on wood functional characteristics in young Douglas-fir and western hemlock Author: Meinzer, F. C., Gartner, B. L., Renninger, H. J. Little is known of wood properties in trees that were initially suppressed and subsequently released from suppression. The purpose of this study was to assess differences in growth ring width, specific conductivity (Ks), tracheid dimensions, moisture content, and wood density in suppressed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) trees and trees released from suppression averaging 12-18 years of age. Growth ring width was 370% higher for Douglas-fir and 300% higher for western hemlock trees released from suppression, and Ks was 182% higher for Douglas-fir and 42% higher for western hemlock trees released from suppression. Earlywood width approximately four times greater after release in both species, whereas the relative increase in latewood width was much greater in Douglas-fir. Tracheids were 25% wider and 11% longer in released Douglas-fir trees. In western hemlock, released trees had 19% wider tracheids that were approximately the same length as those in suppressed trees. Moisture content was 66% greater in released Douglas-fir and 41% greater in released western hemlock. Wood density decreased by 21% in Douglas-fir trees and and by 11% in western hemlock trees released from suppression. However, wood density of released trees did not differ from average reported values, implying that wood from released trees may be suitable for many of its traditional applications. Close