Stem Quality of European Beech in Latvia and Its Effect on Tree and Stand Monetary Value

Beech is expected to expand its range into the territory of Latvia due to climate change, but we lack information on its stem and wood quality as a measure of its economic importance. We studied external stem quality traits in beech stands with age of 69 to 131 years. Nine trees were cut and sampled to determine internal wood quality and the proportion of peelable cylinder. Tree value was calculated according to buckling by dimensions and buckling accounting for stem and wood defects. Trees of the second generation (69 years) had a significantly lower incidence of frost cracks (22.0% vs. 36.2%), epicormic branches (50.5 % vs. 65.8%), and forks (15.8% vs. 23.5%) as compared to trees from the first generation (115–131 years). All sampled trees had discolouration in the height of the first log. The proportion of the peelable cylinder was positively linked to tree height and ranged from 12% at the stump level to 33.4% at the tree height of 30 m. All analysed phenotypic traits decreased stand monetary value: frost cracks by 6% to 8%, all external traits by 16% to 20%, all external and internal traits by 29% to 33%.

Optimizing Reduction Pruning of Trees Under Electrical Lines: The Influence of Intensity and Season of Pruning on Epicormic Branch Growth and Wound Compartmentalization

Reduction pruning of the main stem is commonly used during the maintenance of power lines to encourage the establishment and development of scaffold limbs away from wires. Understanding the physiology of epicormic branch initiation and growth as well as wound compartmentalization following reduction pruning are important for optimizing the pruning cycle and maintaining healthy and safe trees. In this study, the influence of both intensity and time of year of pruning on epicormic branch response and wound compartmentalization was investigated on 56 11-year-old Pennsylvania ash trees (Fraxinus pennsylvanica Marsh.) about 5 to 7 m in height within a controlled nursery environment. During the second growing season following reduction of the main stem, the number, height, and volume of epicormic branches, as well as tallest epicormic branches and the area of discolored wood, increased with pruning intensity. Pruning during the leaf-on season compared to the leaf-off season limited the establishment and development of epicormic branches without affecting wound-closure rate or the area of wood discoloration at the cutting point. Results are consistent with the known seasonal fluctuation of carbohydrates reserves. In the context of the electrical distribution network, where trees are subjected to pruning throughout the year, trees pruned in summer during a maintenance cycle could be pruned during the next cycle, in winter, and so on, to optimize the return interval of the pruning cycle.

Distribution of epicormic branches and foliage on Douglas-fir as influenced by adjacent canopy gaps

The influence of adjacent canopy gaps on spatial distribution of epicormic branches and delayed foliage (originating from dormant buds) was investigated in 65-year-old coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco). Sample trees were selected across a broad range of local densities (adjacent canopy gap sizes) from a repeatedly thinned stand in which gaps had been created 12 years prior to our study. Lengths and stem locations of original and epicormic branches were measured within the south-facing crown quadrant, along with extents to which branches were occupied by sequential (produced in association with terminal bud elongation) and (or) delayed foliage. Epicormic branches, while prevalent throughout crowns, contributed only 10% of total branch length and 2% of total foliage mass. In contrast, delayed foliage occupied over 75% of total branch length, accounted for nearly 39% of total foliage mass, and often overlapped with sequential foliage. Canopy gap size did not influence original or epicormic branch length or location. On original branches, larger gaps may have modestly negatively influenced the relative extent of sequential foliage on branches and (or) slightly positively influenced delayed foliage mass. Delayed foliage appears to contribute substantially to Douglas-fir crown maintenance at this tree age, but canopy gap size had a minor influence, at least in the short term.

Ergebnisse eines Grünästungsversuchs mit Bergahorn, Buche, Eiche und Esche

Results of a green pruning experiment with maple, beech, oak, and ash Object of the investigation is a pruning experiment in maple, beech, oak and ash stands in southwest Germany, which started in 2004. Aim of the experiment was to quantify the effects of green pruning on wood decay, discoloration, epicormic shoot formation, radial increment, and occlusion time. At top heights of 8–14 m, trials for each species were placed in stands where the natural pruning had not yet reached the achieved knot-free bole length. In each trial, ten trees were pruned in spring and summer respectively, by cutting 40% of the crown in average and branches up to 80 mm diameter. Additionally, ten unpruned trees were selected on each trial and, as the pruned trees, released from competitors. In 2011 and 2012 respectively, the trees were felled and measured, and wood samples with branches were taken and analysed. Results show that green pruning did not cause any wood decay. Compared to the control trees, increased discoloration was observed in the stems of the pruned trees. However, this was limited to the knotty center of the trunk and did not diffuse to the knotless part. Pruning intensified the formation of epicormic branches, but, except for oak, these branches diminished to the level of the control trees already during the time of observation. Radial increment shows a short-term decrease due to the green pruning, but with an extent below the effect of the dry year in 2003. With branch diameters of 3–4 cm, the pruned trees needed three to five years until the branching wounds were occluded, whereas about nine years were necessary for trees with natural pruning.

Accuracy of Tree Grade Projections for Five Appalachian Hardwood Species

The potential value increase of individual trees is an important factor in planning effective forest management strategies. Similar to other investments, trees with high potential value increase are retained and allowed to grow, and those with relatively low potential value increaseare harvested so that the proceeds may earn a higher rate of return elsewhere. Tree grade is used to assess the quality and value of wood within a tree; thus, projecting tree grade is an integral part of estimating potential value increase. This study measured the accuracy of projected treegrades over a period of 12–15 years for 588 black cherry, 404 northern red oak, 167 red maple, 191 white and chestnut oaks, and 450 yellow-poplar sawtimber trees in both thinned and unthinned stands. Projected grade was based on surface defects and percent volume deductions for sweep,crook, and rot at the time of the projection with the assumption that the threshold dbh for the highest possible grade would be reached in the future. This approach allows the forest manager to make grade projections based on what is visible and measurable on the tree, even if the tree iscurrently too small to qualify for higher grades. In general, grade projections were somewhat accurate, with 9% of trees higher than the projected grade, 80% projected correctly, and 11% lower than the projected grade. Trees that had a lower-than-projected grade usuallyexhibited additional deductions for percent cull volume and/or new epicormic branches. Grade projections were less accurate for larger, higher-quality trees because requirements for the top grade are more constraining and sensitive to changes in butt log characteristics than lower grades.For black cherry and northern red oak, grade projections in thinned stands were less accurate compared with unthinned stands because of resulting logging wounds or new epicormic branches.

Effects of Crown Release on Growth and Quality of Even-Aged Red Maple Stands

The effects of six crown-release treatments on growth and bole quality of 54 dominant, codominant, and intermediate red maples (Acer rubrum L.) were examined in an even-aged stand in upper Michigan. Treatments included an unreleased control, a single-tree and a two-tree crown release, and a full crown-to-crown release of 5, 10, and 15 ft. Twenty-two years after treatment, all trees showed a decrease in number of defects. Trees released to 15 ft lost twice as many defects as unreleased trees. Codominants and intermediates lost twice as many defects as dominants. Overgrown knots were the most common defects and showed the greatest decrease over time. The number of epicormic branches also declined; dominants had no epicormic branches after 22 years. Growth was greater for all released trees than for unreleased trees. Twice as much growth occurred in the 15-ft treatment as in the control, but this result was not significantly greater than those of the 5- or 10-ft crown release treatments. Dominant trees grew significantly more than the intermediate trees. Twenty-two years after treatment, dominants appeared to be least affected by crown-release but had the fewest defects and largest diameters. Crown-release treatment had the greatest effect on intermediates. To maximize growth and maintain bole quality, a crown release of between 5 and 10 ft is recommended for red maple pole-size trees in the Lake States.

Effects of Thinning in a Cherrybark Oak Plantation

A cherrybark oak plantation was established on an Upper Coastal Plain creek bottom in southwest Arkansas in 1962. At age 10, treatments of (1) thinning only, (2) thinning and pruning, and (3) a control (no treatment) were applied in three replicates. Repeated thinnings from below occurred in the thinned and thinned/pruned plots at ages 21, 26, and 31. Pruning was applied in the thin/prune plots only once, at age 10. Thinning had significant effects on diameter growth immediately and continued to accelerate diameter growth through age 39, but had no effect on total tree height. Height to live crown was significantly lower for thinned plots than in the control. Pruning appeared to have no effect on diameter, height, or number or height of epicormic branches. Sawtimber volume and accumulated sawtimber production was significantly greater in treatments that received thinning, with potential for greater economic returns. The reader is cautioned that these results may not be indicative of cherrybark oak plantations in the South due to the size of the study area and possible edge effects. South. J. Appl. For. 28(1):55–58.

Crop Tree Release Increases Growth of Mature Red Oak Sawtimber

Crop tree thinning plots were established in five stands of mature red oak (Quercus rubra, Q. velutina, and Q. coccinea) sawtimber in 1995. Initial stand ages ranged from 74 to 94 yr old with mean crop tree diameters ranging from 10.9 to 15.4 in. Growth of crop trees was monitored for the next 6 yr. The upper age limit at which oaks respond to crop tree management (high thinning) is at least 90 yr old. Although there was no significant difference in diameter growth between released and unreleased trees for the first 2 yr after release, diameter growth of released trees was significantly greater during each of the subsequent 4 yr. Crop tree release increased diameter growth of sawtimber red oak by 53%. Annual volume growth (International 1/4) increases ranged from 95% for 11 in. trees to 25% for 20 in. trees. Growth of crop trees has not decreased, relative to control trees, 6 yr after release. Formation of new epicormic branches on the butt log was largely limited to the slowest growing trees. Crop tree management should be considered as a method of managing sawtimber oak stands where maintaining high forest cover and noncommodities attributes are important considerations.

Epicormic Branches Affect Lumber Grade and Value in Willow Oak

A case study was conducted in a 50-yr-old bottomland oak stand in central Alabama to investigate the relationship between epicormic branches and lumber grade and value in willow oak (Quercus phellos L.). The stand had been thinned from below 7–10 yr earlier, resulting in a wide variety of epicormic branch conditions on the residual trees. A sample of 41 willow oak trees was selected before the stand was clearcut in late 1991. All merchantable logs in each tree were graded prior to felling. Average dbh of sampled trees was 19.1 in. Each tree averaged 9.5 epicormic branches on the sawlog portion of the bole. From these 41 trees, a random sample of 57 logs (31 butt logs and 26 upper logs) was shipped to a sawmill where they were sawn into lumber and graded. Epicormic branching had a large detrimental effect on log grade of individual trees. In general, as few as five epicormic branches somewhat evenly distributed on a 16 ft log was enough to cause a reduction in log grade. More importantly, defects caused by epicormic branches had a serious effect on lumber grade, particularly in the higher grades. Over 50% of the lumber volume that would have been graded as either First and Seconds or Select in the absence of epicormic branches was downgraded to No. 1 Common or below due to defects caused by epicormic branches. Based on lumber prices prevailing at the time of the study, defects caused by epicormic branches resulted in a 13% reduction in the value of the lumber produced in the final harvest. South. J. Appl. For.25(3):136–141.