Butt Logs Research Articles

Insect Damage to Wind-Thrown and Standing Live Black Cherry Resulting From Delayed Salvage After a Major Abiotic Disturbance

Severe windstorms that swept through three counties in northwestern Pennsylvania on July 21 and 22, 2003, caused extensive blowdown in many northern hardwood stands containing an extensive component of black cherry, Prunus serotina Ehrh. Although many species were affected by the storm, black cherry is the most valuable timber species in the region. A number of factors prevented salvage until 3 years after the storm. The purposes of this study were to identify the wood-boring insects that attacked damaged cherry and to estimate the value lost due to delayed salvage. The long-horned beetle Saperda imitans Felt and Joutel (Coleoptera: Cerambycidae) and the ambrosia beetle Xyleborinus saxeseni (Ratz.) (Coleoptera: Curculionidae: Scolytinae) were the most abundant wood borers reared from wind-thrown cherry. We also monitored both changes in the population of the bark beetle Phoeotribus liminaris (Ratz.) and the damage it caused to live residual cherry. Based on the average depth of S. imitans galleries and associated stain, the estimated grade loss of a 25-cm (10 in.) cherry log (large end) after slab removal was approximately 27% and for a 102-cm (40 in.) log it was 3.6%. Wood borer galleries occurred throughout the first 5.2 m (17 ft) of the butt log as well as in the upper bole and larger branches. The density of ambrosia beetle galleries on wind-thrown trees was highest on trees with dying and dead epicormics than on trees with live epicormics and higher on trees suspended off the ground. Catches of X. saxeseni in ethanol-baited, Lindgren funnel traps increased significantly from 2005 to 2006 as did numbers of P. liminaris and the gum spot damage these insects did to residual live cherry in 2005 compared with that in 2004. Results of this study indicate that the extent of insect damage after this abiotic disturbance was influenced by the time of year the damage occurred relative to the temporal activity of the insects involved and emphasizes the importance of swift salvage.

Qualidade da madeira serrada de Pinus elliottii Engelm. procedente de florestas resinadas

Neste estudo, objetivou-se caracterizar a qualidade da madeira serrada de Pinus elliottii procedente de florestas resinadas e processadas em uma serraria instalada no município de São José do Norte (RS). Para tanto, selecionaram-se, do processamento de desdobro, quatro toras basais e quatro toras superiores para cada uma das três classes diamétricas existentes. As peças originadas foram analisadas pós-desdobro e pós-secagem em estufa convencional convectiva. Constatou-se, em razão da inexistência de tratos silviculturais na floresta, a incidência de nós, principalmente nas peças de toras superiores, influenciando a classificação qualitativa dessas peças de madeira. Em relação à operação de resinagem, esta contribuiu para a maior incidência de bolsas de resina nas peças de toras basais, além de que, influenciou na classificação qualitativa da madeira. O surgimento de defeitos após a operação de secagem não alterou a classificação da madeira tanto oriunda de toras basais como de toras superiores.

Stem Sinuosity Changes in Young and Merchantable Stands of Pinus taeda

Abstract A survey of stem sinuosity severity and occurrence was conducted on six sites in North Carolina and South Carolina (USA) in Pinus taeda stands approximately 2 years after establishment. Approximately 1,400 trees on each site were measured for height, diameter, and degree of sinuosity in the stem at the beginning of the growing season and again after the completion of the growing season. Fifty-two percent of the trees increased in sinuosity over the growing season. Using stand records and observations by local foresters, two mature stands of loblolly pine (Pinus taeda) were located in the Atlantic Coastal Plain, where excessive stem sinuosity was reported to be present at ages 1 to 3 years. Seven trees were felled from each site. The 2.4-m butt logs were removed from each tree along with a 0.61-m bolt from the remaining felled tree. Slices were then cut through the log progressing through the pith. A single veneer containing the pith from each log was then selected for calculation of log volume, juvenile wood volume, and the volume of sinuous growth. Seven trees at the two sites were found to have had severe sinuosity earlier in their lives. Of the seven sinuous trees, three trees took only 1 year to correct the sinuous growth and return to a normal growth pattern. Two trees took an additional year to return to cylindrical growth, one tree returned to normal growth after the third year, and a single tree returned to a straight appearance by the end of the fifth year after the initiation of sinuous growth. Therefore, the sinuous portions of all seven trees were entirely contained within the juvenile core of the tree. Clear static bending specimens were machined and tested. Trees that were found to be nonsinuous produced mature wood that was significantly stiffer than the sinuous trees.

Effects of season and region on sapstain and wood degrade following simulated storm damage in Pinus radiata plantations

Storms causing windthrow are major natural disturbance events and an unpredictable hazard to forest planning. Knowledge of regional and seasonal climatic effects on sapstain and decay fungi will allow forest managers to minimise losses from wood deterioration during salvage operations. A study was conducted monitoring sapstain in trees that were experimentally felled to simulate storm breakage at up to four times during the year in Pinus radiata plantations across six locations in different climatic zones throughout New Zealand. It was found that drying of sapwood and development of sapstain depended more on the season when the storm occurred, rather than the time since felling. Sapstain appeared almost immediately in stems felled during summer, at some locations reaching more than 20% mean cross-sectional cover inside logs within 3months, whereas in those felled during winter an initial lag phase during the cooler months preceded a more rapid rise during spring and summer. Rates varied substantially between locations with a tendency for faster deterioration where average temperatures were greater. For trees damaged during winter, it was predicted that a P. radiata butt log with a mid-length diameter of c. 16–23cm will take from 2 to 8months, depending on climate, to reach an economic damage benchmark threshold of 10% cross-sectional sapstain cover. However, for storms in spring or summer this period reduces to less than 1month at warmer locations. Development of sapstain was uniform or increased slightly with height along the felled stem, but was greatest close to the felling cut in the basal section that would normally be removed during log retrieval. The results of this study provide new information about the temporal and regional variation in the dynamics of sapstain fungi that will assist forest managers during timber recovery following storms in regions with similar climates and tree species.

Evaluating Effects of Thinning on Wood Quality in Southeast Alaska

We examined the effect of thinning on wood quality of western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis) located on Prince of Wales and Mitkof Islands in southeast Alaska. Sample trees came from paired plots (thinned versus unthinned) in eight naturally regenerated, mixed stands of young-growth western hemlock and Sitka spruce in an effort to examine a range of thinning densities, from 10 X 10 ft to 20 X 20 ft spacing. The stands, which had been thinned in the late 1970s and early 1980s, ranged in age from 36 to 73 years at the time they were selected for this study in 2003. The main focus of the stand selection in this retrospective study was to find individual stands that included a thinned plot and an adjacent unthinned plot from the same original stand. A random sample of trees from both thinned and unthinned plots was selected, stratified by tree dbh. About 12 trees per species per stand (461 trees in total) were selected for the study. Selected trees were harvested, and a lumber recovery study was conducted, enabling us to relate log volume to recovered lumber volume by product grade. Surfaced dry dimension lumber was produced, graded, and nondestructively tested using the transverse E-vibration standard test for stiffness. We did not evaluate the resource for appearance-grade products. For each species, the overall treatment effect (thinned versus unthinned) on lumber grade recovery and transverse E-vibration modulus of elasticity by vertical-log position (butt log, middle log, or top log) were analyzed using a mixed-effects procedure. Results suggest that there were no significant differences in product recovery or value between the thinned plots and the untreated control plots in the manufacture of structural lumber products.

Sorting Eucalyptus nitens plantation logs using acoustic wave velocity

Summary Acoustic wave velocity (AWV) was evaluated as a predictor of wood stiffness in plantation-grown Eucalyptus nitens. To represent the resource currently being directed to the structural timber market, five harvest sites were selected in NE and NW Tasmania spanning two age classes (8 y and 13–15 y) and three productivity classes. A total of 155 sawlogs, 5.5 m long, were cut from 137 harvested trees. AWV was measured in both standing trees and in sawlogs in the mill yard. Disk samples were collected from the butt end of each log to determine green and basic density. Logs were then sawn, and structural boards dried and finished according to commercial processing practice. One sample board per log was then tested for stiffness, bending and shear strength and hardness. Sites differed significantly (P < 0.001) in standing tree AWV, log AWV and all wood properties of the butt logs, with the 13–15-y age class displaying higher AWV, wood basic density, stiffness and hardness than the 8-y age class. Log AWV2 explained 54% of the variance in board static modulus of elasticity (MoEstat) for the pooled data. At the age class level, 47% of the variance was explained for the 13–15-y logs, but the correlation was much poorer—explaining only 6% of variance in MoEstat—for the subset of 56 logs from the two 8-y-old sites. Dynamic MOE (MoEdyn, the product of green density and log AWV2), gave useful predictions of MoEstat for the younger age class. MoEdyn calculated using log AWV2 explained 56% of the variation in MoEstat, facilitating the segregation of logs into three stiffness classes. Tree AWV2 explained 40% of the variation in MoEstat for the pooled data, similarly enabling segregation of boards into three stiffness classes. Relative to segregation at the log level, a similar percentage of low-stiffness material was identified; but ability to identify higher-stiffness material was reduced. A significant (P < 0.01) positive correlation of 0.30 was found between board stiffness and hardness, indicating that segregation based on increasing stiffness would also improve hardness.

Influences of Conventional and Low-Density Thinning on the Lower Bole Taper and Volume Growth of Eastern White Pine

Abstract Throughout the northeastern United States, thinning is a common management practice in stands of eastern white pine (Pinus strobus L.), but foresters lack clear information as to whether conventional B-line or low-density thinning will best achieve their growth and financial objectives. Conventional management consists primarily of light crown thinning, whereas low-density management uses heavy crown thinning to isolate selected crop trees. To better inform silviculturists of the effects of these thinning regimes on volume growth and taper of white pine, we compared the lower bole taper—quantified as Girard form class (GFC)—and volume growth between the two thinning regimes and a nonthinned control. Over the 17-year study period, GFC increased among all treatments from an overall average of 0.77 — 0.01 (—SE) to 0.82 — 0.00. Trees under the B-line thinning regime had the most taper (lowest GFC), owing to a thinning-induced growth response at breast height but not at the top of the butt log. Low-density thinning, on the other hand, resulted in substantially larger, less tapered butt logs with significantly higher growth rates at both breast height and the top of the butt log. The volume growth of low-density trees was significantly higher than that of trees in the other treatments. At the stand level, however, the overall volume growth of the low-density treatment was significantly lower than that of the B-line treatment. Thus, this study reveals that when implementing low-density thinning, there is a tradeoff between overall stand growth and larger, less tapered individual trees.

Estimating Within Tree Spatial Changes in Acoustic Velocity in Felled Douglas-fir Stems

Sorting logs for stiffness in the woods using acoustic devices mounted on harvesters and processors could improve the allocation of logs to their most appropriate processing destinations. Estimating spatial changes in acoustic velocity in felled stems, based on a limited number of measurements, will be essential if they are not to unduly impact harvesting or processing productivity and costs. The effect of five variables (length from butt, bark percentage, moisture content, green density, and oven dry density) and four velocity measurement approaches (time of flight [TOF] across the tree bole, resonance of the full tree length, resonance of the first 3 m butt log segment, and resonance of a log segment between 6 and 9 m above the butt) on the ability to estimate spatial changes in acoustic velocity were evaluated in felled Douglas-fir stems from five stands in southwestern Oregon. Distance from the butt was a significant predictor of acoustic velocity along the stem. TOF acoustic velocity measured across the bole had little value in predicting the longitudinal resonance acoustic velocity of a section of the tree. Full tree length resonance acoustic velocity, or single log acoustic velocity (either 3 m butt log or 3 m log 6 m above the butt) were found to be statistically significant and strongly correlated predictors of acoustic velocity of a section of a tree (R2 ranging from 0.68 to 0.89). The models were found to be stand-dependent, indicating a possible need for calibration for each stand to be harvested.

Improved Methods for Achieving Traceability of Tree and Log Identities in Timber Processing Studies

We successfully tracked the identities of more than 550 selected 13-year-old trees from a Eucalyptus nitens (Deane &amp; Maiden) progeny trial through tree felling, harvesting of butt logs, and sawmill processing to finished sawn boards using a two-stage approach. To track log identity from the standing tree to the log yard, we used a numbered under-bark wooden identification plug, glued into a hole drilled in the trunk prior to harvesting. To track tree identity for individual sawn boards, log-end templates with corresponding tree identification numbers were glued to the log ends before milling. Materials and methods used withstood harvesting and debarking, log transportation, milling, air and kiln drying, steam reconditioning, and final machining. A second study confirmed the success of the under-bark plug method to successfully track 548 selected standing trees through harvesting and transportation to the mill.

Predicting sapstain and degrade in fallen trees following storm damage in a Pinus radiata forest

Storm damage in production forests constitutes a major source of economic loss world wide, yet the retrieval of salvageable timber remains problematic. In particular, an inability to anticipate when sapstain and degrade will appear hampers the planning of log recovery operations. A study was conducted to monitor the deterioration of fallen trees following two winter storms causing wind and snow damage in a Pinus radiata plantation forest in the upper South Island of New Zealand. Percentage sapstain, incidence of basidiomycete decay fungi, and frequency of bark beetle infestation increased, while percentage sapwood moisture content decreased, over a period of 1 year. These changes proceeded more rapidly in fallen trees that were severed at stump height, to simulate breakage, than in those that were left partially rooted. There was little beetle activity at the time of the storms, but Arhopalus ferus (Coleoptera: Cerambycidae), and Hylastes ater, Hylurgus ligniperda and Pachycotes peregrinus (Coleoptera: Curculionidae: Scolytinae), were collected in flight traps during the following spring and summer. The predominant fungal species associated with sapstain was Diplodia pinea, while Ophiostoma piceae and Grosmannia huntii were isolated near the end of the period. The main decay fungi obtained were Phlebiopsis gigantea, Stereum sanguinolentum, and Schizophyllum commune. A generalized linear mixed model was constructed to predict the development of sapstain in fallen trees for conditions prevailing during the study after a storm at the same time of year. According to the model, a 10m long butt log of 22cm mid length diameter will have minimal stain (<10% of the cross sectional area affected) when cut from severed stems up to 4 months after the storm; if taken from still-rooted trees this period will extend to 1 year. However, because of large between-tree variation, economically productive log recovery will also depend on the proportion of trees that lie below an acceptable sapstain threshold. Further research is needed to determine regional and seasonal influences on the development of sapstain in fallen trees.

A Hedonic Approach to Value Pinus radiata Log Traits for Appearance-Grade Lumber Production

Abstract This study used a hedonic approach to estimate the economic value of radiata pine log attributes (small-end diameter, form, and internode length) for appearance-grade lumber, including molding and better, shop, and industrial finger joint. Models were also built at the tree level to investigate the effect of selection as conducted by breeders. A Chilean sawing study provided information on wood traits and log out-turn for 156 logs divided into three classes: pruned butt log, second log, and third log. The conversion return of logs, instead of log prices, was used as the measure of log economic value. The economic values of log small-end diameter were 0.33, 0.19, and 0.10 US$/mm for the first, second, and third log, respectively. Concerning form, those values were US$2.6, US$1.4, and US$0.63 for a marginal improvement of this characteristic. The value of mean internode length was 0.19 US$/cm for second unpruned logs. Values for other internode length indices are also presented in this article. Branch variables were not statistically significant to explain the log recovery value. Finally, log recovery value was found to be elastic to the changes in small-end diameter and form, but inelastic to changes in the mean internode length.

Effects of Bear Damage on Douglas-Fir Lumber Recovery

Abstract Bear activity resulting in injury to Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees has been documented as early as the mid-1850s in the Pacific Northwest. The study reported in this article was designed to help managers decide whether the common practice of removing the damaged but potentially valuable butt section of the bottom log and leaving it in the woods is warranted. Thirty-four damaged and 28 undamaged trees were selected from three sites in western Washington where bear damage has been a persistent problem. Trees were felled and bucked into 16-ft lengths. The damaged trees in the sample had been injured at ages between 10 and 15 years at two sites and between 10 and 65 years at the third site. The primary scaling deductions were for ring and scar defects. The 16-ft butt logs from the damaged and undamaged trees were sawn into dimension lumber. Bear-damaged logs were found to have lower cubic volume recovery than undamaged logs having the same small-end diameters. Lumber grade recovery was also influenced by bear damage; logs from damaged trees had a lower percentage of high-value lumber. The analysis suggests that the optimal harvesting policy is to haul the entire butt log to the mill rather than leaving the damaged portion in the woods. Although the value of the damaged portion is lower, most of the lumber recovered from that section can be used, with only a modest reduction in grade and value.

Relationships between acoustic variables and different measures of stiffness in standing Pinus taeda trees

Acoustic tools are increasingly used to estimate standing-tree (dynamic) stiffness; however, such techniques overestimate static stiffness, the standard measurement for determining modulus of elasticity (MOE) of wood. This study aimed to identify correction methods for standing-tree estimates making dynamic and static stiffness comparable. Sixty Pinus taeda L. trees, ranging from 14 to 19 years old, obtained from genetic tests established in the southeastern United States, were analyzed. Standing-tree acoustic velocities were measured using the TreeSonic tool. Acoustic velocities were also recorded in butt logs cut from the same trees using the Director HM200. A strong but biased relationship between tree and log velocities was observed, with tree velocities 32% higher (on average) than the corresponding log velocities. Two correction methods, one for calibrating tree velocities and one for accounting for differences in wood moisture content, were used to determine an adjusted MOE. After correction, adjusted MOE estimates were in good agreement with static longitudinal MOE values measured on clearwood specimens obtained from the trees, and no systematic bias was observed. The results of this study show that acoustic estimates of MOE on standing trees largely depend on how the data are processed and the reference method used.

Comparing Timber and Lumber from Plantation and Natural Stands of Ponderosa Pine

Abstract Data derived from empirical studies, coupled with modeling and simulation techniques, were used to compare tree and product quality from two stands of small-diameter ponderosa pine trees growing in northern California: one plantation, the other natural. The plantation had no management following establishment, and the natural stand had no active management. Fifty trees of similar diameter classes were selected from each site, measured, bucked into logs, and sawn into boards, and the boards were scanned for defects. Trees from the plantation stand demonstrated less variability in tree height, crown length, and age structure. The plantation trees were on average 4 years younger than their natural cohorts, yet for all but the smallest diameter there were no significant differences between mean tree height or crown length. Predicted merchantable volumes differed significantly for the largest diameter class. Merchantable volume was estimated to be 5% greater for the plantation trees than for the natural stand trees. More logs were bucked from the plantation stands, resulting in greater lumber production and greater value overall. Butt logs from the plantation stand had an average of 9 whorls per log, whereas natural butt logs averaged 10 whorls per log. The most numerous defects, outnumbering knots and wane, were needle traces. These occupied some 31% of natural board surface area, in comparison with 19% for plantation boards. Given the shorter time frame required to grow plantation trees, the greater merchantable volumes, and more consumer-acceptable defects, plantation stands, even with a minimal level of management, offer greater product potential than natural stands.

Effect of drying technology on aspen wood properties

This article reports the impacts of three different drying treatments on selected physical and mechanical properties of European (Populus tremula L.) and hybrid (P. tremula x tremuloides) aspen wood. The material originates from 5 European aspen stands and 7 hybrid aspen stands in southern and central Finland. After processing the logs at a saw mill, sawn timber samples were dried using 1) conventional warm air drying, 2) press drying, or 3) heat treatment into Thermo-S grade by the Finnish Thermowood® method. Finally, small clearwood specimens were manufactured from different within-stem positions for the measurements of physical and mechanical properties. Both press dried and heat treated specimens absorbed water at significantly slower pace than the conventionally dried specimens. In normal climate, the conventionally dried, press dried and heat treated specimens conditioned at equilibrium moisture contents of 12.2, 8.7, and 8.9 per cent, respectively. It appears that the butt logs between 2–6 metres contain the lightest and, thus, weakest wood in aspen stems. Radial compression strength was at its highest in heat treated specimens, whereas conventionally and press dried specimens did not differ from each other. Press dried specimens had the highest longitudinal compression strength, also heat treated specimens showed higher values than the conventionally dried ones. Radial Brinell hardness of press dried specimens was higher than that of conventionally dried or heat treated specimens. Both modulus of elasticity and modulus of rupture were at their highest in press dried specimens. Irrespective of the drying treatment, the tangential shear strength of European aspen specimens was approximately 5% higher than that of hybrid aspen. Heat treated specimens indicated significantly lower tangential shear strength values than the conventionally dried ones. In case of both aspen species, the longitudinal tensile strengths of heat treated specimens were significantly lower than those of conventionally and press dried specimens. Heat treated specimens had the highest variability among the results. The inherent flaws in aspen wood material, e.g., wetwood and density

Modeling the effect of length on yield of sawn timber grades in Norway spruce (Picea abies (L.) Karst.)

The aim of the study was to model and analyse the effect of length on grade yield of timber from different stem parts in Picea abies, and to use the models to simulate the cost of reduced grade yield due to increased length. The boards were simulated having lengths ranging from 20 to 60 dm starting at stump level, 4 m above stump level and 8 m above stump level, respectively. Logistic regression models showed that length had a significant effect on grade yield, and this length effect was stronger in strength grading according to INSTA 142 (IN) compared to appearance grading according to Nordic Timber (NT). The length effect was most pronounced in butt logs, and somewhat greater in middle logs compared to top logs. Also a smaller length effect in inner boards compared to boards farther from the pith was found for IN-grading. The cost of the decrease in grade yield with increasing length will depend on the assumptions about the price gap between the grades. Current market prices in both grading rules gave a decrease in value of the sawn timber in stock by about 6% with an increase in the log length from 45 to 60 dm. In addition, a decrease in yield of timber in longer logs will amplify this effect, while a higher efficiency in the production process will diminish it.

Stem form variations in the natural stands of major commercial softwoods in eastern Canada

Stem form is often used as a sawlog assortment criterion and has an important effect on lumber recovery and mechanical properties. Based on 7018 stems collected from the natural stands in 3 regions in eastern Canada, this study quantified the variations in stem form (taper, sweep and eccentricity) for five major commercial softwood species, viz., jack pine ( Pinus banksiana Lamb.), black spruce ( Picea mariana), white spruce ( Picea glauca), red spruce ( Picea rubens) and balsam fir ( Abies balsamea). The majority of the stems had a diameter at breast height (DBH) ranging from 10 to 32 cm and total tree height from 10 to 20 m. Stem taper and butt taper increased steadily from 0.38 to 1.75 cm/m and from 0.74 to 4.23 cm/m, respectively, with DBH increasing from 8 to 48 cm. Stem sweep and basal sweep ranged from 0.12 to 7.28 cm/m and from 0.12 to 9.85 cm/m, respectively, with mean values of 0.87 and 0.95 cm/m. There were no significant differences in stem sweep and basal sweep between DBH classes and both sweeps distributed over a wide range within DBH classes, species and regions. About 0.77% of the stems and 1.2% of the butt logs had seriously curved shapes (sweep >3.0 cm/m). Eccentricity (ratio of smaller diameter to larger diameter) at the breast height (0.96) was very close to 1. Balsam fir and jack pine had the best and worst stem forms, respectively, while stem forms in black spruce were in-between. Butt logs were most seriously curved in red spruce and most tapered in white spruce. Region C (mainly eastern Quebec and the Atlantic Provinces) produced stems with smaller butt taper, basal sweep and stem sweep and larger eccentricity compared with other regions in eastern Canada. Overall stems in eastern Canada have a good stem form in terms of taper, sweep and eccentricity. The evaluation of stem form provides valuable timber quality information for the wood industry to optimize wood processing as well as for forest managers to define appropriate silvicultural regimes to improve stem form and economic value.

An estimate of timber degrade in Sitka spruce due to bark stripping by deer in a Scottish plantation

Summary Trees monitored for bark stripping over the previous 20 years were examined for timber defects by felling, then observing stain and rot in the split butt logs and strength testing wood samples. Logs (52 bark stripped, 28 controls) came from eight sites that had tree crops 28 – 39 years old; the logs were stratifi ed for wound size ( 180 cm 2 ), large wounds being rare. Many wounded logs had no stain or rot, but six of the 33 better-quality sawlogs were judged to be usable only for pulp. Modulus of elasticity and modulus of rupture were affected only at wounds and only in the sapwood there; at this position, mean stiffness and strength were both signifi cantly reduced compared with control logs, with lowest means for logs with large wounds. Large wounds suffered a much greater incidence of stain and rot than small wounds, but their rarity meant that the calculated fi nancial loss caused by the bark stripping estimated to be incurred over the whole rotation up to felling was only 3 per cent of the crop value.

Accuracy of Tree Grade Projections for Five Appalachian Hardwood Species

Abstract 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.

Influence of saw and secateur pruning on stem discolouration, wound cicatrisation and diameter growth of Betula pendula

The aim of this case study was to compare the impacts of saw and secateur pruning on silver birch (Betula pendula Roth). Data were collected from two saw pruned stands in 2005, and one secateur pruned stand in 2003. All the stands were located in southern Finland. The sample stems were felled, and their butt logs were sawn into flitches, whose knot features and colour defects were measured. In addition, discs were sawn from each stem in order to study the annual ring widths. In this material, pruning with secateurs appeared to cause less colour defects than pruning with a saw. Irrespective of the pruning method used, the colour defects in the stem wood were at their largest in cases where the basal knob or the stem bark appeared to be damaged by pruning. Colour defects spread mainly towards the pith, only in a few cases towards the stem surface. The cicatrisation time of the knots as well as the length of the bark stick remaining inside the stem did not show significant differences between the two pruning methods. Pruning of the lowest living branches appears to have no effect on the diameter growth of silver birch trees.