ARBORICULTURE ARBORICULTU & CONTENTS higher in the frozen samples, but URBAN FORESTRY Volume 42, Issue 4, July 2016 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) ® www.isa-arbor.com Andrew K. Koeser, Drew C. McLean, Gitta Hasing, and R. Bruce Allison Frequency, Severity, and Detectability of Internal Trunk Decay of Street Tree Quercus spp. in Tampa, Florida, U.S. ...............................................................................................................217 Abstract. Wood decay is a factor considered in all commonly accepted tree risk assessment methods; however, few stud- ies have attempted to assess its presence in the urban forest or its predictability given visual cues and site factors. A random sam- pling of trees situated on hurricane evacuation routes was inventoried and assessed for risk in the city of Tampa, Florida, U.S. In addi- tion to a basic visual assessment, a sampling of larger diameter (>30.5 cm) live oak (Quercus virginiana) and all large diameter laurel oak ® (Quercus laurifolia) trees were tested with a resistance-recording drill to determine the amount of decay present (look- ing specifically at the sound-wood-to-stem-diameter ratio). Overall, 56.9% of the trees tested had some level of decay, though the incidence of decay was higher in laurel oak (67.4%) than in the live oak (29.4%). Additionally, tree species (P < 0.01), diam- eter (P < 0.01), and the presence or absence of visual decay indicators (P = 0.03) were all significant predictors of decay presence. Key Words. Advanced Assessment; Basic Assessment; Decay Incidence; Decay Severity; Florida; Laurel Oak; Live Oak; Quercus laurifolia; Quercus virginiana; Risk Assessment; Tampa; Visual Risk Assessment. Gregory Dahle, Aaron Carpenter, and David DeVallance Non-Destructive Measurement of the Modulus of Elasticity of Wood Using Acoustical Stress Waves .............................................................................................................................227 Abstract. Many biomechanical models include modulus of elasticity (E) but it is not always available in the literature. It would be useful to directly measure E for species, and one of the standard techniques for doing so is to utilize a universal testing machine (UTM). While laboratory testing can determine static flexural modulus of elasticity using a UTM, it requires destructive sampling and therefore is only useful aſter a tree or limb has been removed. Acoustic testing can be used to estimate the dynamic modulus of elasticity (DMOE) of wood, by measuring the speed of sound through a sample of wood without the need to remove any wood samples. This research investigated if acoustic testing can be used to accurately estimate the modulus of elasticity of green wood. Stump sprouts arising aſter a shelterwood harvest were cut and leſt at room temperature (21.1°C, warm) or conditioned to -6.7°C (frozen). The modulus of elasticity was measured using a stress-wave timer (DMOE) and a UTM (ES). The DMOE was temperature did not affect ES . While Temperature. Edward F. Gilman, Maria Paz, and Chris Harchick Effect of Liner Container Size, Root Ball Slicing, and Season of Root Pruning in a Field Nursery on Quercus virginiana Mill. Growth and Anchorage After Transplanting ....................................234 Abstract. Size of liner, root ball slicing when field planting, and field root pruning season were tested with intention of optimizing post- transplant performance of field-grown nursery stock. Trees planted into a field nursery from three container sizes and either root ball sliced or not when shiſted to larger containers or planting to the field nursery, and root pruned in the field nursery in either the dormant sea- son or growing season all had the same trunk diameter (144 mm) and tree height (6.4 m) three years aſter transplanting into the land- scape. Container size influenced root attributes—including number and orientation—and anchorage rating of field-harvested trees. Trees planted from 11 L containers required more bending stress to winch trunks evaluated 12 and 25 months aſter transplanting than larger containers. Percentage of root systems graded as culls was reduced from 88 to 66 by root pruning when field planting, but root prun- ing resulted in a slight reduction in anchorage rating. Diameter of the ten largest roots at edge of field-harvested root ball decreased with size of container planted into field soil. Root pruning season had no impact on final tree height (4.3 m) at the conclusion of field production. Key Words. Anchorage; Bending Stress; Container Volume; Dormant Season; Growing Season; Live Oak; Planting; Quercus virginiana; Root Architecture; Root Depth; Root Pruning; Transplanting. the stress-wave timer used in the study found a slightly higher E than a UTM, a simple prediction equation was determined for converting the results. Researchers believe tools such as this can be successfully utilized by the arboriculture industry to rapidly assess the modulus of elasticity of standing trees in the field. Key Words. Acoustic Testing; Biomechanics; Dynamic Modulus of Elasticity; Green Wood; Northern Red Oak; Quercus rubra L.; Stress Wave; ©2016 | International Society of Arboriculture | ISSN:1935-5297
July 2016
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