Table of Contents C.M. Ryder and G.M. Moore The Arboricultural and Economic Benefits of Formative Pruning Street Trees .............................. 17 Abstract. Research was undertaken to determine the need for, and costs of, formative pruning recently planted street trees. Specimens of Corymbia citriodora (48), Platanus × acerifolia (104), Pyrus calleryana (79), Quercus Ulmus parvifolia (52) were surveyed. Health was similar for all species, but form and structure varied. Data showed that codominant stems (68%) and included bark (40%) in the canopy or trunk were by far the most common structural palustris (65), and defects. Codominant stems were reported in 92% of all Ulmus parvifolia, 66% of Quercus palustris, 61% of Pyrus calleryana, 44% of Platanus × acerifolia, and 19% of Corymbia citriodora. The number of trees of a species that displayed no struc- tural defects was 25% or less except for Corymbia citriodora with 60% showing no structural defects. The pruning required to rectify these structural defects was recorded and then multiplied by a time factor for pruning with secateurs (hand prun- ers), a handsaw, or a pole pruner. Total time was then converted to an economic cost using current labor market prices. Platanus × acerifolia required the most work per tree with a final formative pruning cost of AUD $4.13 followed by Ulmus par- vifolia ($3.25), Pyrus calleryana ($2.76), Quercus palustris ($1.62), and Corymbia citriodora ($0.99). This compares with an average cost of $44.59 per tree for structural pruning 20 year old trees. Formative pruning makes sound arboricultural and economic sense. Key Words. Arboricultural Labor; Cost Benefit Analysis; Natural Target Pruning; Tree Management. Craig A. Tinus and Michael LaMana Conversion Efficiency and Economics of Urban Wood Utilization ................................................. 25 Abstract. Because of changes in land-use zoning, many standard forest management activities are no longer possible in urban and suburban woodland properties being developed. This trend has created an influx of wood fiber into municipal land- fills at significant cost to both landowners and municipalities. An alternative to landfill or other off-site disposal was evalu- ated that returned wood products to the landowner in a fee-for-service business model. Additionally, the cost for removal was modeled in comparison to the potential value of the wood as lumber.In a case study, the overall average marginal difference to the landowner for material removal was a cost of USD $35 from all job sites (n = 21); which was essentially break-even. This approach was cost competitive with landfill disposal, and landowners were able to benefit from wood products derived from trees that were being removed because of site development. Additionally, these landowners were preferentially choosing a form of material recycling that likely reduced the load to municipal waste disposal sites, and as such was a benefit to the community. Key Words. Avoided Disposal; Hedonic Valuation; Log; Lumber; Municipal; Recycling; Sawmill; Wood Waste. Daniel C. Burcham, Eng-Choon Leong, Yok-King Fong, and Puay-Yok Tan Infrared Camera Measurements Reveal Diurnal Variation in the Effect of Mechanically Induced Internal Voids on Stem Temperatures of Small Trees Passively Heated by the Sun ........................ 31 Abstract. The relationship between stem temperature measured by an infrared (IR) camera and a tree’s internal condition was pro- posed as a basis for diagnosing potentially hazardous defects in the landscape. Before practical application, this diagnostic technique needs clarification to guide expectations of its resolution and precision. In this study, cylindrical voids of varying size were created in 5 cm diameter stems of Dracaena fragrans and Syzygium grande by mechanically removing tissue from specimens in an outdoor nurs- ery, and the surface temperature of these plants was measured twice daily at 0830h and 1830h using an IR camera. The collected IR images were analyzed using a concurrent mixed methods approach with qualitative image evaluation and quantitative temperature analysis where the temperature distributions of stems containing internal voids were compared to those without defects. For both spe- cies, there was no difference in stem temperatures, as observed in IR images, among any experimental plants at 0830h, but an anoma- lous temperature reduction was exclusively apparent at 1830h near the 3.8 cm void, occupying 76% stem cross-sectional area. There was also a larger decrease in the linear temperature trend (0.34°C–0.51°C) near this void margin compared with other treatments, although this was more pronounced in the monocot species than eudicot. The remaining treatments did not exhibit stem tempera- tures visibly different from the control. Under experimental conditions, the technique identified relatively large internal defects, but the reduced heat capacity of stems containing such defects is only apparent in the evening after being passively heated by the sun. Key Words. Diagnostic Device; Dracaena fragrans; Infrared Camera; Internal Defect; Singapore; Syzygium grande, Temperature; Thermal. ©2013 | International Society of Arboriculture | ISSN:1935-5297
January 2013
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