ARBORICULTURE ARBORICULTU URBAN FORESTRY Volume 31, Issue 6, November 2005 & CONTENTS Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) www.isa-arbor.com Shuju Bai, William R. Chaney, and Yadong Qi WOUND CLOSURE IN TREES AFFECTED BY PACLOBUTRAZOL .......................................................................273 Abstract. Experiments were conducted to investigate the effects of paclobutrazol on closure of wounds made through the bark or resulting from pruning branches in nine species of trees. The species studied were American sycamore (Platanus occidentalis L.), black walnut (Juglans nigra L.), European black alder (Alnus glutinosa L.), red oak (Quercus rubra L.), sweetgum (Liquidambar styraciflua L.), white ash (Fraxinus americana L.), white oak (Q. alba L.), white pine (Pinus strobsus L.), and yellow poplar (Liriodendron tulipifera L.). Paclobutrazol was applied using either the soil drench or soil injection method. Circular wounds (2 cm [0.8 in.] diameter) were made in the bark on the main stem, and branches were pruned from treated and untreated trees at the time of paclobutrazol application in the spring. The rate of wound closure was determined one, two, and three growing seasons aſter treatment. The rate of bark wound closure was reduced in paclobutrazol-treated black walnut, European black alder, red oak, sweetgum, and white oak. There was no difference in the rate of closure of wounds in the bark of treated and untreated American sycamore, white ash, white pine, or yellow poplar. The rate of pruning wound closure was reduced in black wal- nut, European black alder, red oak, sweetgum, and white oak, but was not influenced by paclobutrazol treatment in white ash, white pine, or yellow poplar. The inhib tory effect of paclobutrazol on closure of both bark and pruning wounds in some species persisted at least 3 years. Key Words. Bark Wound; Growth Retardant; Paclobutrazol; Pruning Wound; Tree Growth Regulator; Wound Closure. Jan Lukaszkiewicz, Marek Kosmala, Magdalena Chrapka, and Jacek Borowski DETERMINING THE AGE OF STREETSIDE TILIA CORDATA TREES WITH A DBH-BASED MODEL .........................................................................................280 Abstract. This paper evaluates the possibility of determining tree age based on diameter at breast height (dbh, taken at 1.3 m [4.3 ſt]), using co mon lime (linden, Tilia cordata). We first identified and measured groups of trees growing in similar conditions (alleys and road- side trees) whose age was known. We developed a regression model describing the growth of trees over time. Plotting tree age against diameter yielded a correl tion coefficient r2 = 0.962 and determination coefficient r2 = 0.926. The resulting model was applied to unre- lated groups of trees of known age. The difference between the actual age and mean age calculated with the model was less than 10%. The model was then compared to measurements taken with a Resistograph, with results being highly concordant. The model, although not meant for application to individual trees, might be useful in determinng the age ofcommon lime trees growing in alleys and along roads. Key Words. Common Lime; DBH; Linden; Roadside Trees; Tilia cordata; Tree Age. Michael R. Kuhns, Brook Lee, and Douglas K. Reiter CHARACTERISTICS OF URBAN FORESTRY PROGRAMS IN UTAH, U.S. ..........................................................285 Abstract. Urban/community forestry programs in Utah, U.S., were studied; a questionnaire was sent to community forestry contacts in every incorporated community in the state in summer 2002. Respondents reported on program support, budget, management authority and practices, strengths and weaknesses, and training and information needs. Program support from residents, town officials, and emplo ees was fairly strong, with 80% indicating some support. One-quarter of towns have a tree board and celebrate Arbor Day. Towns obtain assistance from nurseries or tree care businesses, Extension, and state forestry, in that order. Two-thirds of communities have a tree-related budget, with a mean budget of US$44,000 and a median budget of $3,000, averaging $2.58 per resident and $25.16 per tree. Total budget generally increased with population, but the smallest towns had the largest per capita and per tree budgets. Most towns spend enough to qualify for Tree City USA’s requirement of $2 per capita. The ratio of spending for maintenance versus planting increased from 0.6 for small towns to 4.1 for larger cities. Just under two-thirds of communities have forestry programs. The average number of public trees per town is about 2,300 (median 150), with numbers of trees increas- ing as population increased, but with trees per capita generally decreasing as population increased, ranging from 0.21 to 0.43 trees per person. Key Words. Urban Forestry; Community Forestry; Program; Utah; Arboriculture; Characteristics; Volunteer. ©2005 | International Society of Arboriculture | ISSN:1935-5297
November 2005
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