Arboriculture & Urban Forestry 34(2): March 2008 Arboriculture & Urban Forestry 2008. 34(2):133–134. 133 ARBORICULTURAL ABSTRACTS USE OF BRANCH CROSS-SECTIONAL AREA FOR PREDICTING PRUNING DOSE IN YOUNG FIELD-GROWN QUERCUS VIRGINIANA ‘CATHEDRAL’ IN FLORIDA, U.S. Jason Grabosky, Edward Gilman, and Chris Harchick Allometric relationships for trunk, first order branches and as- sociated foliage were developed to develop a repeatable pruning dose for wind interception studies on Quercus virginiana Mill ‘Cathedral’. Three trees were dissected to develop relationships. It was determined that leaf mass was linearly related to the basal area of the primary branch, consistent with pipe model expecta- tions. A pruning dose for leaf mass removal was defined by tracking basal branch areas and removing entire first order branches. Leaf mass was closely related to leaf surface area, however leaf mass varied with compass orientation while leaf area remained unchanged. The use of wood cross-section area conservation rules for branching in Lindenmayer (L-system) computer modeling is shown to be inconsistent with the data set, as is often observed in the field. The area conservation assump- tion is made to force taper into computer models, and departures are accepted by assuming heartwood formation forces imbalance into the model. The data set was developed from 3 year old or younger wood. The species is known to retain viable vessel elements in sapwood for at least 3 years in the areas surrounding the testing site. Since it is doubtful that there was heartwood or non-functional sapwood in the test trees, use of the area balance assumption for modeling by asserting heartwood influence is questionable. (Urban Forestry & Urban Greening 2007. 6:159– 167) QUANTIFYING AND RANKING THE FLAMMABILITY OF ORNAMENTAL SHRUBS IN THE SOUTHERN UNITED STATES Alan J. Long, Anna Behm, Wayne C. Zipperer, Annie Hermansen, Alexander Maranghides, and William Mell Wildfire preparedness programs focus on education and provide assistance with community design, home construction, and land- scape design. Wildland-Urban Interface (WUI) residents, nurs- ery employees, and landscape architects often request lists con- taining species that would be appropriate for placement in fire- wise landscaping. Existing lists were created from personal experience or based on lists originating in the western United States. These lists, when applied to southern landscape designs, have inconsistencies (2006 Fire Ecology and Management Con- gress Proceedings [DVD]. Quantifying and ranking the flamma- bility of ornamental shrubs in the Southern United States San Diego, CA: The Association for Fire Ecology/Washington State University Extension) THE EFFECT OF URBAN LEAF AREA ON SUMMERTIME URBAN SURFACE KINETIC TEMPERATURES: A TERRE HAUTE CASE STUDY Perry J. Hardin and Ryan R. Jensen The urban heat island effect (UHIE) has been documented in many temperate region cities. One cause of the UHIE is the replacement of green spaces with impervious materials as urban- ization commences and the city builds up and fills in. During the summer, elevated urban temperatures result in increased elec- tricity usage, higher pollution levels, and greater resident dis- comfort. Through evapotranspiration and the interception of so- lar radiation, increasing urban tree canopy cover can help miti- gate the UHIE. While this is universally accepted, the exact statistical relationship between urban leaf area (as measured by leaf area index, LAI) and urban temperatures has not been ex- tensively studied. In a case study conducted in urban/suburban Terre Haute, Indiana, USA, simple linear regression was em- ployed to quantify the relationship between in situ ceptometer LAI measurements and surface kinetic temperatures (SKTs) measured using thermal satellite imagery acquired at 1100 local time. For the 143 sample sites located in the study area, LAI accounted for 62% of the variation in surface temperature. For every unit increase in LAI, surface temperature decreased by 1.2°C. (Urban Forestry & Urban Greening 2007. 6:63–72) ASSESSING URBAN FOREST EFFECTS AND VALUES, WASHINGTON, D.C.’S URBAN FOREST David J. Nowak, Robert E. Hoehn III, Daniel E. Crane, Jack C. Stevens, and Jeffrey T. Walton An analysis of trees in Washington, D.C. reveals that this city has about 1,928,000 trees with canopies that cover 28.6 percent of the area. The most common tree species are American beech, red maple, and boxelder. The urban forest currently store about 526,000 tons of carbon valued at $9.7 million. In addition, these trees remove about 16,200 tons of carbon per year ($299,000 per year) and about 540 tons of air pollution per year ($2.5 million per year). The structural, or compensatory, value is estimated at $3.6 billion. Information on the structure and functions of the urban forest can be used to improve and augment support for urban forest management programs and to integrate urban forests within plans to improve environmental quality in the Washing- ton, D.C. area. (Resour. Bull. NRS-1. Newtown Square, PA: USDA, Forest Service, Northern Research Station. 2006, 24 pp.) ©2008 International Society of Arboriculture
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