Table of Contents Edward F. Gilman, Forrest Masters, and Jason C. Grabosky Pruning Affects Tree Movement in Hurricane Force Wind ......................................................................................... 20 Abstract. The goal of this study was to determine how different pruning techniques affect trunk movement on live oak subjected to hur- ricane force winds. Tree movement in wind on nonpruned trees was compared with movement on trees with crowns thinned, reduced, or raised. Twenty trees were blown using a wind generator up to 45 m/s (110 mph) maintained for 3 min. Each tree was instrumented with three orient tion sensors at set heights along the trunk to measure its deflection. Thinning or reducing crowns significantly reduced upper trunk movement at all wind speeds, whereas raising did not. Lower trunk movement was not affected by pruning type. These data indi- cated that foliage and branches toward the top of tree crowns were largely responsible for trunk movement in straight-line wind with those toward the bottom less important. Trees that are reduced or thinned in the manner described could receive less damage in windstorms. Key Words. Crown Raising; Crown Reduction; Crown Thinning; Hurricanes; Tree Damage. Glynn C. Percival and Ian P. Keary The Influence of Nitrogen Fertilization on Waterlogging Stresses in Fagus sylvatica L. and Quercus robur L. .................................................................................................................... 29 Abstract. The aims of this study were to determine the influence of nitrogen (N) fertilizers on tree tolerance under prolonged waterlogging co ditions and investigate the effect of N fertilization on aiding tree recovery from waterlogging damage using containerized English oak (waterlo ging-inter- mediate) and European beech (waterlogging-sensitive) as test species. English oak proved to be more waterlogging-tolerant than Eur pean beech. Tree vitality as measured by chlorophyll fluorescence, photosynthetic rates, leaf chlorophyll content, stomatal conductance, leaf and root protein concentration, and foliar N content was consistently higher in trees in which N fertilizers were added to the waterlogged solutions compared with trees waterlogged with tapwater only for 18 days. Measurement of light absorbance, light trapping, electron transport, and dissip tion fluxes per leaf cross-section of photosystem II aſter the 18-day waterlogging period indicated a beneficial influence of N fertilization on leaf photosynthetic pro- cesses at the cessation of the waterlogging period. Addition of N induced greater resource allocation in favor of roots over shoots in both tree species. At the cessation of the 18-day waterlogging period and aſter a 10-day regeneration period, growth (leaf area, shoot, root, total plant dry weight) was constantly higher in N waterlogged trees compared with non-N waterlogged ones. In a separate study, recovery rates of trees as measured by chlo- rophyll fluorescence, photosynthetic rates, leaf chlorophyll content, and stomatal conductance over a 6-week period aſter the cessation of 18 days waterlogging were 30% to 50% higher in N-fertilized trees compared with non-N-fertilized trees irrespective of species. In all cases, nonfertilized trees had the least capacity for recovery. In addition, leaf area, shoot, root, and total plant dry weight were higher in N-fertilized trees compared with nonfertilized ones. Results of this investigation indicate 1) applications of N fertilizers enhance the tolerance of trees under prolonged waterlogged conditions; and 2) applications of N fertilizers aſter waterlogging stress would be of benefit to improve tree recovery rates and growth. From a practical point of view, N fertilization 14.5 g (0.51 oz) or greater N per liter (0.26 gal) of water is tentatively suggested based on preliminary results of this study. Key Words. Chlorophylls; Chlorophyll Fluorescence; English Oak; European Beech; Photosynthesis; Physiogenic Stress; Plant Health Care; Protein; Root Deoxygenation; Stress Enzymes, Stress Tolerance. Bonnie L. Lewis and John G. Boulahanis Keeping Up the Urban Forest: Predictors of Tree Maintenance in Small Southern Towns in the United States .................................................... 41 Abstract. A mail survey of mayors of small towns in 13 southern states assessed the importance of urban forests and current urban forest pra tices. Topics covered were local tree management practices, resource allocation, and community influence. The findings, based on the responses of 504 mayors, indicate that small southern towns vary widely in their support of urban and community forests. Descriptive and multivariate analysis showing the relative effects of several predictors of basic tree maintenance indicate that basic solutions are near at hand. A clear linkage of state resources and organizational structure to local tree maintenance supports the important role played by the U.S. Department of Agricu ture Forest Service and its support for state agencies. In addition, the particular challenges communities face are outweighed by other factors. Key Words. Small Towns; Urban and Community Forestry; Urban Forest Management. Joseph Heimlich, T. Davis Sydnor, Matthew Bumgardner, and Patrick O’Brien Attitudes of Residents Toward Street Trees on Four Streets in Toledo, Ohio, U.S. Before Removal of Ash Trees (Fraxinus spp.) from Emerald Ash Borer (Agrilus planipennis) ............................... 47 Abstract. Toledo, Ohio, U.S. residents on four streets in an area with mature street trees, including ash, scheduled for removal as a result of attack by emerald ash borer were surveyed to determine their attitudes toward their street trees. Toledo is in the process of removing some 5,000 trees. Large trees with a variety of summer and fall foliar characteristics were highly valued suggesting that residents would be satisfied with a mix of species rather than planting each street to a single species. The fact that their trees canopied the street was also important to residents and is cha acteristic of larger urban trees. Residents would be pleased if replacements were planted before removing existing trees. Flowers were not a significant concern for resi- dents. In Toledo, as it is in many communities, the primary maintenance concern regarding trees in this survey is the potential damage to sidewalks. Key Words. Agrilus; Ash Replacements; Community Safety; Emerald Ash Borer; Fraxinus spp.; Green Ash; Resident Attitudes; Street Trees. ©2008 | International Society of Arboriculture | ISSN:1935-5297
January 2008
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
