ARBORICULTURE ARBORICULTU & CONTENTS URBAN FORESTRY Volume 42, Issue 3, May 2016 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) ® www.isa-arbor.com Matt Follett, Charles A. Nock, Christian Buteau, and Christian Messier Testing a New Approach to Quantify Growth Responses to Pruning Among Three Temperate Tree Species ..............................................................................................................................133 Abstract. In settled areas, electrical line safety is maintained by pruning encroaching trees. Identifying key predictors of branch elongation growth rate following pruning would assist in developing predictive models and optimizing pruning cycles. However, measuring branches in trees near electrical lines is complex and challenging. This paper describes an innovative approach using a handheld laser rangefinder to safely and accurately estimate growth from the ground. In-tree and ground-based laser measurements were highly correlated. This was followed by testing for cor- relations between branch growth response over a number of years aſter pruning and many biotic and abiotic factors for Fraxinus pennsylvanica, Acer platanoides, and Acer saccharinum, in the city of Montréal, Canada. In a sample of 59 trees, A. saccharinum had the greatest branch growth, followed by F. pennsylvanica, and finally A. platanoides. Branch growth increased following pruning and subsequently strongly declined, with A. platanoides declining the fastest. Branch inclination angle was positively correlated with growth rate for two species, but not for A. saccharinum. Among the types of pruning used, directional pruning techniques resulted in the least branch regrowth rate. Tree diameter was weakly related to branch growth rates. These results suggest that while growth conditions for street trees may be perceived as homogenous, there is substantial variation in branch growth response. This variation may be related to pruning history, or unmeasured abiotic or biotic variables. Estimating pruning cycle duration is a complex task and further work is needed to develop a predictive model for more accurate estimation of return times. Key Words. Acer platanoides; Acer saccharinum; Branch Growth; Canada; Fraxinus pennsylvanica; Growth Modeling; Laser Rangefinder; Prun- ing; Québec; Urban Forestry; Utility Pruning; Vegetation Management. ® Joseph B. Townsend, Thomas W. Ilvento, and Susan S. Barton Exploring the Relationship Between Trees and Human Stress in the Urban Environment ...........146 Abstract. The research literature describes a positive relationship between seeing plants and human well-being. More rapid recovery from sur- gery, reduced incidence of neighborhood crime, increased baby birth weight, and increased trust of neighborhood merchants are among the benefits attributed to exposure to trees and shrubs. This study attempted to find a common explanation for these outcomes. It examined the connection between urban trees and neighborhood stress. Each of the stated outcomes can be attributed, in part, to stress reduction. The lit- erature indicated that stress reduction is one of the consequences of exposure to plants. Stress levels were measured at the block level in Wilm- ington, Delaware, U.S., by means of a survey mailed to 2,704 residents. Physical conditions were catalogued using an on-site inventory. The survey and inventory demonstrated that the total number of trees on a block has a strong negative relationship with neighborhood stress and a positive relationship with self-reported health. The results suggest that moderation of stress is one of the factors that underlies the beneficial consequences of exposure to green vegetation on inner-city blocks. This research should prove useful to city planners and urban residents alike. Key Words. Cross-reference Directory; Delaware; Hassles and Upliſts Scale; Human Stress; Perceived Stress Scale; Street Trees; Survey; Tree Canopy; Tailored Design Method; Tree Inventory; Wilmington. Edward F. Gilman, Maria Paz, and Chris Harchick Impact of Nursery Root Pruning and Tree Orientation at Planting on Growth and Anchorage .......160 Abstract. Root pruning by shaving 12 L container root balls when shiſting to 51 L containers did not impact Acer rubrum L. or Quercus virginiana Mill. root architecture within the top 12 cm of planted 51 L root balls five years later, despite marked differences at plant- ing, and had no impact on tree height or trunk diameter increase. Root pruning in the nursery did not affect bending stress required to tilt Acer trunks up to five degrees (anchorage) either one, two, or three years aſter landscape planting. In contrast, anchorage was greater the second year aſter planting Quercus that were root pruned. Rotating trees 180 degrees at planting from their orientation in the nursery had no impact on Acer or Quercus anchorage, tree height, or trunk diameter. Rotating oak (not maple) trees 180 degrees at planting increased root cross-sectional area growing from the hot (south) side of the root ball when trees were rotated at planting. Key Words. Acer rubrum; Anchorage; Bending Stress; Maple; Oak; Quercus virginiana; Root Ball Shaving; Root Morphology; Root Pruning; Winching. ©2016 | International Society of Arboriculture | ISSN:1935-5297
May 2016
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