Percival G.C.,University of Reading |
Smiley E.T.,Bartlett Tree Research Laboratories
Urban Forestry and Urban Greening | Year: 2015
Accidental (strimmer, mower) or malicious girdling of ornamental trees is a frequent and underestimated problem in urban landscapes. No guidelines exist for landscape managers on the likelihood of fatal damage according to time of girdle, i.e., season (spring, winter) and extent of girdling. This report investigated the effect of stem girdling (0%, 25%, 50%, 75%, 100%) performed either during winter or spring on semi-mature birch (Betula pendula Roth.) and English oak (Quercus robor L) trees over a five-year period.1.All English oak survived any amount of girdling irrespective if girdled in spring or winter. Silver birch was more sensitive to girdling with 100% and 40% mortality recorded after a 100% winter and spring girdle, respectively.2.Tree vitality (leaf chlorophyll fluorescence, leaf chlorophyll content, crown leaf yellowing, nitrogen content) and growth (girth increment, die-back, number of epicormics above and below the girdle) of both tree species was not detrimentally affected following a 25% and 50% girdle.3.Epicormic production was more pronounced in English oaks compared to silver birch.4.Spring girdled oak typically had lower tree vitality and growth values than winter girdled trees indicating an influence of time of girdling. Such a response was not recorded in silver birch where time of girdling induced similar effects on tree growth and vitality.5.Growth and vitality measurements of surviving trees of both species were, in virtually all cases, statistically comparable with non-girdled trees by the end of the third growing season. Such a result indicates girdling >50% influences growth and vitality of both English oak and silver birch for three years. © 2015 Elsevier GmbH.
Chappelka A.H.,Auburn University |
Loewenstein E.F.,Auburn University |
Somers G.L.,Auburn University |
Keever G.J.,Auburn University |
Martin N.A.,Bartlett Tree Research Laboratories
Arboriculture and Urban Forestry | Year: 2015
Trees on the campus of Auburn University (Auburn, Alabama, U.S.) were used to test the efficiency of different crew sizes in conducting a 100% tree inventory. Seventy trees were randomly sampled at-large from a previously conducted 100% inventory (7,345 trees) on the Auburn University campus. Different crews consisting of one, two, or three individuals collected and recorded data using a GPS unit that timestamped the initiation and completion of data collection for each tree. The average time spent per tree was then calculated. Crews visited separate trees each time so there would be no overlap or bias. Each tree sampled was visited by all three crew sizes at different times. The relationship of sampling time per tree with increasing tree dbh was determined using regression analysis and subsequently likelihood ratio F tests. There was no statistical difference in the interval required to inventory a tree as dbh approached 0 (intercept, fixed time) for a two- and three-person crew, but the set-up (fixed) time for a one-person crew was significantly greater (approx. 2x) irrespective of dbh. The time interval it takes to inventory each tree increased with increasing dbh; however, the rate of change was significantly less for a three-person crew compared with the other crew sizes. Based on these results, the number and relative sizes (dbh) of trees to be inventoried must be considered when determining optimal crew size. ©2015 International Society of Arboriculture.
Grabosky J.C.,Rutgers University |
Thomas Smiley E.,Bartlett Tree Research Laboratories |
Thomas Smiley E.,Clemson University |
Dahle G.A.,Rutgers University
Arboriculture and Urban Forestry | Year: 2011
Root damage to infrastructure is common in the urban environment. Many problems could be avoided if more were known about tree root growth patterns and the forces involved. This study looks at the growth symmetry and forces from four roots to aid in the development of a computer model. Two primary roots, each from two trees, that were growing between two foam layers under pavement for 10 years were harvested and sectioned to measure radial growth symmetry to assist in the development of a computer simulation of root growth under pavement. The indentations in the foam created by the root growth were replicated using a universal loading press to estimate the radial growth pressure. Root growth was offset upward when close to the tree trunk, but shifted to a downward offset within 1 m. from the trunk. Load penetration testing of the foam suggested a minimal load of 0.35-0.40 MPa to replicate the foam deformation. © 2011 International Society of Arboriculture.
Fite K.,Bartlett Tree Research Laboratories |
Smiley E.T.,Bartlett Tree Research Laboratories |
McIntyre J.,Clemson University |
Wells C.E.,Clemson University
Arboriculture and Urban Forestry | Year: 2011
Researchers investigated the effects of a soil decompaction and amendment process (AFM) and its individual components (air tillage, fertilizer, and mulch) on soil properties at four urban sites: Anderson, South Carolina; Boston, Massachusetts; Myrtle Beach, South Carolina; and Pittsburgh, Pennsylvania, USA At each site, 50 red maples (Acer rubrum) were growing on compacted and/or nutrient-poor soils whose pre-treatment bulk densities ranged from 1.14 to 1.74 g/cm 3. Treatments were applied in the autumn and winter of 2005-2006, and measurements were taken through the end of 2008. The AFM treatment significantly reduced soil strength relative to control at all sites in 2006. There were significant treatment-location interactions in all years, with higher bulk density sites (Anderson and Myrtle Beach) showing the greatest magnitude and duration of response. The AFM and mulch treatments generally increased soil organic matter content, while air tillage alone significantly lowered soil organic matter content in Pittsburgh. At most sites, the AFM treatment was more effective than surface fertilizer application at improving soil fertility. AFM and mulched plots had significantly higher soil water content than other plots during periods of summer drought. Overall, AFM was effective in improving soils beneath established trees, and mulching was the most beneficial of the individual treatments. © 2011 International Society of Arboriculture.