Table of Contents Wayne A. Geyer, Keith D. Lynch, and Charles J. Barden Rocky Mountain Juniper Seed Source Test in Western Kansas, U.S. .................................................................... 325 Abstract. Twenty-six sources of Rocky Mountain juniper (Juniperus scopulorum Sarg.) were established as a provenance test near Colby, Kansas, U.S. in 1980. Height, diameter, survival, number of stems, crown density, branch angle, and vigor were evaluated with analysis of variance, cluster analysis, simple correlation, and regression analysis techniques. Source differences were found. Total height at 23 years ranged from 3.6 to 5.4 m (11.9 to 17.8 ſt), diameter breast height (dbh) ranged from 5.6 to 10.4 cm (2.2 to 4.2 in), and survival from 10% to 100%. Height growth was weakly related to geo- graphic variables, but dbh was related to latitude, longitude, and elevation. Selection of fast-growing sources may begin at 5 years aſter field planting. Key Words. Growth Characteristics; Juniper; Juniperus scopulorum; Rocky Mountain Juniper; Seed Sources. Oliver Bühler, Palle Kristoffersen, and Søren Ugilt Larsen Growth of Street Trees in Copenhagen With Emphasis on the Effect of Different Establishment Concepts ...................................................................... 330 Absrtact: Limited rooting space is considered a major problem for growth of street trees. Different approaches to extend the soil volume accessible to roots have been implemented in Copenhagen, Denmark, during the last 15 years. The presented survey investigates growth and vitality of trees planted in 1) structural, load-bearing soil; 2) sand-based load-bearing soil; and 3) so-called super planting pits and trees planted in conventional planting pits. The trees were either street trees or situated on paved squares. The results provide evidence that vitality of recently established street trees in Copenhagen generally is on an acceptable level. Furthermore, tree growth in both of the load-bearing materials allowing for root growth was found to be comparable to tree growth in conventional planting pits, and those methods are therefore considered applicable at sites where con- ventional pits cannot be established. However, tree growth in super planting pits was superior to any of the other methods both in regard to growth rates and vitality. This method is therefore recommended wherever space for large planting pits with open surfaces can be made available. Growth of trees planted in conventional pits varied considerably, reflecting the broad range of different conditions the term "conventional planting" pit covers. Key Words. Acer; Load-Bearing Soils; Planting Pit Design; Platanus; Populus; Road Foundations; Rooting Volume; Sand Mix; Stem Increment; Stone Matrix; Structural Soils; Tilia; Tree Growth; Urban Trees. Edward F. Gilman and Gary W. Knox Emerald Ash Borer (Agrilus planipennis) Density and Canopy Dieback in Three North American Ash Species ...................................................................................................................... 338 Abstract. Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), a phloem-feeding insect native to Asia, was identi- fied in 2002 as the cause of widespread ash (Fraxinus) mortality in southeast Michigan, U.S. and Windsor, Ontario, Canada. Little information about A. planipennis is available from its native range and it was not known whether this invasive pest would exhibit a preference for a par- ticular North American ash species. We monitored A. planipennis density and canopy condition on green ash (F. pennsylvanica) and white ash (F. americana) street trees in four neighbor-hoods and on white and blue ash (F. quadrangulata) trees in two woodlots in southeast Michigan. Green ash street trees had significantly more canopy dieback and higher A. planipennis densities than white ash trees growing in the same neigh- borhood. Density increased by two- to fourfold in both species over a 3-year period. Canopy dieback increased linearly from 2002 to 2005 as A. planipennis density increased (R2 =0.70). In each of the woodlots, A. planipennis densities were significantly higher on white ash trees than blue ash trees. Woodpecker predation occurred in all sites and accounted for 35% of the A. planipennis that developed on trees we surveyed. Results indicate that surveys for A. planipennis detection in areas with multiple ash species should focus on the relatively preferred species. Key Words. Blue Ash; Emerald Ash Borer; Fraxinus; Green Ash; Host Preference; Insect Survey; Invasive Pest; White Ash; Woodpecker. John Ball, Sarah Mason, Aaron Kiesz, Dan McCormick, and Craig Brown Assessing the Hazard of Emerald Ash Borer and Other Exotic Stressors to Community Forests ..................... 350 Abstract. Exotic stressors such as emerald ash borer are an increasing concern to many communities across North America. One means of assess- ing the hazard these stressors may represent to a community's publicly managed trees is through an inventory of their street trees. The South Dakota Division of Resource Conservation and Forestry conducted street tree inventories in selected communities across the state and, from these data, have placed communities into stability categories based on the percentage of full stocking that each genera represents within the street tree popula- tion. The majority of surveyed communities are in the low stability category as a result of the dominance of green ash in their street tree populations. Key Words. Agrilus planipennis; Emerald Ash Borer; Species Diversity; Stability; Street Tree Inventories; Street Trees. ©2007 | International Society of Arboriculture | ISSN:1935-5297
September 2007
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