ARBORICULTURE ARBORICULTU & CONTENTS URBAN FORESTRY Volume 36, Issue 6, November 2010 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) www.isa-arbor.com Denise Johnstone, Michael Tausz, Gregory Moore, and Marc Nicolas Quantifying Wood Decay in Sydney Bluegum (Eucalyptus saligna) Trees ..................................... 243 Abstract. The evaluation of decayed wood in a tree is essential for tree risk assessment in arboriculture. It is not feasible in prac- tice to measure the amount of wood decay in all the wood of every tree. Therefore, the capacity of a single measurement taken in cross-section to approximate the volume of decay in the wood of a whole tree is the focus of this study. The volume of wood decay in Eucalyptus saligna trees was estimated post harvest by measuring the whole tree wood density of 36 trees. Linear, logarith- mic, and multiple regression statistical models were used to examine whether whole tree wood density data could be correlated with three ways of directly measuring wood decay in a single cross-section, two prior to tree felling and one post felling method. The decay estimation techniques were measured in cross-section—a Picus® Sonic Tomograph system, an IML-Resi system, and a visual method. In this study the Resi System for estimating wood decay showed a correlation with whole tree wood density in the entire tree whereas the Picus system and the visual method did not show any statistical correlation with whole tree wood density. Key Words. Eucalypts; Hazard Trees; Picus® Sonic Tomograph; Resi; Resistograph; Tree Failure; Tree Risk Analysis; Wood Decay. Wendy McWilliam, Paul Eagles, Mark Seasons, and Robert Brown Assessing the Degradation Effects of Local Residents on Urban Forests in Ontario, Canada ..... 253 Abstract. Urban forests provide essential social, ecological, and economic functions in support of their communities; however, surveys indi- cate adjacent residents conduct activities within their yards and the adjacent public forest edge that degrade these systems. Local governments rely on boundary-focused passive management and/or active management to limit impacts. Encroachment results from various boundary treatments; however, it is not known whether encroachment represents a substantial source of degradation within Ontario, Canada, munici- pal forests. To evaluate this, percentage cover of encroachment impacts adjacent to 186 homes within 40 forests of six Southern Ontario municipalities was surveyed. The results indicated degradation resulting from encroachment was substantial. Encroachment occurred in highly valued and sensitive ecosystems, and during sensitive time periods. This was highly prevalent and covered a substantial proportion of the forest edge. Some encroachment behaviors were particularly harmful, resulting in the loss of significant forest area to residential land uses. Furthermore, encroachments remained over long periods. The small sizes and convoluted shapes of urban forests leave them vulnerable to these impacts. Prevailing municipal strategies are insufficient to protect these systems from encroachment. To ensure their long term pro- tection, municipalities and their communities need to substantially increase their commitment and resources for addressing encroachment. Key Words. Adjacent Land Use; Green Infrastructure; Greenspaces; Planning and Management; Residential Encroachment; Urban Forest Ecosystems; Urban Forest Edges. Henrik Sjöman, Anders Busse Nielsen, Stephan Pauleit, and Mats Olsson Habitat Studies Identifying Potential Trees for Urban Paved Environments: A Case Study from Qinling Mt., China ................................................................................................................ 261 Abstract. Trees in urban paved environments are highly exposed to heat, low air humidity, periods of critical water stress, high soil lime content and soil pH, limited soil volume, pollutants, and de-icing salts. Combined with the challenges of climate change and the threat of disease and pest infestations, this has led to considerable and persistent arguments for using a more varied range of trees, including stress-tolerant species, at urban paved sites. Extensive fieldwork was carried out in the Qinling Mountains, China, in a search for tree species suitable for urban paved sites in northern parts of central Europe and in adjoining milder parts of north- ern Europe (CNE-region), where tree species are exposed to seasonally dry and harsh conditions. The study identified habitats in the Qinling Mountain range that are similar to those at sites in paved environments, and analyzed the growth and performance of different tree species in these habitats. A total of 25 tree species representing 21 genera were found, of which 14 species were identified as spe- cialist colonizers of warm, dry south-facing slopes where site conditions are similar to those in paved environments of the CNE-region. Key Words: Habitat Studies; Selection; Site-Adapted Species Use; Urban Paved Sites; Woody Species. ©2010 | International Society of Arboriculture | ISSN:1935-5297
November 2010
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