Arboriculture & Urban Forestry 34(3): May 2008 Master Plan are suitable for development. However, the recom- mended 18 m2 green area per capita seems not to be enough to maintain ecological balance and organization of the green spaces in the 2020 plan seems to lack a theoretical basis, or a holistic framework, at different scales. From this perspective, we pro- pose that Hanoi should set aside an extra green area from 6842 to 10,228 ha, and that the 2020 Hanoi green structure plan at regional, city and neighborhood scales includes three green wedges, one green belt, various parks and other green ways to create a green network ecologically more effective than the sum of the individual green spaces. This green structure and the com- bined data approaches used here will form a base for building a garden city or an eco-city in the future. (Urban Forestry and Urban Greening 2008. 7(1):25–40) TREE FAILURE FOLLOWING A WINDSTORM IN BREWSTER, MASSACHUSETTS, USA Brian Kane While there are many ex post facto studies of tree failures due to catastrophic storms, relatively few have considered the effect of defects, and even fewer have explored the effect of tree main- tenance, on the likelihood of failure. In light of the heightened climate of litigation in the United States, and the complexity of reliably predicting tree failure, additional studies are justified. A catastrophic windstorm in December 2005 on Cape Cod in Mas- sachusetts, USA, provided an opportunity to study how struc- tural defects and maintenance history affect the likelihood of tree failure. Species, height, diameter at breast height (DBH), the presence of defects, and whether trees had been pruned or nearby trees removed were recorded on trees at campsites in a park affected by the storm. The percentage of trees that failed varied among species, and evergreens failed more frequently than de- ciduous trees, which were leafless at the time of the storm. Large trees were more likely to fail than smaller trees, although this was not true of all species. The defects were more common on standing trees and trunk failures than root failures. Pruning trees had little effect on the failure, but removing trees increased the likelihood of root failure. The results are discussed in the context 205 of managing tree risk. (Urban Forestry and Urban Greening 2008. 7(1):15–23) PREDICTING OPPORTUNITIES FOR GREENING AND PATTERNS OF VEGETATION ON PRIVATE URBAN LANDS Austin Troy, J. Grove, J. O’Neil-Dunne, S. Pickett, and M. Cadenasso This paper examines predictors of vegetative cover on private lands in Baltimore, Maryland. Using high-resolution spatial data, we generated two measures: “possible stewardship,” which is the proportion of private land that does not have built structures on it and hence has the possibility of supporting vegetation, and “realized stewardship,” which is the proportion of possible stew- ardship land upon which vegetation is growing. These measures were calculated at the parcel level and averaged by US Census block group. Realized stewardship was further defined by pro- portion of tree canopy and grass. Expenditures on yard supplies and services, available by block group, were used to help un- derstand where vegetation condition appears to be the result of current activity, past legacies, or abandonment. PRIZM™ mar- ket segmentation data were tested as categorical predictors of possible and realized stewardship and yard expenditures. PRIZM™ segmentations are hierarchically clustered into 5, 15, and 62 categories, which correspond to population density, so- cial stratification (income and education), and lifestyle clusters, respectively. We found that PRIZM 15 best predicted variation in possible stewardship and PRIZM 62 best predicted variation in realized stewardship. These results were further analyzed by regressing each dependent variable against a set of continuous variables reflective of each of the three PRIZM groupings. Hous- ing age, vacancy, and population density were found to be criti- cal determinants of both stewardship metrics. A number of life- style factors, such as average family size, marriage rates, and percentage of single-family detached homes, were strongly re- lated to realized stewardship. The percentage of African Ameri- cans by block group was positively related to realized steward- ship but negatively related to yard expenditures. (Environmental Management 2007. 40(3):394–412) ©2008 International Society of Arboriculture
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