3A Public Hearing 2008 0122 - Laserfiche WebLink

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Davidon Homes, July 2007 HortScience, Inc. Tree Report, Woodside Apartments Page 3 .~..., Purple leaf plums had performed moderately well at the site. Most were below the 6" threshold for inclusion in the survey, however those that were surveyed typically had fair form and structure. Many were growing amongst, and being shaded by adjacent coast redwoods, producing trees with supressed forms and/or leans. Table 1. Tree condition 8 frequency of occurrence. Woodside Apartments, San Leandro Common Name Scientific Name Condition Rating No. of Fair Good trees (3) (4.5) Italian alder Alnus rhombifolia 1 - 1 Sweet gum Liquidambar sfyraciflua 11 11 22 .African fem pine Podocarpus gracilor 1 - 1 Purple leaf plum Prunus cerasifera 'Atropurpurea' 5 1 6 Black locust Robinia pseudoacacia 1 - 1 Coast redwood Sequoia sempervirens 2 10 12 Total 21 22 43 49% 51% 100% Suitability for Preservation Before evaluating the impacts that will occur during development, it is important to consider the quality of the tree resource itself, and the potential for individual trees to function well over an extended length of time. Trees that are preserved on development sites must be carefully selected to make sure that they may survive development impacts, adapt to a new environment and perform well in the landscape. For trees growing in open fields, away from areas where people and property are present, structural defects and/or poor health presents a low risk of damage or injury if they fail. However, we must be concerned about safety in use areas. Therefore, where development encroaches into existing plantings, we must consider their structural stability as well as their potential to grow and thrive in a new environment. Where development will not occur, the normal life cycles of decline, structural failure and death should be allowed to continue. Evaluation of suitability for preservation considers several factors: Tree health Healthy, vigorous trees are better able to tolerate impacts such as root injury, demolition of existing structures, changes in soil grade and moisture, and soil compaction than are non-vigorous trees. Structural integrity Trees with significant amounts of wood decay and other structural defects that cannot be corrected are likely to fail. Such trees should not be preserved in areas where damage to people or property is likely. Species response There is a wide variation in the response of individual species to construction impacts and changes in the environment. In our experience, for example sweet gums are intolerant of root loss. In contrast, coast redwoods have a good tolerance to site disturbance.