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CITY OF PLEASANTON URBAN FOREST MASTER PLAN | 133 STATUS OF THE URBAN FOREST PUBLIC AND PRIVATE TREES Table 2-9. DSH Distributions in the Pleasanton Inventory Sustainability goal: Age classes of trees are sufficiently distributed to ensure environmental benefits continue Age Category DSH (inches) Number of Trees % of inventory Recommended Percentage of Tree Inventory Immature 1–6 6,564 28%40% Young 7–18 12,144 51%30% Middle-aged 19–24 2,740 12%20% Mature 25+2,219 9%10% Source: City of Pleasanton Tree Inventory (Dudek 2024); Richards 1983. 2.7 Tree Condition and Relative Performance Index Trees that are healthy with good trunk and branch structure generally have a lower risk of failure and contribute to a safer City. To determine tree condition, arborists conducting the City’s tree inventory rated trees on a scale based on visible characteristics of health condition and canopy structure (Table 2-10). Pursuant to the Council of Tree and Landscape Appraisers’ “Guide for Plant Appraisal,” tree health and structure were evaluated with respect to five distinct tree components: roots, trunk, scaffold branches, small branches, and foliage. Each component of the tree was assessed with regard to health factors such as insect or pathogen damage, mechanical damage, presence of decay, presence of wilted or dead leaves, and wound closure. Tree health and structure were graded as good, fair, poor, critical, or dead, with good representing no apparent problems and dead representing a dying or dead tree. Good condition trees exhibit acceptable vigor, healthy foliage, and adequate structure and lack any major maladies. Fair condition trees typically have few maladies but declining vigor. Trees in poor and critical condition exhibit declining vigor, unhealthy foliage, poor branch structure, and excessive lean. This method of tree condition rating is comprehensive and results in ratings that are useful for determining the status of trees based on common urban forestry standards.