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CITY OF PLEASANTON URBAN FOREST MASTER PLAN | 23 <br />STATUS OF THE URBAN FOREST <br />1.4.2 Tree Inventory <br />The City of Pleasanton’s most recent tree inventory was <br />collected between 2023 and 2024 by Dudek. The current <br />inventory was updated from an older inventory, originally <br />collected by West Coast Arborists, Inc. (WCA), and includes <br />23,722 trees and 3,976 plantable vacant sites (three square <br />feet and greater in size) in streets and parks. Vacant sites <br />were considered plantable if they were labeled as a vacant <br />site or stump by inventory collection field staff and had a <br />tree well or parkway size equal to or greater than three feet. <br />The City’s current stocking rate is 85.6%, which is calculated <br />by dividing the total number of existing trees by the total <br />number of plantable sites on public land. The stocking rate <br />does not include potential sites that need modification to be <br />viable or sites that are not captured in current inventory data. <br />The variety of different tree species within the urban forest is <br />known as species diversity. Another important related factor <br />is species evenness, which is the relative abundances of <br />each species. Species diversity and evenness help provide <br />resiliency to pest and pathogen infestations through the variety <br />of different biological and physiological characteristics of each <br />tree species. If one tree species is especially susceptible to <br />a particular pest, having a variation of species in the city that <br />are more resistant or unaffected by the pest ensures that the <br />overall urban forest will survive. Pleasanton’s 23,722 trees <br />are composed of 113 genera and 250 species. According to <br />a recent study looking at the diversity of urban forests across <br />multiple California cities, 250 is a typical number of species for <br />a City with a size and climate similar to Pleasanton’s (Love et al., <br />2022). The top 10 genera and species in Pleasanton are shown <br />in Figures 1-5 and 1-6. The species diversity sustainability goals <br />are as follows: <br /> „Sustainability Goal (Genus): No genus represents more than 20% of inventory. <br /> „Sustainability Goal (Species): No species <br />represents more than 10% of inventory. <br />An exception to the genus and species goals above are <br />for native species such as oaks, which may exceed the <br />recommended sustainability goals. The City and community <br />have put a high value on native species for the additional <br />benefits they provide like habitat for wildlife. The oak genus <br />Quercus currently makes up just over 20% of the inventory <br />and the two most common oak species (coast live oak <br />and valley oak) within the City make up 9.4% and 7.2%, <br />respectively, of the overall species in the inventory. Another <br />exception to consider for the City are tree species that <br />already have a proven history of resiliency in Pleasanton’s <br />urban landscape, which might include species that have <br />already survived extreme heat and drought periods, <br />recovered from pest infestations, or that have held up to <br />root pruning.