RES 2025054 - Laserfiche WebLink

Tree replacement in WUI areas should consider the concept of "right tree, right place, right reason" for each site. Right tree, right place emphasizes planting tree species compatible with the region they are growing in and having adequate space to develop without creating hazardous conditions. Trees that are incompatible with the site they are planted in are more likely to be in poor health, have greater maintenance costs, and require early removal (Arbor Day Foundation 2024). In the WUI areas of the City, the "right tree, right place, right reason" includes adequate spacing between newly planted trees and existing vegetation. As noted in the Livermore Pleasanton Fire Department's vegetation management guidelines, there should be 10 to 40 feet of space between tree crowns, depending on the slope. Planting replacement trees should not only consider whether the species is appropriate for the property but also if the tree will have adequate space between nearby vegetation to minimize the risk of fire transitioning into the tree crown. SubAppendix C contains a list of tree species appropriate for WUI areas in the City of Pleasanton. As a final note, it is not appropriate to replace every tree removed with a new tree in the same location. Poor replanting sites include locations within 10 feet of a structure, within 5 feet of an underground utility line, within 25 feet of an overhead electrical line, and in locations with inadequate spacing between the crowns of the existing mature trees. Replacement trees should be relocated to a more appropriate site in these situations. Watering When establishing new trees, deep, periodic (weekly) watering ensures water slowly percolates to at least the first 12 inches of soil, allowing roots to establish into the landscape. Once a tree is established in approximately the first three years after planting, supplemental watering is only necessary during extreme heat or prolonged drought periods. Deep watering during the establishment period encourages root growth beyond the surface, which would occur if shallow or broadcast irrigation was used to establish the tree. Deep watering is a best practice to establish the root system of newly planted trees into the landscape, helping to reduce the likelihood of future storm- or wind - related failure. When extreme heat or drought is experienced, mature trees may benefit from supplemental watering once per month around the dripline. During predicted high heat events, dry periods, and drought, trees with shallow roots struggle to intake enough water from the top of the soil, which dries out first (Davey Research, 2016). Deep watering stimulates trees to produce broad and deep root systems, resulting in trees that are better able to survive drought, are more solidly anchored, and can withstand significant winds. This technique also uses less water, which provides greater security so that the tree can survive through extended drought conditions where water restrictions might be in place. Keeping trees in the wildfire hazard area sufficiently irrigated decreases the risk of ignitions and/or extreme fire behavior. Staffing The City of Pleasanton has roughly 40 staff members that interact with trees, being utilized across a range of urban forest tasks, including planting, establishment care, pruning, removals, and tree debris cleanup. However, tree maintenance is only a small portion of their workloads. The majority (80 to 90%) of the workloads for Park staff consist of non -tree -related park maintenance duties. In reality, the City only has the equivalent of 4.6 full-time staff working on urban forest management and utilizes a tree maintenance contractor to accomplish the majority of the public street tree pruning and tree removal work. Accomplishing the tree maintenance standards above requires adequate staffing to perform the recommended tree maintenance activities. Some of the recommended maintenance activities are already being done as part of the City's routine tree maintenance. The tree maintenance contractor already trims street trees overhanging public streets to create 14 feet of clearance above the roadway, and City staff identifies and schedules the removal of dead trees in a timely manner. Some of the recommended maintenance activities can be incorporated into the existing tree maintenance programs but will require modifying the standards used by City staff and the tree APPENDIX A -WILDFIRE 23 of 219