05-06-2025 PK Agenda - Laserfiche WebLink

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Davey Resource Group, Inc. Tree Inventory Analysis & Maintenance Strategy Page 8 ●Trees in Poor condition not recommended for removal should be maintained to reduce risk associated with defects and should be routinely monitored for further decline that would necessitate removal. ●Condition ratings can be improved over time by instituting proactive maintenance cycles such as routine pruning and young tree training. All tree pruning should follow ANSI A300 (Clause 5) guidelines. RELATIVE AGE DISTRIBUTION Analysis of a tree population’s relative age distribution can be performed by assigning age classes to the diameter of trees. While actual tree age cannot be determined by diameter alone, this industry standard method provides an estimate of the approximate age distribution of the inventoried tree population. Since trees at different stages of development need different types and frequencies of maintenance, age distribution can help inform management needs and decisions. The size classes (left) are based on the industry-recognized ideal relative age distribution, which holds that the largest proportion of the inventoried tree population (40%) should be young trees, smaller portions should be established and maturing trees (30% and 20%, respectively), and the smallest proportion (10%) should be mature trees. Figure 6 compares the age distribution of the tree population to standard industry recommendation. Overall, Orono’s street trees are trending toward the industry recommended age distribution, with a surplus of established trees (46%), moderate numbers of young and mature trees (38% and 6%, respectively), and fewer maturing trees (11%). In parks, there is an underrepresentation of young and maturing trees (35% and 16% versus the 40% and 20% recommendation) and a surplus of established trees (39% versus the 30% recommendation). Figure 7 compares tree condition ratings across the relative age classes for inventoried trees. Trees across all age classes are generally in Fair condition. In general, trees in the young age class are more likely to be in Good condition, while maturing and mature age classes are more likely to have trees in Poor condition. RELATIVE AGE RECOMMENDATIONS ●The city of Orono’s park and street trees are young. Orono should focus on tree pruning and proactive care for these young and established trees, and a maintenance plan should be implemented to ensure that the young and established trees can mature while retaining good health and proper form. ●A large proportion of street trees are young or established (53% of street trees and 28% of park trees). A young tree training cycle should be instituted to structurally prune these younger trees to ensure good form and improve health as they mature. ●Street tree planting is currently sufficient to maintain the recommended age distribution. However, sustained planting efforts over time will be necessary to retain this age distribution. Age/Size Classes Young: 0-8 inches diameter at standard height (DSH), as measured 4.5’ above the ground Established: 9-17 inches DSH Maturing: 18-24 inches DSH Mature: 25+ inches DSH 20