September 19, 2023
City Council
URBAN FOREST PRUNING MANAGEMENT
1 Why we prune trees
To reduce the risk, improve or maintain health, develop desired structure and appearance, prevent interference with built environment and other specific objectives. 2 Pruning Systems
Natural: informal style used to retain and promote the characteristic form of the species or cultivar in its current location, often with essential variations needed to avoid conflicts. 3 Topiary
Natural
Natural Pruning Systems
Grid Pruning (up to 25%)
Large Scale Pruning (Risk Mitigation Pruning) (More than 25%) All Pruning systems performed in the city are within ISA Standards, ANSI A300 and Best Management Practices 4 Grid Pruning
Objective: Remove diseased, decayed, dead and broken branches. Provide sidewalk and road clearance.
Up to 25% of live crown
Minimal stress
Every 4 years
All species except for Chinese Elm
In compliance with ISA, ANSI A300 and BMP
5 Grid Pruning
Before
6 After
Grid Pruning
7 *WCA have Certified Tree Workers/Arborists performing trimming/removals at all times.
Grid Pruning
8 Grid Pruning
9 Chinese Elm
Species Profile:
Branch strength: Medium Weak/Medium
Prone to Sudden Limb Failure (Summer)
Rapid crown regeneration
Architecture: Twisted, irregular
Emergency Call Outs for FY 2016/2017: 169
10 Risk Mitigation Pruning (Elm Trees)
Reduce the likelihood of whole tree and/or branch failure.
Crown Reduction: removal of the larger of two or more branches, stems or codominant stems to a live lateral branch or stem, typically one-third the diameter of the stem being removed. Also, decreases wind load, leverage arm and total crown weight. (In compliance with ISA, ANSI A300 and BMP) 11 Risk Mitigation Pruning (Elm Trees)
12 Elm Architecture
Due to its unique architecture, regardless of the technique used, it is hard to preserve a defined shape, while effectively reducing crown for Risk Mitigation. 13 Elm Architecture
14 Elm Architecture
15 Benefits
The overall amount of call outs, due to sudden limb drop in the City of Fullerton, has been reduced around 95% through the years since implemented. 16 Year
Elm Emergency call outs
16-17
169
17-18
106
18-19
79 19-20
72 20-21
8 21-22
19 22-23
10 Conclusion
Risk Mitigation Pruning (Crown Reduction) to mitigate the risk of whole tree, stem and branch failure has been proven to effectively reduce the likelihood of failure, and given the rapid ability that this particular species has to regenerate its own crown, is the best way to preserve optimal tree cover, while reducing failures, emergencies and damage to structures. 17 3/21/21 Fullerton, Ca