TO: COMMUNITY AND HUMAN SERVICES COMMISSION
FROM: JEREMY SWAN, COMMUNITY SERVICES DIRECTOR
DATE: MAY 7, 2025
SUBJECT:
Title
URBAN FOREST UPDATE - 2024
Body
SUMMARY
The Community Services Department is charged with the maintenance and care of the urban forest, including all planting, trimming, removal, and, when necessary, treatment of all City trees. Currently, the City’s urban forest is comprised of over 24,500 trees of over 300 unique species, with an estimated value of over $96.8 million. Each year Community Services staff outline a maintenance plan for the urban forest based on the Tree Policies and Guidelines Manual and best practices of the industry. As staff works through the annual work plan, any changes to the local and regional urban forest are noted, and adjustments to the annual work plan are made as needed. This report serves as an update on the urban forest condition and activities over the past year.
RECOMMENDATION
Recommended Action
Staff recommends the Community and Human Services Commission receive and file the report on the urban forest condition and activities for 2024.
Body
ALTERNATIVE TO RECOMMENDATION
In addition to the recommendation, there is the following alternative:
• Refer the matter back to staff for additional information.
FINANCIAL REVIEW
The staff cost to prepare this report is estimated at $1,450 and is included in the operating budget of the Community Services Department.
ANALYSIS
The Community Services Department is charged with the maintenance and care of the urban forest. Under the direction of the Community Services Director, the Community Services Manager oversees the day-to-day operations of urban forest maintenance. Staffing for urban forest maintenance consists of one full-time Arborist and one full-time Maintenance Craftsworker I. The City Arborist oversees maintenance activities, makes inspections, and plans for the future of the urban forest. Due to the magnitude of the urban forest, the City outsources urban forest maintenance activities, and the City Arborist works closely with the contractor to ensure that the urban forest is maintained to City standards. West Coast Arborists, Inc. (WCA) has been the City’s urban forest maintenance contractor for over 15 years.
CURRENT STATUS OF THE URBAN FOREST
As of April 2025, the urban forest consists of approximately 24,500 trees, with a total value of approximately $96.8 million. Tree value is based on size, location, and species rating.
Tree Count over Time
About ten years ago, the urban forest was home to approximately 27,000 trees. Tree removals were primarily determined by the budget, and trees were removed as funding allowed. This meant that many dead, diseased, or hazardous trees were left in the ground until removal funding was available. Tree planting was not mandatory, and funding was limited to 200 trees per year. Additionally, during this time, little outreach was conducted to encourage reforestation.
In 2014, the Liquidambar mitigation plan was approved to begin removing liquidambars that showed signs of Xylella. During this time, the trees faced several years of drought and water restrictions, which greatly affected the rate of removal. Mandatory replanting began in 2014. Although trees were planted at the rate they were removed, water restrictions led to property owners not watering the newly planted trees. This led to a higher failure rate of young trees.
During 2018-2021, the reforestation program was funded through grant funds, which increased the number of tree plantings, and leveled removals versus plantings. In 2019, Invasive Shot Hole Borer was identified in the City, which led to increased removals of affected species. In 2020, during COVID restrictions, there was limited interest in tree plantings.
The significant decline in tree count in 2022 and 2023 is due to the Windstorm of 2022. However, in 2023, the number of tree plantings increased over the number of trees removed, which helped counter a significant decline in the urban forest.
The changes to the urban forest tree count in 2024 can be attributed to the Towne Avenue Improvement Project. Tree removals that occurred in February 2024 were accounted for, but plantings have yet to be inventoried because the project is not yet completed. Once the new trees are entered into the tree inventory, the City’s tree count will increase by approximately 130 trees. During this period, staff worked with WCA to remove from the inventory plantings that should not be considered trees (e.g. yucca and certain species of small palms), further reducing inventory. We have also seen an increase in properties that prefer to plant trees on private property rather than in the City right-of-way. Finally, WCA is behind on tree planting for this season, due to windstorm cleanup and pushing to complete grid trimming before nesting season.
It should also be noted that the City lost approximately 100 trees during the windstorm in January 2025. Replanting of most of these trees will be deferred until fall.
Below is a chart showing the number of trees in the urban forest over the past 13 years.
As the urban forest becomes healthier and potentially high-risk trees are slowly removed, staff will increase reforestation outreach with a focus on planting “the right tree in the right place.” Outreach will continue on the proper watering of trees to educate residents on proper watering during different weather conditions. Healthier trees lead to a healthier, sustainable urban forest.
Tree Diversity
The types of trees in the urban forest greatly affect the benefits produced, maintenance activities, and the urban forest budget. Based on tree inventory data, Claremont’s urban forest contains over 300 unique species, the top ten species being:
Top 10 Species
|
Percentage of Urban Forest |
Species |
|
8.3% |
CRAPE MYRTLE |
|
8.0% |
COAST LIVE OAK |
|
5.9% |
CALIFORNIA SYCAMORE |
|
4.0% |
JACARANDA |
|
3.6% |
HOLLY OAK |
|
3.3% |
CANARY ISLAND PINE |
|
2.9% |
CHINESE PISTACHE |
|
2.8% |
AMERICAN SWEETGUM |
|
2.4% |
OLIVE |
|
2.0% |
MAIDENHAIR |
Size and Age Distribution
An urban forest with a wide age range offers a continuous flow of benefits and allows for better planning of urban forest activities. A tree’s age is determined by its diameter at breast height (DBH), or 4.5’ from the base of the tree. Below is the City’s current DBH distribution compared to the ideal distribution according to the U.S. Forest Service:
|
DBH (inches) |
Total |
Current Percentage |
Ideal Percentage |
|
0-6 |
5871 |
23.9% |
40% |
|
7-12 |
6,266 |
25.5% |
25% |
|
13-18 |
6,295 |
25.7% |
15% |
|
19-24 |
2,547 |
10.4% |
10% |
|
25-30 |
2,710 |
11.0% |
6% |
|
31+ |
851 |
3.5% |
4% |
|
Total: |
24,540 |
|
|
Because the City’s urban forest age distribution is inconsistent with the ideal, the City should continue replacing trees annually to reach the ideal age distribution.
Geographical Distribution
Utilizing a geographic grid system allows staff to plan and budget for routine tree maintenance activities, including trimming and removals. Additionally, grids show where reforestation efforts should be focused. There are five geographical grids. Below is an overview of the number of City trees in each grid:
|
Grid |
Current Number of Trees |
2024 Number of Trees |
2023 Number of Trees |
|
1 |
4,519 |
4,588 |
4,558 |
|
2 |
5,061 |
5,109 |
5,097 |
|
3 |
5,982 |
6,241 |
6,249 |
|
4 |
4,869 |
4,932 |
5,072 |
|
5 |
4,109 |
4,146 |
4,428 |
|
Total: |
24,540 |
25,016 |
25,404 |
The City strives to replant all trees that were removed during the prior year, provided they are viable planting sites; however, reforestation is a partnership between property owners and the City. The Claremont Municipal Code requires property owners to water City trees; therefore, if a property owner does not want a new tree, a tree will not be planted because it will likely not be cared for.
Avian Activity
During this reporting cycle, no nesting birds were reported. WCA staff will continue to inspect for nesting activity during maintenance practices. Should they come across signs of nesting, a notice will be posted, and no work will be done until there is no evidence of nesting.
Urban Forest Highlights
Liquidambar Mitigation Program
Approximately 10 years ago, liquidambars began showing signs of Xylella dieback. Xylella fastidiosa is a non-curable disease that affects a tree’s vascular system. The only cure and prevention of further infection is removal of infected trees. When the program began, there were approximately 2,500 liquidambars in the City; currently, there are approximately 890. In years past, reported liquidambar numbers only included Liquidambar styraciflua (American sweetgums), as they seemed to be the most impacted variety. However, in recent years we have noted that other varieties are showing signs of Xylella dieback. The approximately 890 liquidambars remaining in the City include Liquidambar formosana and Liquidambar styraciflua ‘Rotundiloba.’
Each year, the City conducts an assessment of all liquidambars in the City. From this assessment, staff determines which trees require removal. Trees that present 75 percent or greater dieback and trees with dieback in branches greater than 6” in diameter are recommended for removal. Depending on available funding, the threshold for removal is adjusted. Last year, 18 liquidambars were removed, compared to 33 in 2023 and 45 in 2022. Although Xylella is still present in the City, it is not as prevalent as in years past. This is most likely due to increased watering and routine trimming. The healthier a tree is, the better its ability to fight off disease. Over the next few years, staff anticipates the impact of Xylella on liquidambars will continue to decrease, leading to fewer removals.
Invasive Shot Hole Borer
Invasive Shot Hole Borer (ISHB), once known as the Polyphagous Shot Hole Borer, posed a huge threat to the City’s sycamore and oak tree population. ISHB is an aggressive beetle that bores into trees and introduces a fungus that causes fusarium dieback, much like Xylella, and presents itself as pinholes in the trunk of the tree. In 2019, the City treated a large population of sycamore and oak trees with an experimental treatment. This treatment slowed the spread of the insect and infection in the City, but the City did lose some mature sycamores. Due to cost, the City did not continue with widespread treatment. Although ISHB activity is less prevalent in the City as in previous years, the City continues to monitor and treat as necessary. This change is likely due to increased watering and awareness. Fewer than five trees were removed due to ISHB in 2023, which is consistent with 2022. There were no sycamores removed due to ISHB in 2024.
Pine Bark Beetle
A new threat to the City’s urban forest is the Pine Bark Beetle, an aggressive and fast-moving insect that feeds on the cambium layer of a pine tree, causing the tree to die back rapidly. Pine Bark Beetle activity increases during the warmer months. Treatment is available, but usually by the time symptoms appear, the tree is too far in decline. The best mitigation practice is to remove an infected tree immediately to prevent further spread. In 2023, the City removed seven pine trees due to the Pine Bark Beetle, which is one more than in the previous year. There were no pines removed due to the Pine Bark Beetle in 2024.
Tree Policies and Guidelines Manual Update
In July 2023, the City Council entered into a professional services agreement with Dudek to review and revise the Tree Policies and Guidelines Manual. Since the adoption of the Manual in 1997, only minor changes have been made. These revisions have addressed climate change, monocultures, nursery stock challenges, and pest/disease treatments. Much has changed in the industry and the community over the past several years, most notably the ongoing drought, the Windstorm of 2022, and increased conflicts between trees and hardscape/infrastructure. Additionally, the move to plant more climate-appropriate species has become customary.
The Tree Committee approved the revised Manual in December 2024, and both the Community and Human Services Commission and City Council approved it in January 2025. The revision focused on six goals and objectives, including:
• Best Management Practices
• Tree Maintenance and Wildlife Protections
• Maintaining the Tree Canopy
• Removal Parameters
• Infrastructure Conflict Resolutions
• Communication, Transparency, and Procedure
Over the next year, staff will work to implement the six goals and objectives included in the Manual update.
Looking Ahead
The 2024-26 budget includes funding for a five-year grid trimming cycle. A five-year cycle is more in line with industry standards, will lead to a healthier urban forest, and will reduce City liability. More frequent trimming helps trees to adapt to the rigors of the urban environment, promotes healthy growth, reduces damage during storms, and reduces risk of failure and decay. The third year of the new five-year grid trimming cycle is complete, and the benefits of the more frequent trimming cycle can be seen throughout the City. There are lower frequencies of downed trees and branches, and fewer visibility/line-of-sight issues.
Reforestation efforts will ramp-up this year through new public outreach materials. In 2024, the City launched a new pilot program for reforestation yard signs. A yard sign containing a QR code with reforestation information is installed at each site as a visual representation of a new tree. Once the tree is planted, the sign is removed and reused. The City will also have new social media campaign material, revamped flyers, and other public outreach materials available in summer 2025.
As a means to ensure high-quality new trees, City staff has begun inspecting all nursery stock prior to planting. WCA will bring nursery stock to the City Yard for inspection, and any stock that is not in accordance with City standards will be rejected. WCA will return with new stock as needed until all nursery stock meets City standards.
Also coming this year is the City’s new notification procedure for non-emergency removals. Per the revised Tree Policies and Guidelines Manual, all non-emergency removals will be posted on the City’s website for a 15-day public objection period. Postings will occur on the 1st and 16th of each month, given there are recommended non-emergency removals. The new procedures include an automatic notification process, open to anyone that opts in by signing up via the City website or email. Anyone who has opted in will receive by email a notice that information has been posted on the website.
In April 2024, the City Council approved the 2024-26 City Council Priorities. One of the seven priorities is to “Preserve Our Natural, Cultural, and Historic Resources.” In support of this priority, one of the Council’s objectives is to review the City’s planning documents and the City’s current urban forest management practices to ensure consistency. The objective states:
Ensure that the City’s Sustainable City Plan, Urban Forest Management Plan, General Plan, Municipal Code, Tree Policies and Guidelines Manual, internal policies/procedures, and staff/contractor qualifications and instructions are all consistent with best urban forest practices and with one another, and are effective in preserving and expanding our City’s Urban Forest, both public and private.
This project will begin in late summer after implementing the approved revisions of the Tree Policies and Guidelines Manual.
Take-Aways
This year had dryer weather than in the past several years, which produced less growth, and we are seeing a slight increase in trees suffering from lack of water. Staff will work with property owners on the importance of tree watering and the great benefits trees provide.
Healthy, well-maintained trees are better equipped to fight off disease and infections, more so than stressed and declining trees. In addition, a healthy, well-maintained urban forest leads to fewer liability claims for property damaged by downed trees and branches. It is imperative that the City maintain a healthy urban forest, and as the City moves forward with urban forest maintenance, staff strive to maintain a quality urban forest with greater focus on responsible planting, proper young tree care, and sensible preservation of the aging forest.
CEQA REVIEW
This item is not subject to environmental review under the California Environmental Quality Act (CEQA).
COMMITTEE REVIEW
On April 30, 2025, the Tree Committee recommended that the Community and Human Services Commission receive and file this report. An excerpt from the draft minutes for the meeting is attached.
PUBLIC NOTICE PROCESS
The agenda and staff report for this item have been posted on the City website and distributed to interested parties. If you desire a copy, please contact the City Clerk’s Office.
The agenda and staff report for this item have been posted on the City website and distributed to interested parties. If you desire a paper copy, please contact the Community Services Department.
Submitted by: Prepared by:
Jeremy Swan Cari Dillman
Community Services Director Community Services Manager
Attachment:
Excerpt from the Draft 4-30-25 Tree Committee Special Meeting Minutes