- Author: Janet Hartin
Landscape trees provide shade, cool urban heat islands, reduce interior energy use and related costs, provide habitat for pollinators and wildlife, and beautify our communities. They also help clean our environment by absorbing carbon dioxide emitted by vehicles and other producers of fossil fuels.
Taking care of our urban trees is an important way to maximize these benefits. Unfortunately, their average lifespan in our cities is less than 1/4 of their potential due to poor selection and care. You can help enact change and increase the health, longevity and canopy coverage of our urban forests by encouraging your city leaders, local non-profit organizations interested in ‘green cities' arborists, landscape architects, nursery growers, HOAs, and concerned citizens to register for our free ‘Trees for Tomorrow Start Today' workshop (via Zoom) on Tuesday, March 9, 2021 (8:15am – 3pm).
Please reach out to your city leaders and local ‘green industry' professionals to encourage their attendance and participation. While the workshop is free, registration is required through this secure link: http://ucanr.edu/u.cfm?id=264
A bevy of speakers including certified arborists, horticulturists, planners, water district personnel and other non-profit and green industry representatives will discuss the benefits of urban trees; recommended practices for their selection and care; how to avoid hazardous trees that damage property and structures; and share success stories resulting from partnerships through cities, non-profit organizations, the green industry, HOAs, and street tree committees.
A highlight of the workshop will be the opportunity for attendees to participate in breakout sessions that cut across professions and interest groups (city planners, community service directors, arborists, landscape architects, landscapers, water district managers, HOA managers, golf course superintendents, nursery growers, UC master gardeners, concerned citizens, etc.) to enact positive change regarding tree selection and care.
Thank you for sharing this opportunity to help ensure a healthy future for our children's children with your city leaders and decision-makers.
In the meantime, here are some tree care tips to ‘start the conversation' between now and the workshop:
• Select trees that perform well in your climate. The Sunset Western Climate Zone maps are more precise than USDA zones for our warmer climates. Trees should also be selected based on their adaptation to the ‘micro-climate' in each particular landscape, as well (shade, proximity to buildings, space needs below as well as above ground, soil type, water source, etc.)
• Plant trees the same depth they were in their container in holes at least 2-1/2 times wider. Do not add compost or organic matter to the hole. This practice can result in circled roots that never grow laterally out of the confines of the dug hole.
• Remove any tree ties that are cutting into the trunk or branches of your trees. If trees must be staked due to windy conditions, make sure that the ties are loose enough to allow trees to gently flex in the wind. This helps trees develop the necessary lower trunk strength and stability to support the tree as it matures. Over time, you may be able to completely remove the ties and stakes once the lower trunk becomes stronger and self-supporting.
• Keep all plants and mulch several inches away from tree trunks.
• Keep tree trunks dry. They should not come into contact with water from sprinklers or hoses.
• Regularly water newly planted trees but water mature trees infrequently and deeply. Watering too often reduces the level of oxygen in the rootzone and can lead to waterlogged soils prone to crown and root rots. During fall, trees require only about 15% of the water they require in the summer.
• Prune trees only as needed and avoid topping them. Invest in the services of a credentialed and knowledgeable professional to correctly care for your valued trees. Find a list of International Society of Arboriculture Certified Arborists in your area here: https://www.treesaregood.org/findanarborist.
- Author: Jeannette Warnert
Many common street trees now growing in the interior of California are unlikely to persist in the warmer climate expected in 2099, according to research published in the July 2018 issue of the journal Urban Forestry & Urban Greening.
“Urban foresters in inland cities of California should begin reconsidering their palettes of common street trees to prepare for warmer conditions expected in 2099 due to climate change,” said the study's co-author, Igor Lacan, UC Cooperative Extension environmental horticulture advisor in the Bay Area.
Common trees in Coastal California cities appear to be better suited to withstand the 2099 climate.
“Our research shows that some trees now lining the streets of cities like Fresno, Stockton and Ukiah are likely to perform poorly in 2099,” Lacan said. “Those cities need to look at the conditions – and trees – now found in El Centro, Barstow and Fresno respectively.”
To reach these conclusions, Lacan and co-author, professor Joe McBride of UC Berkeley, used space-for-time substitution. They compared the most common street tree species in cities representing each of the 16 California climate zones with trees in cities that currently have climates that approximate the expected warmer conditions in the 16 cities 80 years from now.
For example, Eureka can expect a climate like Berkeley's today; Fresno's climate will resemble the climate of El Centro today. (Find the complete list of cities below.) The corresponding cities were determined with climate predictions from Cal-Adapt, which synthesizes California climate change scenarios to reach a consensus view of the magnitude of climatic warming.
“We used the mid-range models,” Lacan said. “It's very reasonable to say the warming predicted by the model we used is already ‘baked in,' regardless of any mitigation efforts. While we should take measures to prevent even greater warming – mostly by reducing the use of fossil fuels – this study aims to help adapt California urban forests to the warming that can be reasonably expected to occur.”
Lacan said he and McBride were surprised to find that coastal cities and their warm equivalents contain most of the same common urban tree species, while the warm equivalents of inland cities seemed to lack most and, in some cases, all of the common trees there today.
“It's really a sharp distinction,” Lacan said. “Perhaps they were lucky, but coastal cities are better positioned for the climate of 2099 than the inland cities.”
Climate zone |
City |
Corresponding city |
1 |
Eureka |
Berkeley |
2 |
Ukiah |
Fresno |
3 |
Berkeley |
Santa Ana |
4 |
King City |
Stockton |
5 |
Santa Maria |
Santa Ana |
6 |
Santa Monica |
King City |
7 |
San Diego |
Santa Ana |
8 |
Santa Ana |
Burbank |
9 |
Burbank |
Fresno |
10 |
Riverside |
Barstow |
11 |
Yuba City |
El Centro |
12 |
Stockton |
Barstow |
13 |
Fresno |
El Centro |
14 |
Barstow |
El Centro |
15 |
El Centro |
Furnace Creek |
16 |
Susanville |
Barstow |
For a copy of the complete research report email Igor Lacan, ilacan@ucanr.edu.
- Posted By: Janet Hartin
- Written by: Janet S. Hartin, Univ. of CA Cooperative Extension, San Bernardino and Los Angeles Counties
Dear Certified Arborists, Landscape Contractors, Irrigation Professionals, and Golf Course Superintendents:
Just a reminder that preregistration for the Dec. 14 Univ. of CA-sponsored
Turf and Landscape Institute (program attached) at Etiwanada Gardens
Conference Center in Rancho Cucamonga ends Dec. 10. The cost is only $75
when three sign up together or $85 for a single registration. Lunch and
bottomless coffee all day are included. After Dec. 10 prices increase
significantly.
You can register online at: http://cesanbernardino.ucdavis.edu if paying
by credit card. Otherwise, if paying by check or gov't purchase order,
please complete the registration form that is attached to the 2-page
flyer.
There are three sessions to choose from: Sustainable
Landscaping, Arboriculture (both taught in English), and a third session
(Fundamentals of Landscape Management) taught in Spanish. All sessions
run from 8:00 AM - 4:00 PM and maximal PCA/QAL/QAC; ISA; IA; and GCSAA
accreditation have been applied for.
All sessions offer objective information taught by Univ.of CA and industry
professionals highly knowledgable in their field such as Dr. Loren Oki,
Dr. Ole Becker, Dr.Don Merhaut, Dr. Jim Bethke, Pat Gross, Janet Hartin,
Don Hodel, Toni Monzon, Ruben Green, Ron Mantranga, Jaime Bayona,and many
more.
You are also invited to attend optional 7-8 AM and 4-5 PM Laws and Regs
sessions. If you attend from 7 AM - 5 PM you can earn 7.00 PCA hours.
Lunch, coffee breaks and a table-top trade show are included in the price
Questions? Contactl me (Janet Hartin, co-chair) at 951.313.2023 or
jshartin@ucdavis.edu. If you'd like to arrange for a table-top booth at
our mini tradeshow for $150 for the day and free conference attendance and
lunch contact Steve at sjporus@unlaccess.com.
Hope to see you December 14th!
Janet Hartin
Environmental Horticulturist
Univ. of CA Cooperative Extension
San Bernardino and Los Angeles Counties
951.313.2023
jshartin@ucdavis.edu