California Trees Winter 2012


The State of California’s Urban Forests: Integrated Approaches Offer the Best Solutions

By Suzanne Hurt
California’s urban forests are facing a swarm of challenges brought on by climate change and the global recession. As competition for limited local funding increases, the state’s urban forests are falling into a state of dilapidation, suffering from a lack of understanding about the benefits thriving trees provide. According to experts, trees need all the help they can get right now.


“A few years of neglect can be very harmful to an urban forest and its health,” said Greg McPherson, research forester with the Pacific Southwest Research Stationof the U.S. Forest Service in Davis. “Even though trees look like they’re permanent and never changing, they are actually very fragile.”

Fresno Street TreesFresno street trees taken by Matter Ritter

Urban forests are contending with a range of issues including a lack of funding, low priority as a part of communities’ infrastructures, and decreased functionality due to increased stresses. Some problems stem from the current era, dominated by global warming, an enduring recession and a state plagued by a continuing financial crisis. Other problems are more longstanding – tied to under-appreciation of trees for more than just their beauty.


Tree cover in the country’s urban areas is decreasing by 4-million trees a year, according to a U.S. Forest Service study published in “Urban Forestry & Urban Greening.” No research has been done on tree loss throughout California, but the study reported a one-percent decline in trees and shrubs in Los Angeles despite the success of the city’s Million Trees LA campaign.


Trees Work Hard for Communities

Two of the most critical issues confronting the state’s urban forests are people’s limited understanding of the benefits trees provide and the resulting low prioritization urban forests receive. Most people can name basic benefits of the trees in their community, but they don’t realize how much a city or town gains by having a healthy urban forest.


The urban forests’ commonly unacknowledged benefits include:

  • The ability to collect, drain,store, and clean stormwater in their root zones – providing cities with flood protection. These forests help return much-needed water to the watershed.
  • Reduction of air pollution and the offset of global warming by absorbing greenhouse gases and releasing oxygen into the air.
  • Protection from extreme heat and decreased energy costs by shading buildings, streets, and parking lots.
  • Increased property values for homes and higher spending on goods and services provided by businesses on treelined
  • Economic benefits as a $3.6 billion industry that provides more than 60,000 jobs in the state.


According to TreePeople founder Andy Lipkis, only leading urban foresters grasp the full range of services provided by trees, soil and other vegetation, and the way those services could be maximized and integrated into a city’s infrastructure system.


Growing a Forest’s Potential

As a result, many city and county officials give urban forests a low priority as they allocate city and county budgets. In a bad economy when local budgets are tight that translates into two more issues facing the forests: less funding and decreased maintenance.


“For the most part, our urban forests have been created and managed as decorations,” Lipkis says. “In terms of the priorities of a city budget, aesthetics and decoration don’t compete well with public safety and all the other required infrastructure functions, and so they’re not getting the funding.”


A lack of funding for tree planting and maintenance is happening at both the state and local levels. Matt Ritter, an associate botany professor at California Polytechnic State University who wrote “A Californian’s Guide to the Trees Among Us” says finding money for tree care is harder because it’s just not as “sexy.”


Trees need to be watered and maintained, which includes weeding, mulching, proper staking and trimming. Tree maintenance is crucial in a tree’s early years and beyond. Without it many trees are planted and then die. According to Ritter, the average life span of a tree in the L.A. area is seven to ten years.


“Without work and water early on in the tree’s life, the tree has a really high chance of perishing,” Ritter says. “What’s the point of a large planting of trees if they don’t live on to become mature trees?”


Older trees also suffer because cities have cut back on mature tree trimming or even turned street tree maintenance over to property owners. Because many people now entrusted with the care of communities’ trees don’t know how to properly maintain them, cities likely won’t get the full benefit of their urban forests, says State Urban Forester John Melvin.


Additionally, urban trees often need more care than trees in a natural environment, because they grow in harsh surroundings and experience increased stressors. Dr. McPherson says that many city trees don’t grow in enough soil, must endure increased heat and drought from both climate change and intense urban development, and have to battle an increasing number of pests and diseases introduced from other countries.


“Trees have the potential to mitigate heat and drought and protect people from these extreme heat events if they’re healthy and taken care of,” he adds.


Urban trees are also more susceptible to pests and disease, because of the lack of diversity in the urban forest. Parts of the Los Angeles area have about 16 types of trees. In Sacramento’s newer neighborhoods, approximately 20 species make up most of the urban forest, according to Dr. Ritter. Some urban forests are strained from having a lot of old trees, which are less resilient and need more care. Losing them simultaneously to pests or disease would significantly reduce tree canopy and other benefits.


“It’s kind of like having a geriatric urban forest,” Dr. McPherson says.


From Problems to Solutions

While the issues may sound daunting, people who care about trees and the cities they grow in see a mountain of potential solutions.


One solution is to engage communities in tree planting and maintenance, which would help reconnect people with the trees they live among. Andy Lipkis believes that people won’t fight for the trees’ survival unless they feel a connection. Along with planting and maintain trees, communities must also receive education about the benefits of trees, their needs and the value of designing functioning urban forests as a part of forward-thinking, integrated infrastructure management. Education should be targeted to residents, nonprofits, elected officials and government staff, arborists and even many urban foresters.


“Cities need to start becoming aware of the way their urban forests are not performing at their optimum level because of the separation….” Lipkis says. “Nonecosystem-based thinking has become the standard in cities and the law.”


The priority of planting and maintaining urban forests has ebbed and flowed in California, but that can’t happen if the urban forests are to be kept healthy. Lipkis and others recommended residents make urban forests a higher priority and weigh in on how they want public funds spent. As cities struggle to balance budgets, one way to persuade decision-makers may be the use of software that calculates total tree benefits in an individual community.

Trees more than pay for the maintenance they get. A healthy urban forest is the lowest-cost way to offset climate change, Melvin says. “It’s an investment in the future,” he adds. “It’s about whether the urban areas in the state end up being places people want to live, or places people get stuck living in.” 

Urban forests need to be viewed as capital projects that require long-term investment. Most capital projects devalue and degrade after they’re built. Trees become more valuable once planted.


“That’s the last (budgetary item) they should be cutting,” Melvin says. “It’s one of the only infrastructure elements a city has that gains value with time.”


The right response to dried up maintenance funds is not to turn street tree maintenance over to property owners, experts agreed.“Urban forests need to be viewed as a utility the same as any other utility, and you don’t turn maintenance of other utilities over to residents,” Dr. McPherson says.


There are ways a city can care for their urban forest, but still get as much value from their investment as possible. The best ways to do that integrate the forest with other utilities. For example, the Sacramento Municipal Utility District (SMUD) knows that trees can help minimize energy consumption. For the past 22 years, SMUD has partnered with the Sacramento Tree Foundation to provide trees for residents in their service area. These deciduous trees are specifically placed to reduce energy costs by increasing homes’ shade in the summer and allowing the sun’s rays to warm homes in the winter.


Another example benefits communities around California that experience water shortages. Urban forests could be collecting winter rainwater and saving it to water landscaping in the summer. TreePeople, local government and others are working on that concept in the form of an underground cistern as part of a watershed management project in the San Fernando Valley.


A Cost-Effective Urban Forest

Cities can also save money by determining if parts of the urban forest are being overwatered. Communities can conserve water through more efficient management of the land, which could include changing the way it’s landscaped, what tree species are planted, the way land is watered and how much water is applied.


The State Urban Forester advocates for more drought-tolerant landscapes. Trees use less water than the average lawn but provide a lot more benefits. Currently, many California landscapes are watered too much for drought-tolerant trees, which can lead to decay and root disease.


Urban forests would become more resilient, and thus more cost-effective, through increased diversity of native and non-native species. Hundreds of species can grow in California. Nurseries and landscape architects tend to sell and use what’s cheap and what they know works, Dr. Ritter says.


Foresters and residents can easily identify tree species not growing in a neighborhood and plant one. To do that, use the SelecTree guide,, on CalPoly Urban Forest Ecosystem Institute’s website and ask a nursery to order that species.


Dr. Ritter has identified the Silver Linden, Soapbark Tree, Persian Ironwood and Bald Cypress as four undeservedly rare trees for Northern California. The Weeping Myall, Rose Gum, Toog Tree and Leopard Tree are four rare species in Southern California.

For urban forests that are already suffering from pests or diseases, Dr. McPherson and UC Davis graduate student Louren Kotow recently developed the California Municipal Forest Health Threat Assessment. The tool recommends specific ways communities can reduce risks to their unique urban forests, such as not planting trees known to be susceptible to pests and disease.

MLK before picMLK before picBefore and after pictures of Martin Luther King, Jr. Blvd in L.A. – The first was taken just before the trees were planted by TreePeople in 1990. The second, featuring TreePeople founder and Executive Director Andy Lipkis, was taken in 2008. What a difference trees make!

Funding Urban Forests

In addition to maintaining their urban forests, communities should also look for new ways to fund them. While state bond funds for projects have been plentiful for the last 15 years, John Melvin recommends local governments and nonprofits find more creative funding sources now that state grants are drying up.


Some residents have voted to approve additional taxes for landscape maintenance districts in their communities. Local officials can also propose bond measures to help pay for tree maintenance, according to Melvin.


The health of California’s urban forests is not only in the hands of individual communities though. Dr. McPherson and the U.S. Forest Service are working with California ReLeaf, the California Department of Forestry and Fire Protection (CAL FIRE), the California Urban Forests Council, the California Air Resources Board and Climate Action Reserve to develop protocols to sell carbon offsets from tree planting projects to help fund tree planting and care under the provisions of California Assembly Bill 32.


California ReLeaf is also currently exploring other potential sources of revenue to replace disappearing CAL FIRE funds.


Keeping California’s urban forests healthy is a responsibility of every Californian. Residents of communities across the state are suffering from the loss of natural landscapes and the services they provide. Forests, grasslands and other natural ecosystems have been cut down, paved over and filled with buildings. Working together, we can not only redevelop those environments, but also integrate them into our cities and towns in ways that reinforce forest health, community health, and economic health.


“The role of urban forests is so critical because forests did produce these services and they can again,” Andy Lipkis says. Hope still exists in the urban forest.

Suzanne Hurt is a Sacramento journalist whose work can be found via Wild Journalism.