Trees for Life

Planting Urban Forests

National Arbor Day is tomorrow, the fourth Friday in April. Hard on the heels of Earth Day, it may be difficult to keep the fervor going, but let’s talk about trees. Now that (almost) everyone agrees that global warming is a fact and that one of the major causes is the release of carbon into the atmosphere through the burning of fossil fuels, it should be easy to see why having more trees around is a good idea. Just to review: Plants use carbon from the atmosphere as a major building block for their bodies. This is called carbon sequestering and-particularly in the case of long-lived species such as trees-can result in a significant reduction in the overall atmospheric carbon load. The more trees, the more carbon is locked up. We may not personally be able to do much about the loss of rain forests, but we can certainly do something about the number of trees in our landscapes.

In cities in particular, trees can provide other real benefits beside that basic one of carbon banking. Cities are the center of much of the air pollution that is released into the atmosphere. By some estimates, about 80 percent of the U.S. population lives in urban centers, driving cars, mowing lawns, and performing myriad acts that contribute to the problem. Besides the obvious value in removing carbon from the air, trees can capture other air pollutants, too, improving air quality.

Further benefits come from the shade that trees can provide. Ozone is formed by ultraviolet light striking oxygen, and is a good thing when it occurs high above the earth in the stratosphere. When it is produced closer to the ground and combines with other elements of smog, it is an irritant to humans and plants alike. Shading is an obvious way to cut down on ozone production. Cooling things down reduces energy needs as well. Exposed concrete and asphalt streets, parking lots, and sidewalks capture and retain immense amounts of heat. Recent research estimates that the 177 million trees that are growing in cities reduce electrical needs for air conditioning equivalent to the output of seven 100-megawatt power plants. Imagine, if every roof were green and trees lined every street, what the energy savings could be.

In addition to air pollution, cities contribute major amounts of water pollution. Many dangerous chemical pollutants can be captured and remediated by ecological processes that are part of parks and other urban forests. Runoff from roofs, roads, and landscapes can contain animal waste, fuel and oil residues, and herbicides and pesticides. Most of these can be broken down by soil organisms in a healthy ecosystem. Planting trees and other vegetation in parks and greenbelts reduces water pollution and loss due to runoff. Green spaces capture rainwater and direct it back into the ground, where it can replenish aquifers. Pavement does the opposite, rushing the water away to be lost from that location.

The health benefits of reduced air and water pollution are pretty obvious. There are other, more subtle results of green spaces as well. Study after study has proved that just being in a green environment results in increased health. Heart rates drop and blood pressure is measurably improved when people spend time outdoors around plants. Stress is a major factor of city living. A walk in the park is one simple treatment to reduce tension.

Participating in planting or maintaining gardens or trees provides an even greater value. The national average for tree cover in urban areas is 27 percent. There are many organizations-local, regional, and national-that promote tree health and tree planting to increase that percentage. Sacramento has launched a regional program to increase its tree canopy to 35 percent over the next 40 years by planting trees in established neighborhoods as well as ensuring that they are a planned part of new building projects. Los Angeles, with a tree cover currently standing at 18 percent, has initiated the Million Trees project. City departments will be planting trees on public property and individual volunteers, community groups, organizations, and businesses will also be pitching in. The Santa Barbara Tree Diversity project, which also encompasses Goleta, has the goal of planting and maintaining 1,000 trees over the next five years, not only enhancing the urban forest, but increasing the diversity of species as well.

Here are some other agencies that are committed to preserving and expanding urban forests. The California Urban Forests Council ( aims to “promote the proper planning, planting, and management of urban and community forests to maximize the quality of life for every Californian.” The Center for Urban Forest Research ( maintains that trees “add value to communities, converting results into financial terms to stimulate more investment in trees.” California Community Forests Foundation ( “partners with organizations, schools, and communities to promote the well-being of urban forests and natural ecosystems through youth and adult environmental education and community-based conservation projects.” Goleta Valley Beautiful ( “has been planting over 500 trees each year for the past several years.” California ReLeaf (, in partnership with the California Department of Forestry (, serves to “empower grassroots efforts and build strategic partnerships that preserve, protect, and enhance California’s urban and community forests.” But urban areas are not the only places where tree preservation is needed. Rural communities also face loss of native trees. The California Oak Foundation ( is “committed to preserving the state’s oak forest ecosystem and its rural landscapes” as well.

Your support of any of these agencies will ensure that future generations of urban dwellers live healthy, happy lives. Celebrate Arbor Day tomorrow-or any day-and plant a tree for your health and that of the planet


Episode 6 of the Garden Wise Guys is on the air. Subtitled “27½ Minutes,” this episode is a spoof of 60 Minutes, and hosts Billy Goodnick and Owen Dell discuss great sustainable gardening techniques. View the show on County TV Channel 20, Monday-Wednesday nights at 10:00 p.m. and City TV Channel 18, Sunday nights at 9 p.m.


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