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Why Urban Trees Solve So Many of Our Problems

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*This article originally appeared in Sierra Magazine on September 22, 2015. "SoCalConnected" has received permission to republish the following from SierraClub.org

Trees cover an estimated 20.9 million acres of urban land in the continental United States. That’s 3,659 square feet of urban forest per city dweller—about the size of a not-so-modest four-bedroom house. 

But like housing, trees are not equally distributed across American cities. Studies have shown that there is a higher demand for trees in wealthy neighborhoods. Conversely, areas with a higher proportion of African Americans, low-income residents, and renters enjoy less tree cover.

The unequal allocation of city greenery means that many low-income and non-white urbanites are missing out on the benefits of having trees on their city blocks, which, it turns out, are significant.

If your street is peppered with Magnolias and American Sweet Gums, your neighborhood will look better, sound better, and be less windy. Trees in urban spaces suppress noise, beautify monochromatic pavement, and reduce wind speeds.

If offensive city noises do traverse the leafy canopy outside your window, you’ll be less stressed about it.

In 1984, healthcare design researcher Roger Ulrich conducted a study that revealed post-operative patients with tree views have shorter hospital stays than their counterparts with brick wall views, which Ulrich believed was due in part to reduced stress. Since then, numerous studies have linked verdant surroundings to lower stress levels.

Green spaces will also help bring your community together; they provide opportunities for hands-on environmental education and foster outdoor recreation. Even your grumpy next-door neighbor loves them.

According to a 2010 study by the USDA Forest Service, more foliage also means fewer felonies. Because urban greenery indicates that a neighborhood is well maintained, potential criminals believe they are more likely to be caught and are therefore less likely to risk committing a crime, suggested researchers.

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And, of course, urban trees are awesome for the environment. Every year, city vegetation removes nearly 784,000 tons of air pollution and reduces atmospheric carbon dioxide by about 100 to 200 pounds per tree.

Shady canopies help reduce urban temperatures, which are often hotter than neighboring rural areas. Cooler days temper AC usage, so trees help you save on utilities and reduce your carbon emissions.

Water and soil quality will also benefit from a few Acacias on your block. Trees filter out some of the harmful substances that wash off of roads, parking lots, and roofs during storms, while also reducing surface run-off and flooding risks.

They help out animals and birds, too, by providing sanctuary from the dangers of city living. A 2010 studypointed to the importance of maintaining urban forests as refuges for migrating birds looking for food and rest.

If you aren’t sold on the environmental advantages, city trees are also good for your health. Tree cover mitigates ultraviolet radiation, which can cause harmful skin damage with direct sunlight. City flora has also been associated with lower asthma rates in young children and fewer instances of cardio-metabolic conditions.

Unfortunately, the racially and economically skewed distribution of urban forests in the United States means that not everyone has access to the health benefits that trees provide. This is especially problematic because pollution disproportionately affects minorities and poor Americans.

So, urban forests can basically fix a lot of our problems, but only if everyone has equal access to the social, economic, and health advantages of a little extra tree cover.

WHAT YOU CAN DO

 

This story is a part of a special report exploring tree canopies in Southern California. Learn more at kcet.org/treecanopies

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