Strong branches: How trees benefit our everyday lives
Trees are a beautiful part of San Diego’s landscape wherever they are found – on urban streets downtown, lining boulevards, and peppered throughout canyons, open spaces, and on mountainsides that crisscross the county. Trees can also have direct monetary benefits: strategically placing trees around suburban homes can reduce the air conditioning needs of said homes by up to 35%. Trees offer us so many benefits across all areas of our lives, it is easy to overlook some of them. Considerate planting of trees is an ideal way to reduce greenhouse gas (GHG) emissions and reap the many benefits that they can provide. The County Climate Action Plan (CAP) includes measures A-2.1 and A-2.2, both of which encourage additional tree planting on private and county-owned property. This article highlights just a few of the benefits of trees.
Trees are Cool
Trees soak up the sun and, in the process cool areas around them through a few mechanisms. By shading the area below and around the tree, temperatures can be 20-45°F lower than areas in direct sunlight. Trees also cool through evapotranspiration, further reducing temperatures. These qualities can reduce urban heat-island effects in areas with a lot of concrete, asphalt, and other impermeable surfaces.
Trees Filter the Air We Breath
It is not only through temperature that trees can affect the atmosphere, because they also consume carbon dioxide, and reduce levels of different types of air pollution around them too. Most trees lower levels of serious air pollutants, including nitrogen oxides. Trees can also reduce the level of particulate matter (PM) in the air, because their branches and leaves provide a large surface area for PM to deposit and keep as ‘dust’ until a rain comes and washes it off.
Trees Conserve Water and Reduce Erosion
Similarly, trees soak up water during rain events which reduces run-off headed towards the ocean. During storms and rain events, trees absorb or slow down water hitting their leaves, and if there are fallen leaves on the ground, that environment slows down water flow further. Absorption of water reduces erosion and gives it more time to soak into the ground instead of draining into the stormwater system. Evapotranspiration comes into effect again, as all the water absorbed during rains is released back into the atmosphere on sunny days, regulating the temperature around the tree.
Trees Offer Wildlife Watching Opportunities
Trees create habitat for wildlife by providing shelter and sources of food for local wildlife. Trees can provide valuable shelter and sources of food for birds and small animals. A source of shelter is particularly important for birds if there are few trees and shrubs around (such as a grassy lawn).
Trees Improve our Health and Social Well-being
Finally, trees provide invaluable but tangible social and health benefits to people nearby. Living near green spaces and trees can lower blood pressure and improve emotional and psychological health. Trees can create more pleasant experiences for people participating in activities near them and add beauty to a neighborhood. This in turn can lead to positive associations, pride in ownership over homes, parks, businesses, and other public spaces which contributes to increased security. Trees also raise property values, as they are often desirable parts of landscaping around homes.
Trees are incredible parts of our ecosystems that have benefits which go far beyond numbers. County CAP measure A-2.1 requires trees to be planted for every new dwelling unit constructed in the county. Careful selection of trees for the Southern California climate can reap future benefits and hedge against potential costs (drought resistance, fire resistance) which far outweigh the initial cost of planting new trees.