Nashville is home to some spectacular urban forests as well, the largest being the Warner Parks just south of the city. These parks include over 3,000 acres of woodlands, including old growth forest, and 16.75 miles of hiking trails.
Central Park, as well as Percy and Edwin Warner Parks, are considered urban forests and it’s easy to see why: they contain forests in urban centers. But urban forestry is more than lush parks, dense with trees and foliage. The common definition of urban forests also includes trees along roadsides, greenways, river corridors and riparian areas, and in gardens and other more pedestrian green spaces.
Nashville needs more urban forests. And not just for beauty’s sake. Many people don’t realize the invisible benefits—and there are quite a few—that trees bring to our cities. With more than 80% of U.S. residents living in urban centers, trees are more important than ever.
The Disappearance of Green Things
When cities grow, natural green spaces are often replaced by the dull black and gray tones of asphalt, concrete, and steel. Sounds depressing, right? Well that’s because it actually is.
A lack of greenery can lead to increased depression. A recent study found a correlation between green spaces and mental health and concluded that green spaces (trees, shrubs, grasses) in dense urban areas significantly reduce “feelings of depression and worthlessness” in those living nearby.1
Have you ever walked barefoot on asphalt on a hot, sunny day? The sun’s rays bake the asphalt, which stores this heat and makes the surface nearly as hot as coals on a campfire. With the asphalt and other hard surfaces in our cities acting like heaters, the surrounding air temperature also heats up, creating what is known as the urban heat island effect(UHI).
The best way to reduce the heat island effect and keep our cities from overheating is to prevent paved surfaces from absorbing so much heat. And what’s the best way to add shade to cool these paved surfaces? Planting trees!
Cool it down
A side benefit to reducing the environment temperature in dense urban areas is the effect it has on energy costs. Shaded pavement and buildings means that there is less need for city residents to use their air conditioners as often. This reduces the draw on the electrical grid and lowers energy costs.
When rain falls onto our hard surfaces like roads and rooftops, it collects into tiny rivulets and speeds quickly in whatever direction is the fastest way downhill (e.g. gully, storm drain, a road). With enough rainfall, those rivulets combine to become full-fledge streams and they can dump large volumes of water into nearby creeks and rivers.
In flooding situations a few minutes can be the difference between a high stream to violent torrents of water capable of sweeping away automobiles. We are all too aware of the problems flooding can cause in Nashville.
Anything that can slow the water down—grassy areas, trees, shrubs—greatly reduces flooding risk. In contrast to hard surfaces, when rain falls on the ground, soil acts like a sponge, absorbing the water until the sponge is full. Trees access the water via their root system in a manner similar to sipping a soda through a straw.
If you think the amount of water trees can store is marginal, think again. A large tree can take in 100 gallons of water in a single day. That’s no small task.
Dense urban areas are more likely to have problems with air pollution, which can include byproducts from industrial factories, heavy metals, and dust. Trees help absorb these pollutants, improving air quality and respiratory health by reducing the triggers that cause asthma attacks. A study in the U.K. found that adding 300 trees to a square kilometer area reduced the number of asthma-related trips to the emergency room to 50 per 100,000 the study’s 15-year period.
According to the U.S. Forest Service, trees save an average of eight lives per year in New York City.
These are only a few of the human health and environmental benefits of an increased urban canopy. And any one of these benefits is reason enough to expand urban greenspaces. No one wants flooding, overheating, or high energy bills. No one wants to breathe toxic air or suffer from depression.
But the oft-overlooked reason for creating more urban forests in our city is simply because we humans love trees. We scale their heights as children, and play in their shade. Backyard trees become old friends, and we plant trees to honor loved ones. And on top of all these reasons why urban forests are important? Trees are beautiful.
And that is reason enough.