|Part of Washington, DC's urban forest as viewed from the National Cathedral|
To understand why the urban forest is important, it's critical to understand the concept of Ecosystem Services. Ecosystem services are benefits that humans receive from the surrounding environment. These benefits can be categorized into four types of services: supporting (such as formation of soil), regulating (filtering of water and air), provisioning (food or timber), and cultural (such as recreation). Trees are powerhouses of ecosystem services, improving our quality of life every day through functional processes.
Trees pull carbon from the air and produce oxygen, improving local air quality and reducing carbon in the global atmosphere.
Trees reduce the impact of rainfall in a community by actively absorbing water and by slowing runoff as it clings to the surface area of each leaf, stem, branch and trunk.
|Rainwater clings to the leaves, branches, stems and bark of trees, slowing demand on infrastructure.|
Trees improve the quality of our drinking water by filtering pollutants and material, reducing the need for pre-treatment of municipal supplies.
Trees reduce heating and cooling costs by shading homes in summer and blocking wind in winter.
Trees reduce heat island effect, a phenomenon which can raise local temperatures when the summer sun heats concrete and asphalt.
Trees increase property values: the American dream is lined with leafy, sun-dappled neighborhoods.
|Tree plantings are an integral part of the streetscape in downtown Shirlington, Virginia|
|A grove of established trees in a neighborhood park in Rock Island, Illinois|
Trees promote biodiversity: birds, mammals, insects, fungi and microbes form a distinct web that increases quality of life for humans, from harvesting aspirin from willow bark to housing birds and bats that eat mosquitoes.
Trees provide food security by offering habitat to pollinators of crops.
Trees feed us: the harvesting of edible fruits, nuts and berries for consumption is called permaculture.
'Trees are the answer' is a phrase borrowed from a professor to indicate the myriad ways that our communities benefit from a healthy urban forest. Trees are the single biggest investment cities can make in themselves. But it has to be a real commitment to investment, willing to provide the space and resources trees need to thrive and produce reliable benefits we can enjoy.
Future posts will point out challenges to maintaining a healthy urban forest by discussing the limitations of trees. Limitations include failing to thrive under stress or resource deprivation, and being unable to break up with us when we treat them poorly or move when they don't like their neighbors.
|Summertime at the National Arboretum in Washington, DC|