Tuesday, May 27, 2014

Forests & Cities: Urban Forests

From the American Forests.org website. 
Also, some of why I do what I do! 
The Challenge
  • Because of their proximity to human activity, urban forests are exposed to more man-made disturbances than their rural counterparts, which can negatively affect their health, growth and ability to perform ecosystem services.
  • Many non-native invasive species and diseases are introduced in urban areas, threatening the urban forest and potentially spreading to rural forests.
  • Urban areas are subject to much higher rates of pollution than rural areas, threatening the health of both people and urban forests.
  • As urban areas continue to expand, forests become fragmented and destroyed, decimating forest health and biodiversity.
  • Urban areas have lost more than 600 million trees to development over the last 30 years, and urban areas are expected to increase substantially over the next 50 years.
Why We Care
American Forests defines urban forests as “ecosystems composed of trees and other vegetation that provide cities and municipalities with environmental, economic and social benefits. They include street and yard trees, vegetation within parks and along public right of ways, water systems, fish and wildlife.” Thus, urban forests are not only just about the trees in the city, but rather they are a critical part of the green infrastructure that makes up the city ecosystem.
All trees provide certain benefits to their ecosystems. In an urban forest, many of those benefits are directly related to the people who live around them. Since more than 80 percent of Americans live in urban areas, it is important to understand the many ecosystems services that our urban forests provide.
Urban forest help purify the air we breathe. Just 100 trees can remove two tons of carbon dioxide from the air annually. Urban trees in the lower U.S. have been found to remove nearly 800,000 tons of air pollution from the atmosphere every year. In the modern day of bustling factories and countless cars on the road, this service of air purification has become more necessary than ever.
The third grade class at Comstock Elementary helps plant flowers and shrubs on campus
Urban forests help manage a city’s water. Because a city has so many impermeable surfaces, rainwater often builds up rather than being absorbed into the ground. This means that even a small rainstorm can cause flooding, as most of the water overflows into the stormwater system rather than into the ground. As the rainwater flows over the pavement, it becomes contaminated with pollutants and may eventually end up in our urban streams and waterways — and even our faucets. Urban forests help in several ways: They intercept rainfall, allowing the water to be absorbed into the tree, roots and soil. This often results in cities not having to build as many artificial stormwater controls, saving the city and its citizens money. Urban forests purify the water on its way into the ground by removing the pollutants collected. The water retained by the urban forest also helps to sustain the growth of the urban trees, parks and vegetation. These services, provided naturally instead of artificially, can save a city billions of dollars each year. In fact, a single front-yard tree can intercept 760 gallons of rainwater in its crown, reducing runoff and flooding on your property.[1]
Urban forests also help reduce energy demand. When planted in the right place, urban forests provide shade to homes, businesses, roads and parking lots. Anyone who has parked under a tree on a hot day can appreciate the cooling effects of foliage, but did you know that it could also improve your health and save you money? In parking lots, trees help keep the cars cool — 40-50 degrees cooler, in fact— and cooler cars produce less pollution. Shade around your home can do the same thing. Just three large trees around your home, two on the west side and one on the east, can provide enough shade to reduce your air-conditioning costs by 30 percent in the summer. And, when placed properly to reduce wind exposure, they can reduce heating bills in the winter by two to eight percent. In fact, 100 million mature trees growing around homes in the U.S. can save a collective $2 billion every year in energy costs.
These are only a few of the many benefits that urban forests can provide if kept healthy and cared for properly. They also provide bird and wildlife habitat and recreational opportunities, improve soil quality, reduce stress and crime rates, create a natural buffer to reduce the everyday noise of the city, add to your home’s property value and more.