Urban forest
Aside from the beautification of the urban environment, they offer many benefits like impacting climate and the economy while providing shelter to wildlife and recreational area for city dwellers.
[2][3] Some sources claim that the largest man-made urban forest in the world is located in Johannesburg in South Africa.
[7] Rio de Janeiro is also home to two of the vastest urban forests in the world, one of which is considered by some sources to be the largest one.
It began as a restoration policy in 1844 to conserve the natural remnants of forest and replant in areas previously cleared for sugar and coffee.
[12][8] The larger metropolitan area encircles the forests which moderate the humid climate and provide sources of recreation for urban dwellers.
Along with seven other smaller full protection conservation units in the city, they form an extensive natural area that contains the Transcarioca Trail, a 180-km footpath.
[14] Several cities within the United States have also taken initiative investing in their urban forests to improve the well-being and economies of their communities.
They are critical in cooling the urban heat island effect, thus potentially reducing the number of unhealthful ozone days that plague major cities in peak summer months.
Ground-level ozone, or smog, is created by chemical reactions between NOx and volatile organic compounds (VOCs) in the presence of sunlight.
Most particulate pollution begins as smoke or diesel soot and can cause serious health risk to people with heart and lung diseases and irritation to healthy citizens.
Unshaded parking lots can be viewed as miniature heat islands, where temperatures can be even higher than surrounding areas.
Ideally, trees should be selected that take in higher quantities of polluting gases and are resistant to the negative effects they can cause.
These particles temporarily rest on the surface of the tree, as they can be washed off by rainwater, blown off by high winds, or fall to the ground with a dropped leaf.
They reduce storm water runoff and mitigate flood damage, protecting the surrounding rivers and lakes.
Birds and small mammals use trees as nesting sites, and reptiles use the shade they provide to keep cool in the hot summer months.
[citation needed] Urban forests contribute to the reduction of energy usage and CO2 emissions primarily through the indirect effects of an efficient forestry implementation.
[26] Computer models indicate that annual energy consumption can be reduced by 30 billion kWh using 100 million trees in U.S. urban areas.
Additionally, the reduction of energy demand would reduce power plant CO2 emissions by 9 million tons per year.
[25] One example of this can be seen in a study carried out over 40 years in Tucson, AZ, which analyzed the savings of stormwater management costs.
[25] In another instance, New York City leaders in the late 1990s chose to pursue a natural landscape management instead of an expensive water treatment system to clean the Catskill/Delaware watershed.
An empirical study from Finland showed a 4.9% increase in property valuation when located just one kilometer closer to a forest.
[30] The reduction of air, light, and noise pollution provided by forests is cause for the notable pricing differentials.
As an experimental mental health intervention in the city of Philadelphia, trash was removed from vacant lots, some of them being selectively "greened" by plantings trees, grass, and installing small fences.
