Қалалық орман шаруашылығы және қала ішіндегі ағаштар жиынтығы

Collection of trees within a city, town or a suburb
forests in cities

An urban forest is a forest, or a collection of trees, that grow within a city, town or a suburb. In a wider sense, it may include any kind of woody plant vegetation growing in and around human settlements. As opposed to a forest park, whose ecosystems are also inherited from wilderness leftovers, urban forests often lack amenities like public bathrooms, paved paths, or sometimes clear borders which are distinct features of parks. Care and management of urban forests is called urban forestry. Urban forests can be privately and publicly owned. Some municipal forests may be located outside of the town or city to which they belong. Urban forests play an important role in ecology of human habitats in many ways. 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.

In many countries there is a growing understanding of the importance of the natural ecology in urban forests. There are numerous projects underway aimed at restoration and preservation of ecosystems, ranging from simple elimination of leaf raking and elimination of invasive plants to full blown reintroduction of original species and riparian ecosystems. Some sources claim that the largest man made urban forest in the world is located in Johannesburg in South Africa. The city is located in the highveld, a grassland biome typically lacking large numbers of trees, yet Johannesburg is still a very densely wooded city with reportedly 10 million artificially introduced trees and is rated as the city with the eighth highest tree coverage in the world. 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. Tijuca Forest is the most famous. 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. Despite the worldwide recognition of Tijuca Forest, another forest in the same city encompasses roughly three times the size of its more prominent neighbor: Pedra Branca State Park occupies 12,500 hectares (30,888 acres) of city land, against Tijuca's 3,953 hectares (9,768 acres). Sanjay Gandhi National Park in Mumbai, Maharashtra, India is also an example of an urban forest. It covers roughly around 20% area of the city. The forest is filled with many animals freely roaming around. It also has an important cultural site of ancient history situated in it known as the Kanheri caves. Nebraska National Forest is the largest man made forest in the United States located in the state of Nebraska. It lies in several counties within the state and is a popular destination for campers year round. 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. Some notable cities among them are Austin, Atlanta, New York, Seattle, and Washington, D. C. New York, for example, has taken initiative to combat climate change by planting millions of trees around the city. In Austin, private companies are funding tree planting campaigns for environmental and energy saving purposes.

Urban forests play an important role in benefitting the environmental conditions of their respective cities. They moderate local climate, slowing wind and stormwater, and filter air and sunlight. 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.

Urban forests and trees help purify water sources by slowing down rain as it falls to the earth and help it soak into the soil, thereby naturally filtering out pollutants that can potentially enter water supply sources. They reduce storm water runoff and mitigate flood damage, protecting the surrounding rivers and lakes. Trees also help alleviate the load on "grey" infrastructure (such as sewers and drains) via evapotranspiration. Trees are ideally suited as their canopies can intercept water (and provide dense vegetation), whilst their roots can pump substantial amounts of water back into the atmosphere as water vapor, all with a relatively small footprint.

Trees in urban forests provide food and shelter for wildlife in cities. Birds and small mammals use trees as nesting sites, and reptiles use the shade they provide to keep cool in the hot summer months. Furthermore, trees provide shade necessary for shrubbery. Not only do urban forests protect land animals and plants, they also sustain fish and water animals that need shade and lower temperatures to survive.

The economic benefits of trees and various other plants have been understood for a long time. Recently, more of these benefits are becoming quantified. Quantification of the economic benefits of trees helps justify public and private expenditures to maintain them. One of the most obvious examples of economic utility is the example of the deciduous tree planted on the south and west of a building (in the Northern Hemisphere), or north and east (in the Southern Hemisphere). The shade shelters and cools the building during the summer, but allows the sun to warm it in the winter after the leaves fall. The physical effects of trees—the shade (solar regulation), humidity control, wind control, erosion control, evaporative cooling, sound and visual screening, traffic control, pollution absorption and precipitation—all have economic benefits.

Urban forests contribute to the reduction of energy usage and CO2 emissions primarily through the indirect effects of an efficient forestry implementation. The shade provided by trees reduces the need for heating and cooling throughout the year. As a result, energy conservation is achieved which leads to a reduction of CO2 emissions by power plants. notes on page 17 that "Businesses flourish, people linger and shop longer, apartments and office space rent quicker, tenants stay longer, property values increase, new business and industry is attracted" by trees.

Urban forests have been linked to an increase in property value surrounding residents. An empirical study from Finland showed a 4.9% increase in property valuation when located just one kilometer closer to a forest. Another source claims this increase can range as high as 20%. The reduction of air, light, and noise pollution provided by forests is cause for the notable pricing differentials.

Urban forests offer many benefits to their surrounding communities. Removing pollutants and greenhouse gases from the air is one key reason why cities are adopting the practice. Removing pollutants from the air, urban forests can lower risks of asthma and lung cancer. Communities that rely on well water may also see a positive change in water purity due to filtration. The amenities provided by the city of each urban forest varies. Some amenities include trails and pathways for walking or running, picnic tables, and bathrooms. These healthy spaces provide for the community a place to gather and live a more active lifestyle.

Living near urban forests have shown positive impacts on mental health. 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. Residents near the "greened" lots who had incomes below the poverty line reported a 68% decrease in feelings of depression, while residents with incomes above the poverty line reported a decrease of 41%. The Biophilia hypothesis argues that people are instinctively drawn to nature, while Attention Restoration Theory goes on to demonstrate tangible improvements in medical, academic and other outcomes, from access to nature. Proper planning and community involvement are important for the positive results to be realized.

In addition to providing economic benefits at the community level, trees also benefit individual homeowners. A tree on a home's landscape or around the house can increase the dollar value received for the home upon sale. According to one study, a tree planted in the front yard can increase a home's sale price by $7,130 and raise the sale prices of surrounding homes. Healthy urban forests also correlate with higher incomes. In communities that have thriving urban forests, there are higher incomes, higher numbers of jobs associated with those communities, and higher productivity of workers.