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. In a narrower sense (also called forest park) it describes areas whose ecosystems are inherited from wilderness leftovers or remnants. Care and management of urban forests is called urban forestry. Urban forests may be publicly owned municipal forests, but the latter may also 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: they filter air, water, sunlight, provide shelter to animals and recreational area for people. They moderate local climate, slowing wind and stormwater, and shading homes and businesses to conserve energy.  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.
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.But others claim that this could be a myth. Tijuca Forest, in Rio de Janeiro, has also been considered to be the largest one.
The benefits of urban trees and shrubs are many, including beautification, reduction of the urban heat island effect, reduction of stormwater runoff, reduction of air pollution, reduction of energy costs through increased shade over buildings, enhancement of property values, improved wildlife habitat, and mitigation of overall urban environmental impact.
The presence of trees reduces stress, and trees have long been seen to benefit the health of urban dwellers. The shade of trees and other urban green spaces make place for people to meet and socialize and play. 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.
Trees and shrubs provide nesting sites and food for birds and other animals. People appreciate watching, feeding, photographing, and painting urban wildlife and the environment they live in. Urban trees, shrubs and wildlife help people maintain their connection with nature.
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 USDA Guide 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. 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.
As cities struggle to comply with air quality standards, trees can help to clean the air. The most serious pollutants in the urban atmosphere are ozone, nitrogen oxides (NOx), sulfuric oxides (SOx) and particulate pollution. Ground-level ozone, or smog, is created by chemical reactions between NOx and volatile organic compounds (VOCs) in the presence of sunlight. High temperatures increase the rate of this reaction. Vehicle emissions (especially diesel), and emissions from industrial facilities are the major sources of NOx. Vehicle emissions, industrial emissions, gasoline vapors, chemical solvents, trees and other plants are the major sources of VOCs. Particulate pollution, or particulate matter (PM10 and PM25), is made up of microscopic solids or liquid droplets that can be inhaled and retained in lung tissue causing serious health problems. 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. Trees are an important, cost-effective solution to reducing pollution and improving air quality.
With an extensive and healthy urban forest air quality can be drastically improved. Trees help to lower air temperatures and the urban heat island effect in urban areas. This reduction of temperature not only lowers energy use, it also improves air quality, as the formation of ozone is dependent on temperature. Trees reduce temperature not only by directly shading: when there is a large number of trees it create a difference in temperatures between the area when they are located and the neighbor area. This creates a difference in atmospheric pressure between the two areas, which creates wind. This phenomenon is called urban breeze cycle if the forest is near the city and park breeze cycle if the forest is in the city. That wind helps to lower temperature in the city.
Temperature reduction from shade trees in parking lots lowers the amount of evaporative emissions from parked cars. Unshaded parking lots can be viewed as miniature heat islands, where temperatures can be even higher than surrounding areas. Tree canopies will reduce air temperatures significantly. Although the bulk of hydrocarbon emissions come from tailpipe exhaust, 16% of hydrocarbon emissions are from evaporative emissions that occur when the fuel delivery systems of parked vehicles are heated. These evaporative emissions and the exhaust emissions of the first few minutes of engine operation are sensitive to local microclimate. If cars are shaded in parking lots, evaporative emissions from fuel and volatilized plastics will be greatly reduced.
The volatile components of asphalt pavement evaporate more slowly in shaded parking lots and streets. The shade not only reduces emissions, but reduces shrinking and cracking so that maintenance intervals can be lengthened. Less maintenance means less hot asphalt (fumes) and less heavy equipment (exhaust). The same principle applies to asphalt-based roofing.
Trees also reduce pollution by actively removing it from the atmosphere. Leaf stomata, the pores on the leaf surface, take in polluting gases which are then absorbed by water inside the leaf. Some species of trees are more susceptible to the uptake of pollution, which can negatively affect plant growth. Ideally, trees should be selected that take in higher quantities of polluting gases and are resistant to the negative effects they can cause.
A study across the Chicago region determined that trees removed approximately 17 tonnes of carbon monoxide (CO), 93 tonnes of sulfur dioxide (SO2), 98 tonnes of nitrogen dioxide (NO2), and 210 tonnes of ozone (O3) in 1991.
Urban forest managers are sometimes interested in the amount of carbon removed from the air and stored in their forest as wood in relation to the amount of carbon dioxide released into the atmosphere while running tree maintenance equipment powered by fossil fuels.
In addition to the uptake of harmful gases, trees act as filters intercepting airborne particles and reducing the amount of harmful particulate matter. The particles are captured by the surface area of the tree and its foliage. 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. Although trees are only a temporary host to particulate matter, if they did not exist, the temporarily housed particulate matter would remain airborne and harmful to humans. Increased tree cover will increase the amount of particulate matter intercepted from the air.
One important thing to consider when assessing the urban forest's effect on air quality is that trees emit some biogenic volatile organic compounds (BVOCs). These are the chemicals (primarily isoprene and monoterpenes) that make up the essential oils, resins, and other organic compounds that plants use to attract pollinators and repel predators. As mentioned above, VOCs react with nitrogen oxides (NOx) to form ozone. BVOCs account for less than 10% of the total amount of BVOCs emitted in urban areas. This means that BVOC emissions from trees can contribute to the formation of ozone. Although their contribution may be small compared with other sources, BVOC emissions could exacerbate a smog problem.
Not all species of trees, however, emit high quantities of BVOCs. The tree species with the highest isoprene emission rates should be planted with caution:
Trees that are well adapted to and thrive in certain environments should not be replaced just because they may be high BVOC emitters. The amount of emissions spent on maintaining a tree that may emit low amounts of BVOCs, but is not well suited to an area, could be considerable and outweigh any possible benefits of low BVOC emission rates.
Trees should not be labeled as polluters because their total benefits on air quality and emissions reduction far outweigh the possible consequences of BVOC emissions on ozone concentrations. Emission of BVOCs increase exponentially with temperature. Therefore, higher emissions will occur at higher temperatures. In desert climates, locally native trees adapted to drought conditions emit significantly less BVOCs than plants native to wet regions. As discussed above, the formation of ozone is also temperature dependent. Thus, the best way to slow the production of ozone and emission of BVOCs is to reduce urban temperatures and the effect of the urban heat island. As suggested earlier, the most effective way to lower temperatures is with an increased canopy cover.
These effects of the urban forest on ozone production have only recently been discovered by the scientific community, so extensive and conclusive research has not yet been conducted. There have been some studies quantifying the effect of BVOC emissions on the formation of ozone, but none have conclusively measured the effect of the urban forest. Important questions remain unanswered. For instance, it is unknown if there are enough chemical reactions between BVOC emissions and NOx to produce harmful amounts of ozone in urban environments. It is therefore, important for cities to be aware that this research is still continuing and conclusions should not be drawn before proper evidence has been collected. New research may resolve these issues.
Altona North is a suburb of Melbourne, Victoria, Australia, 10 km south-west of Melbourne's Central Business District, located within the City of Hobsons Bay local government area. Altona North recorded a population of 12,152 at the 2016 census. Bordering suburbs include Altona, Brooklyn, Laverton North, Newport, South Kingsville, Williamstown North, Yarraville. In addition to Paisley Park sporting complex, Altona North is home to three parks, S J Clement Reserve - Gilligan Rd, W L J Crofts Reserve - Blackshaws Rd, Urban Forest Reserve - Grieve Pde.Arroceros Forest Park
The Arroceros Forest Park is a riverside park in Manila, Philippines, located on Antonio Villegas Street (former Calle Arroceros) in the central district of Ermita. Developed in 1993, the 2.2-hectare (5.4-acre) urban forest on the south bank of the Pasig River, at the foot of Quezon Bridge, consists of secondary growth forest with 61 different tree varieties and 8,000 ornamental plants providing a habitat for 10 different bird species. Despite its small size, it is considered an important feature of the city. It lies in a historic area of Manila and has been called "Manila's last lung", being the city's only nature park. The park is administered by the City Government of Manila in partnership with private environmental group, Winner Foundation.Bulldozer Exhibition
The Bulldozer Exhibition (Russian: Бульдо́зерная вы́ставка) was an unofficial art exhibition on a vacant lot in the Belyayevo urban forest by Moscow and Leningrad avant-garde artists on September 15, 1974. The exhibition was forcefully broken-up by a large police force that included bulldozers and water cannons, hence the name.
Since the 1930s in the Soviet Union Socialist realism had been the one of the artstyles largely supported by the state. All other forms of art were forced underground and sometimes prosecuted. One of the attempts to break out of the underground to more public view was the Belyayevo exhibition.
It was organised by three underground artists, Oscar Rabin (artist), Youri Jarkikh (Jarki) and Alexander Gleser. Among the artists taking part in the exhibition were Evgeny Rukhin, Valentin Vorobyov (b. 1938), Vladimir Nemukhin, Lidiya Masterkova, Borukh Steinberg, Nadegda Elskaja, Alexander Rabin, Vasilij Sitnikov, Vitaly Komar and Alexander Melamid. It was held on a vacant lot, officially part of an urban forest (лесопарк) in Belyayevo. Attendance consisted of approximately twenty artists and a group of spectators that included relatives, friends of the artists, friends of the friends and some Western journalists. The paintings were installed on makeshift stands made out of dump wood.
The organizer Oscar Rabin told in an interview in London in 2010: "The exhibition was prepared as a political act against the oppressive regime, rather than an artistic event. I knew that we'd be in trouble, that we could be arrested, beaten. There could be public trials. The last two days before the event were very scary, we were anxious about our fate. Knowing that virtually anything can happen to you is frightening." Rabin was arrested and punished with expulsion from Russia, but was allowed to leave with his family to Paris.Despite the minor size of the event it was considered by the authorities as very serious. They marshalled a large group of attackers that included three bulldozers, water cannons, dump trucks and hundreds of off-duty policemen. Officially, the group was supposed to be "gardeners" expanding the urban forest, who reacted in spontaneous outrage to the offense against their proletarian sensibilities. It was never denied, though, that they got their orders from the KGB.
The attackers destroyed the paintings, beat and arrested the artists, spectators and journalists. One of the most dramatic scenes was Oscar Rabin who went through the exhibition hanging to the blade of the bulldozer. One of the attackers, militsia lieutenant Avdeenko, memorably shouted at the artists: "You should be shot! Only you are not worth the ammunition ..." ("Стрелять вас надо! Только патронов жалко...").
Rabin later recounted the horror of seeing art crushed and artists arrested: "It was very frightening … The bulldozer was a symbol of an authoritarian regime just like the Soviet tanks in Prague." Two of his own paintings - a landscape and a still life - were among those flattened by bulldozers or burned by the invading KGB.After the event was widely publicized in the Western media, embarrassed authorities were forced to allow a similar open air exhibition in the Izmailovo urban forest two weeks later on 29 September 1974. The new exhibition of works of 40 artists was held for four hours and was visited by thousands of people (the numbers cited differ from one and a half thousand  to twenty-five thousand ). A participant in the exhibitions, Boris Zhutkov, has said that the quality of the Izmaylovo paintings was much lower than the paintings in Belyayevo, since in the original exhibition the artists showed the best paintings they had only to have most of them destroyed. The four hours in the forest of the Izmailovo exhibition has often been remembered as "The Half-day of Freedom." The Izmailovo exhibition in turn gave way to other exhibitions of nonconformist art which were very important in the history of modern Russian art.Friends of the Urban Forest
Friends of the Urban Forest (FUF) is a non-profit organization based in San Francisco that plants and maintains trees within the city of San Francisco and its surroundings.
FUF was organized as a response to San Francisco's lack of trees. The group's first tree planted was a glossy privet on arbor day, 1981, in Noe Valley. As of 2006, the organization had planted approx. 40,000 trees.I-Tree
i-Tree is a collection of urban and rural forestry analysis and benefits assessment tools. It was designed and developed by the United States Forest Service to quantify and value ecosystem services provided by trees including pollution removal, carbon sequestration, avoided carbon emissions, avoided stormwater runoff, and more. i-Tree provides baseline data so that the growth of trees can be followed over time, and is used for planning purposes. Different tools within the i-Tree Suite use different types of inputs and provide different kinds of reports; some tools use a 'bottom up' approach based on tree inventories on the ground, while other tools use a 'top down' approach based on remote sensing data. i-Tree is peer-reviewed and has a process of ongoing collaboration to improve it.
There are seven different i-Tree applications which can enhance an individual's or organization's understanding of the benefits which trees provide in modern society. Over the course of many years the U.S. Forest Service has developed and refined these different applications: i-Tree Eco, i-Tree Landscape, i-Tree Hydro, i-Tree Design, i-Tree Canopy, i-Tree Species, i-Tree MyTree, i-Tree Streets, and i-Tree Vue.Izmaylovsky Park
Izmaylovsky Park or Izmaylovo Park is one of the largest parks in Moscow, Russia. The park consists of two areas: Izmaylovsky forest and Izmaylovsky Park for recreation. It is situated in the Izmaylovo District in the northeast of the city. The northern border of the park is the tram line alongside the Izmailovskaya station of the Moscow Metro that serves the park, the southern is the Entuziastov Highway. To the east the park is limited by the main alley and to the west by Electrodny proezd and 1st and 2nd streets of the Izmaylovo menagerie.Jefferson Memorial Forest
The Jefferson Memorial Forest is a forest located in southwest Louisville, Kentucky, in the Knobs region of Kentucky. At 6,500 acres (26 km2), it is the largest municipal urban forest in the United States.The forest was established as a tribute to Kentucky's veterans, and was designated as a National Audubon Society wildlife refuge.Metsälä
Metsälä (Swedish: Krämertsskog) is a subdivision of Helsinki with about 1,000 inhabitants. It has predominantly small houses and it is situated between Maunula and Käpylä. Administratively speaking, Metsälä is a part of the Maunula district. The distance to Helsinki City Centre is about 6 kilometres from Metsälä. The primary housing type has been wooden single-family homes, and a lot of terraced houses have been in the area in the 1970s. Nowadays Metsälä has few unbuilt lots.
Metsälä can be separated into two functionally different parts. In the north, there is a residential area dominated by small houses. On the west side of this area, there is an urban forest belonging to the Maunulanpuisto park in the Helsinki Central Park. In the east, Metsälä is bordered by Tuusulanväylä. On the other side of the highway, there is Patola, or the old part of Oulunkylä.
Traffic connections to Metsälä are excellent. It can easily be reached by bicycle, mass transit or car. In the southeast part of the area, there is Käpylä railway station belonging to the Helsinki commuter rail system. Using walkways, Metsälä can be reached easily from the west through Central Park and from the east along the railway and through the station area.
Metsälä used to be a busy logistics centre, especially south of Asesepäntie and north of the Pasila railway yard. Transportation and freight traffic companies in this area used to provide the majority of 1,020 jobs in Metsälä (as of December 31, 2003). As of 2018, DB Schenker's old building is the only one left, as residential buildings are being built and distribution centres moved closer to the Vantaa airport or other Uusimaa locations.Morningside Nature Preserve
The Morningside Nature Preserve is a project initiated by the Wildwood Urban Forest Committee to stop the destruction of 30 acres (120,000 m2) of forest located in northeast Atlanta and to develop this land for leisure and educational uses, but in a way that is consistent with conservation principles, including protection of water resources and native vegetation.San Juan Botanical Garden
The San Juan Botanical Garden, also known as the Botanical Garden of the University of Puerto Rico, is located in the Caribbean city of San Juan, capital of Puerto Rico. This lush 300-acre (1.2 km2) “urban garden” of native and exotic flora serves as a laboratory for the study, conservation and enrichment of plants, trees, flowers, grasses and many other plants. Seventy-five acres are landscaped and open to the general public as well as researchers.
The entrance is located off the south side of the intersection of Highway 1 and Road 847 in Río Piedras. The “Bosque Urbano del Nuevo Milenio” or (Urban Forest of the New Millennium), a project for the conservation and growth of the urban forest, is on the eastern side of the Botanical Garden.Tanyard Creek Park
Tanyard Creek Park is a 14.5-acre (5.9 ha) park in the Buckhead area of Atlanta. It is located along Tanyard Creek between Collier Road on the north and BeltLine rail corridor to the south. The neighborhood of Collier Hills borders it on the west and Collier Hills North on the east.
A 1-mile (1.6 km)-long BeltLine trail runs through the park - not along the BeltLine rail corridor itself but perpendicular to it. The trail begins at the west end of Colonial Homes neighborhood, proceeds west along the south end of Bobby Jones Golf Course, Louise G. Howard Park, under Collier Road and through Tanyard Creek Park, under a trestle bridge (active CSX rail line), connecting to both Ardmore Park in the Ardmore neighborhood and into the Tanyard Creek Urban Forest. The trail, and urban forest, terminates at Semel Circle, a new infill development area at the back of Brookwood neighborhood. The trail opened in April 2010.The Civil War Battle of Peachtree Creek took place in and around the park.Thomas van der Hammen Natural Reserve
The Thomas van der Hammen Natural Reserve or Thomas van der Hammen Forest Reserve is an area of the Bogotá savanna that is under environmental protection. The natural reserve was declared as such in year 2000 by the Ministry of Environment and Sustainable development. It takes its name from the Dutch-Colombian geologist Thomas van der Hammen who devoted his life to the research of the region. The surface area of the protected reserve is approximately 1,395 hectares (3,450 acres) and it is located in the north of Bogotá.
The protection area has the purpose of creating an urban forest that connects the Bogotá River and the Eastern Hills of Bogotá, to preserve the underground water sources, improve the quality of the air and protect the diversity and activities of the animal species that exist there.Mayor of Bogotá Enrique Peñalosa has proposed construction in the Reserve that could host 1.5 million people.Tijuca
Tijuca (Portuguese pronunciation: [tʃiˈʒukɐ]) (meaning marsh or swamp in the Tupi language, from ty ("water") and îuká ("to kill")) is a neighbourhood of the Northern Zone of the city of Rio de Janeiro, Brazil. It comprises the region of Saens Peña and Afonso Pena squares. According to the 2000 Census, the district has close to 150,000 inhabitants. It borders with Praça da Bandeira, Maracanã, Vila Isabel, Andaraí, Grajaú and Alto da Boa Vista neighbourhoods.
It is one of the most traditional districts of Rio de Janeiro and has the third largest urban forest in the world, the Tijuca Forest, which is result of reforestation from coffee fields that led to lack of water at that time. Mainly a middle class district, it has been historically inhabited by Portuguese immigrant families and the families of military officers.
Tijuca hosts Salgueiro, Império da Tijuca and Unidos da Tijuca, three of the main Rio de Janeiro Samba Schools, that together have won 13 titles.
Tijuca is also home to many favelas such as Salgueiro, Borel, Formiga, Turano and Casa Branca.Tijuca Forest
The Tijuca Forest (Portuguese: Floresta da Tijuca) is a tropical rainforest in the city of Rio de Janeiro, Brazil. It is claimed to be the world's largest urban forest, covering some 32 km² (12.4 mi²), although there are sources assigning this title to the urban forest of Johannesburg, South Africa, where between 6 and 9.5 million trees were planted. Similar to Rio de Janeiro's Tijuca Forest, the UNESCO World Heritage Site Singapore Botanic Gardens (established in 1859) is another renowned garden with a tropical rainforest within its city limits.Tonto National Forest
The Tonto National Forest, encompassing 2,873,200 acres (1,162,700 ha; 11,627 km2), is the largest of the six national forests in Arizona and is the fifth largest national forest in the United States. The Tonto National Forest has diverse scenery, with elevations ranging from 1,400 feet (427 m) in the Sonoran Desert to 7,400 feet (2,256 m) in the ponderosa pine forests of the Mogollon Rim (pronounced MOH-gee-on, or MUH-gee-own). The Tonto National Forest is also the most visited "urban" forest in the United States. The boundaries of the Tonto National Forest are the Phoenix metropolitan area to the south, the Mogollon Rim to the north and the San Carlos and Fort Apache Indian Reservation to the east. The Tonto (Spanish for "dumb") is managed by the USDA Forest Service and its headquarters are in Phoenix. There are local ranger district offices in Globe, Mesa, Payson, Roosevelt, Scottsdale, and Young.Toronto ravine system
The Toronto ravine system is one of the most distinctive features of the geography of Toronto, Ontario, Canada. It is a network of deep ravines that form a large urban forest that runs throughout much of the city. For the most part designated as parkland, the ravines are largely undeveloped. Toronto's slogan: "The city within a park" partially stems from the extensive ravine green space.Urban forestry
Urban forestry is the care and management of single trees and tree populations in urban settings for the purpose of improving the urban environment. Urban forestry advocates the role of trees as a critical part of the urban infrastructure. Urban foresters plant and maintain trees, support appropriate tree and forest preservation, conduct research and promote the many benefits trees provide. Urban forestry is practiced by municipal and commercial arborists, municipal and utility foresters, environmental policymakers, city planners, consultants, educators, researchers and community activists.Urban reforestation
Urban reforestation is the practice of planting trees, typically on a large scale, in urban environments. It sometimes includes also urban horticulture and urban farming. Reasons for practicing urban reforestation include urban beautification, increasing shade, modifying the urban climate, improving air quality, and restoration of urban forests after a natural disaster.West Seattle
West Seattle comprises two of the thirteen districts of the city of Seattle, Washington (Delridge and Southwest) and encompasses all of Seattle west of the Duwamish River. It was incorporated as an independent town in 1902 before being annexed by Seattle five years later. Among the area's attractions are its saltwater beach parks along Elliott Bay and Puget Sound, including Alki Beach Park and Lincoln Park. The area is also known for its views of the Olympic Mountains to the west and the Cascade Range to the east. One-third of Seattle's green space and urban forest is located in West Seattle, much of it in the West Duwamish Greenbelt.