urban ecology
   HOME

TheInfoList



OR:

Urban ecology is the scientific study of the relation of living organisms with each other and their surroundings in an urban environment. An urban environment refers to environments dominated by high-density residential and commercial buildings, paved surfaces, and other urban-related factors that create a unique landscape. The goal of urban ecology is to achieve a balance between human culture and the natural environment. Urban ecology is a recent field of study compared to ecology. Currently, most of the information in this field is based on the easier to study species of mammals and birds ource needed To close the gap in knowledge, attention should be paid to all species in the urban space like insects and fish. This study should also expand to suburban spaces with its unique mix of development and surrounding nature. The methods and studies of urban ecology is a subset of ecology. The study of urban ecology carries increasing importance because more than 50% of the world's population today lives in urban areas. It is also estimated that within the next 40 years, two-thirds of the world's population will be living in expanding urban centers. The ecological processes in the urban environment are comparable to those outside the urban context. However, the types of urban
habitats In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
and the species that inhabit them are poorly documented which is why more research should be done in urban ecology.


History

Historically, ecology has focused on natural environments, but by the 1970s many ecologists began to turn their interest towards ecological interactions taking place in and caused by urban environments. In the nineteenth century, naturalists such as
Malthus Thomas Robert Malthus (; 13/14 February 1766 – 29 December 1834) was an English economist, cleric, and scholar influential in the fields of political economy and demography. In his 1798 book ''An Essay on the Principle of Population'', Mal ...
, De Candolle, Lyell, and Darwin found that competition for resources was crucial in controlling population growth and is a driver of extinction. This concept was the basis of evolutionary ecology. Jean-Marie Pelt's 1977 book ''The Re-Naturalized Human'', Brian Davis' 1978 publication ''Urbanization and the diversity of insects'', and Sukopp et al.'s 1979 article "The soil, flora and vegetation of Berlin's wastelands" are some of the first publications to recognize the importance of urban ecology as a separate and distinct form of ecology the same way one might see
landscape ecology Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizatio ...
as different from
population ecology Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment (biophysical), environment, such as birth rate, birth and death rates, and by immigration an ...
. Forman and Godron's 1986 book ''Landscape Ecology'' first distinguished urban settings and landscapes from other landscapes by dividing all landscapes into five broad types. These types were divided by the intensity of human influence ranging from pristine
natural environment The natural environment or natural world encompasses all life, biotic and abiotic component, abiotic things occurring nature, naturally, meaning in this case not artificiality, artificial. The term is most often applied to Earth or some parts ...
s to
urban centers An urban area is a human settlement with a high population density and an infrastructure of built environment. Urban areas originate through urbanization, and researchers categorize them as cities, towns, conurbations or suburbs. In urbani ...
. Early ecologists defined ecology as the study of organisms and their environment. As time progressed urban ecology was recognized as a diverse and complex concept which differs in application between North America and Europe. The European concept of urban ecology examines the biota of urban areas, the North American concept has traditionally examined the social sciences of the urban landscape, as well as the ecosystem fluxes and processes, and the Latin American concept examines the effect of human activity on the biodiversity and fluxes of urban ecosystems. A renaissance in the development of urban ecology occurred in the 1990s that was initiated by the US National Science in funding two urban long-term ecological research centers and this promoted the study of urban ecology. The field of urban ecology is rapidly expanding, with an increasing number of dedicated research centers emerging. Among the pioneers are the Urban Ecology Research Laboratory (UERL) at the University of Washington, established in 2001, and the Urban Ecology Laboratory (LEU) at the Costa Rican Distance University, founded in 2008. The UERL in Washington specializes in analyzing urban landscape patterns, ecosystem functions, modeling land cover changes, and developing scenarios for urban adaptation within the state. In contrast, Costa Rica's LEU holds distinction as the world's first research center exclusively devoted to studying tropical urban ecosystems. Research conducted there spans various facets of urban ecology, including biodiversity, the impacts of
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
on cities and their surrounding areas (particularly tropical highlands), and the intricate interactions between human activities and urban environments.


Methods

Since urban ecology is a subfield of ecology, many of the techniques are similar to that of ecology. Ecological study techniques have been developed over centuries, but many of the techniques use for urban ecology are more recently developed. Methods used for studying urban ecology involve chemical and biochemical techniques, temperature recording, heat mapping
remote sensing Remote sensing is the acquisition of information about an physical object, object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring inform ...
, and long-term ecological research sites.


Chemical and biochemical techniques

Chemical techniques may be used to determine
pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...
concentrations and their effects. Tests can be as simple as dipping a manufactured test strip, as in the case of pH testing, or be more complex, as in the case of examining the spatial and temporal variation of heavy metal contamination due to industrial runoff. In that particular study, livers of birds from many regions of the
North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...
were ground up and mercury was extracted. Additionally, mercury bound in feathers was extracted from both live birds and from museum specimens to test for mercury levels across many decades. Through these two different measurements, researchers were able to make a complex picture of the spread of mercury due to industrial runoff both spatially and temporally. Other chemical techniques include tests for
nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
s,
phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...
s,
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
s, etc. which are commonly associated with urban
pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...
s such as
fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
and industrial byproducts. These biochemical fluxes are studied in the atmosphere (e.g.
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es),
aquatic ecosystem An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environ ...
s and soil nematodes. Broad reaching effects of these biochemical fluxes can be seen in various aspects of both the urban and surrounding rural ecosystems.


Temperature data and heat mapping

Temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
data can be used for various kinds of studies. An important aspect of temperature data is the ability to correlate temperature with various factors that may be affecting or occurring in the environment. Oftentimes, temperature data is collected long-term by the
Office of Oceanic and Atmospheric Research Oceanic and Atmospheric Research (OAR) is a division of the National Oceanic and Atmospheric Administration (NOAA). OAR is also referred to as NOAA Research. NOAA Research is the research and development arm of NOAA and is the driving force beh ...
(OAR), and made available to the scientific community through the
National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with Weather forecasting, forecasting weather, monitoring oceanic and atmospheric conditions, Hydrography, charting the seas, ...
(NOAA). Data can be overlaid with maps of terrain, urban features, and other spatial areas to create heat maps. These heat maps can be used to view trends and distribution over time and space.


Remote sensing

Remote sensing Remote sensing is the acquisition of information about an physical object, object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring inform ...
is the technique in which data is collected from distant locations through the use of satellite imaging,
radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
, and aerial photographs. In urban ecology, remote sensing is used to collect data about terrain, weather patterns, light, and vegetation. One application of remote sensing for urban ecology is to detect the productivity of an area by measuring the photosynthetic wavelengths of emitted light. Satellite images can also be used to detect differences in temperature and landscape diversity to detect the effects of urbanization.


LTERs and long-term data sets

Long-term ecological research (LTER) sites are research sites funded by the government that have collected reliable long-term data over an extended period of time in order to identify long-term climatic or ecological trends. These sites provide long-term temporal and spatial data such as average temperature, rainfall and other ecological processes. The main purpose of LTERs for urban ecologists is the collection of vast amounts of data over long periods of time. These long-term data sets can then be analyzed to find trends relating to the effects of the urban environment on various ecological processes, such as species diversity and abundance over time. Another example is the examination of temperature trends that are accompanied with the growth of urban centers. There are currently two active urban LTERs: Central Arizona-Phoenix (CAP), first launched in 1997 and housed at
Arizona State University Arizona State University (Arizona State or ASU) is a public university, public research university in Tempe, Arizona, United States. Founded in 1885 as Territorial Normal School by the 13th Arizona Territorial Legislature, the university is o ...
and Minneapolis-St. Paul Metropolitan Area (MSP). The Baltimore Ecosystem Study (BES) was originally funded in 1998 as an urban LTER but as is no longer funded by the National Science Foundation as of 2021.


Urban effects on the environment

Humans are the driving force behind urban ecology and influence the environment in a variety of ways - urbanization being a key example. Urbanization is tied to social, economic and environmental processes. There are six core aspects: air pollution, ecosystems, land use, biogeochemical cycles, water pollution, solid waste management, and the climate. Urbanization was driven by migration into cities and the rapid environmental implications that came with it; increased carbon emissions, energy consumption, impaired ecology; all primarily negative. Despite the impacts, the perception of urbanization at present is shifting from challenges to solutions. Cities are home to an abundant amount of financially well-off, knowledgeable and innovative initiators who are increasing the involvement of science in urban policy processes and concepts. The intersection of the multiple processes/integrated systems approach which can easily emerge within a city, includes five characteristics that can emphasize this fundamental shift at a low cost. These solutions are integrated, comprehensive, multifunctional approaches that speak to the social, economic, and cultural contexts of cities. They take into account the chemical, biophysical, and ecological aspects that define urban systems, including lifestyle choices that are interlinked with the culture of a city. However, despite adapting the opportunities that a city can participate in, the results of the concepts that researchers have developed remains uncertain.


Modification of land and waterways

Humans place high demand on land not only to build urban centers, but also to build surrounding suburban areas for housing. Land is also allocated for agriculture to sustain the growing population of the city. Expanding cities and suburban areas necessitate corresponding deforestation to meet the land-use and resource requirements of urbanization. Key examples of this are
Deforestation in the United States In the United States, deforestation was an ongoing process until recently. Between 2010 and 2020, the US forests increased 0.03% annually, according to FAO (Food and Agriculture Organization, Food and Agriculture Organization of the United Nations ...
and
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
. Along with manipulation of land to suit human needs, natural water resources such as rivers and streams are also modified in urban establishments. Modification can come in the form of dams, artificial canals, and even the reversal of rivers. Reversing the flow of the Chicago River is a major example of urban environmental modification.Hill, L. The Chicago River: A Natural and Unnatural History. Lake Claremont Press. 2000. Urban areas in natural desert settings often bring in water from far areas to maintain the human population and will likely have effects on the local desert climate. Modification of aquatic systems in urban areas also results in decreased stream diversity and increased pollution.


Trade, shipping, and spread of invasive species

Both local shipping and long-distance trade are required to meet the resource demands important in maintaining urban areas.
Carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
emissions from the transport of goods also contribute to accumulating greenhouse gasses and nutrient deposits in the soil and air of urban environments. In addition, shipping facilitates the unintentional spread of living organisms, and introduces them to environments that they would not naturally inhabit. Introduced or
alien species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...
are populations of organisms living in a range in which they did not naturally evolve due to intentional or inadvertent human activity. Increased transportation between urban centers furthers the incidental movement of animal and plant species. Alien species often have no natural predators and pose a substantial threat to the dynamics of existing ecological populations in the environment into which they are introduced.
Invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...
are successful when they are able to have proliferate reproduction due to short life cycles, contain or adapt to have traits that suit the environment and appear in high densities. Such invasive species are numerous and include
house sparrow The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pa ...
s,
ring-necked pheasant The common pheasant (''Phasianus colchicus''), ring-necked pheasant, or blue-headed pheasant, is a bird in the pheasant family (Phasianidae). The genus name comes from Latin ''phasianus'' 'pheasant'. The species name ''colchicus'' is Latin for ...
s,
European starling The common starling (''Sturnus vulgaris''), also known simply as the starling in Great Britain and Ireland, and as European starling in North America, is a medium-sized passerine bird in the starling family, Sturnidae. It is about long and ha ...
s,
brown rat The brown rat (''Rattus norvegicus''), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat and Norwegian rat, is a widespread species of common rat. One of the largest Muroidea, muroids, it is a brown or grey ...
s, Asian carp, American bullfrogs, emerald ash borer,
kudzu Kudzu (), also called Japanese arrowroot or Chinese arrowroot, is a group of climbing, coiling, and trailing deciduous perennial vines native to much of East Asia, Southeast Asia, and some Pacific islands. It is invasive species, invasive in ...
vines, and
zebra mussels The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...
among numerous others, most notably domesticated animals. Brown rats are a highly invasive species in urban environments, and are commonly seen in the streets and subways of New York City, where they pose multiple negative effects to infrastructure, native species and human health. Brown rats carry several types of parasites and pathogens that can possibly infect humans and other animals. In New York City a genetic study exploring genome wide variation concluded that multiple rats were originally from Great Britain. In Australia, it has been found that removing Lantana ('' L. camara,'' an alien species) from
urban green space In land-use planning, urban green spaces are open-space areas reserved for parks and other "green spaces." These include plant life, water features also known as blue spaces and other kinds of natural environments. Most urban open spaces a ...
s can have negative impacts on bird diversity locally, as it provides refugia for species like the superb fairy ( Malurus cyaneus) and silvereye ( Zosterops lateralis), in the absence of native plant equivalents. Although, there seems to be a density threshold in which too much
Lantana ''Lantana'' () is a genus of about 150 species of perennial plant, perennial flowering plants in the verbena family, Verbenaceae. They are native to tropics, tropical regions of the Americas and Africa but exist as an introduced species in num ...
(thus homogeneity in vegetation cover) can lead to a decrease in bird species richness or abundance.


Effects of urban animals on humans


Positive effects

Some urban animals can have a positive impact on the lives of humans. Studies show that the presence of domestic animals can reduce stress, anxiety and loneliness. Additionally some urban animals act as predators to animals like insects, etc., that can be harmful to humans Also urban species can serve many more purposes including agriculture, transport, and protection.


Negative effects

Some urban species have a negative impact on humans. For example, pests' urine fecal matter, and skin fragments can spread germs if ingested by humans. Diseases caused by pests or insects can be fatal. They include:
salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...
,
meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, intense headache, vomiting and neck stiffness and occasion ...
, Weil's disease,
Lyme disease Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in th ...
, etc. Some people are allergic to certain insects like bees, wasps and therefore being exposed to them will cause serious allergic responses (rashes for example). According to Seth Magle, attacks from wildlife in an urban setting, while rare are detrimental to societal views on wildlife. Due to media coverage of these rare attacks, urban populations assume these interactions as more common than they really are which further affects the tolerance of urban wildlife.


Human effects on biogeochemical pathways

Urbanization results in a large demand for chemical use by industry, construction, agriculture, and energy providing services. Such demands have a substantial impact on biogeochemical cycles, resulting in phenomena such as
acid rain Acid rain is rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists b ...
,
eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...
, and
global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
. Furthermore, natural biogeochemical cycles in the urban environment can be impeded due to impermeable surfaces that prevent nutrients from returning to the soil, water, and atmosphere. Demand for fertilizers to meet agricultural needs exerted by expanding urban centers can alter chemical composition of soil. Such effects often result in abnormally high concentrations of compounds including sulfur, phosphorus, nitrogen, and heavy metals. In addition, nitrogen and phosphorus used in fertilizers have caused severe problems in the form of agricultural runoff, which alters the concentration of these compounds in local rivers and streams, often resulting in adverse effects on native species. A well-known effect of agricultural runoff is the phenomenon of eutrophication. When the fertilizer chemicals from agricultural runoff reach the ocean, an
algal bloom An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in fresh water or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompass ...
results, then rapidly dies off. The dead algae biomass is decomposed by bacteria that also consume large quantities of oxygen, which they obtain from the water, creating a "dead zone" without oxygen for fish or other organisms. A classic example is the dead zone in the
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
due to agricultural runoff into the
Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
. Just as pollutants and alterations in the biogeochemical cycle alter river and ocean ecosystems, they exert likewise effects in the air. Some stems from the accumulation of chemicals and pollution and often manifests in urban settings, which has a great impact on local plants and animals. Because urban centers are often considered point sources for pollution, local plants have adapted to withstand such conditions.


Urban effects on climate

Urban environments and outlying areas have been found to exhibit unique local temperatures,
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
, and other characteristic activity due to a variety of factors such as pollution and altered geochemical cycles. Some examples of the urban effects on climate are
urban heat island Urban areas usually experience the urban heat island (UHI) effect; that is, they are significantly warmer than surrounding rural areas. The temperature difference is usually larger at night than during the day, and is most apparent when winds ar ...
, oasis effect,
greenhouse gases Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
, and
acid rain Acid rain is rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists b ...
. This further stirs the debate as to whether urban areas should be considered a unique
biome A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...
. Despite common trends among all urban centers, the surrounding local environment heavily influences much of the climate. One such example of regional differences can be seen through the urban heat island and oasis effect.


Urban heat island effect

The
urban heat island Urban areas usually experience the urban heat island (UHI) effect; that is, they are significantly warmer than surrounding rural areas. The temperature difference is usually larger at night than during the day, and is most apparent when winds ar ...
is a phenomenon in which central regions of urban centers exhibit higher mean temperatures than surrounding urban areas. Much of this effect can be attributed to low city
albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
, the reflecting power of a surface, and the increased surface area of buildings to absorb solar radiation.
Concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
,
cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
, and metal surfaces in urban areas tend to absorb heat energy rather than reflect it, contributing to higher urban temperatures. Brazel et al. found that the urban heat island effect demonstrates a positive correlation with population density in the city of Baltimore. The heat island effect has corresponding ecological consequences on resident species. However, this effect has only been seen in
temperate climates In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...
.


Greenhouse gases

Emissions of
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es allow humans to inhabit the earth because they capture heat from the sun to make the climate adequate. In 1896, Swedish scientist
Svante Arrhenius Svante August Arrhenius ( , ; 19 February 1859 – 2 October 1927) was a Swedish scientist. Originally a physicist, but often referred to as a chemist, Arrhenius was one of the founders of the science of physical chemistry. In 1903, he received ...
established that fossil fuels caused carbon dioxide emissions (the most abundant and harmful greenhouse gas) . In the 20th century, American climate scientist James E. Hansen concluded that Greenhouse effect is changing the climate for the worse. Carbon dioxide is the most abundant greenhouse gas and accounts for 3/4 of emissions. It is emitted by burning coal, oil, gas, wood, and other organic material. Another greenhouse gas is methane. it can come from landfill, natural gases, and or petroleum industries. Nitrous oxide accounts for about 6% of the emissions, and can come from fertilizers, manure, burning of agricultural residues, and or fuel. Finally, fluorinated gases account for 2% of greenhouse gas emissions and can come from refrigerants, solvents, etc. The excessive emission of greenhouse gases is responsible for much of the harm that can be observed today including global warming, respiratory diseases due to pollution, extinction or migration of certain species, etc. These issues can be reduced if not resolved by eliminating the use of fossil fuels in favor of renewable energy sources.


Acid rain and pollution

Processes related to urban areas result in the emission of numerous pollutants, which change corresponding
nutrient cycle A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...
s of carbon, sulfur, nitrogen, and other elements. Ecosystems in and around the urban center are especially influenced by these point sources of pollution. High
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
concentrations resulting from the industrial demands of urbanization cause rainwater to become more acidic. Such an effect has been found to have a significant influence on locally affected populations, especially in aquatic environments. Wastes from urban centers, especially large urban centers in developed nations, can drive biogeochemical cycles on a global scale.


Urban environment as an anthropogenic biome

The urban environment has been classified as an anthropogenic biome, which is characterized by the predominance of certain species and climate trends such as urban heat island across many urban areas. Examples of species characteristic of many urban environments include, cats, dogs, mosquitoes, rats, flies, and pigeons, which are all generalists. Many of these are dependent on human activity and have adapted accordingly to the niche created by urban centers. However, the large number of wild species being discovered in urban areas around the world suggest that a bewildering diversity of life is able to call urban areas their home. The relationship between urbanisation and wildlife diversity may not be as straightforward as previously imagined. This change in imagination has been possible due to coverage of a much larger number of cities in varied parts of the world that now show that past trends and assumptions were largely due to a bias in coverage of cities in temperate, developed countries.


Biodiversity and urbanization

Research in countries of temperate areas indicates that, on a small scale,
urbanization Urbanization (or urbanisation in British English) is the population shift from Rural area, rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. ...
often increases the
biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...
of non-native species while reducing that of native species. This normally results in an overall reduction in
species richness Species richness is the number of different species represented in an community (ecology), ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the Abundance (ecology), abunda ...
and increase in total biomass and
species abundance In ecology, local abundance is the relative representation of a species in a particular ecosystem. It is usually measured as the number of individuals found per sample. The ratio of abundance of one species to one or multiple other species livin ...
. Urbanization reduces diversity on a large scale in cities of developed countries, but in
tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
and
subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
cities, despite the high human densities, can retain very high diversity if small patches of habitats are retained across the city. Even domestic urban and suburban properties near high density city centres can support well over a thousand macro-organism species, many of which are often native. These urban landscapes can also support many complex ecosystem interactions. However, urbanization disrupts many other species interactions that would occur in undeveloped natural habitat. Urban stream syndrome is a consistently observed trait of urbanization characterized by high nutrient and contaminant concentration, altered stream morphology, increased dominance of dominant species, and decreased biodiversity The two primary causes of urban stream syndrome are storm water runoff and
wastewater treatment Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on ...
plant effluent.


Changes in diversity

Diversity is normally reduced at intermediate-low levels of urbanization but is always reduced at high levels of urbanization. These effects have been observed in vertebrates and invertebrates while plant species tend to increase with intermediate-low levels of urbanization but these general trends do not apply to all organisms within those groups. For example, McKinney's (2006) review did not include the effects of urbanization on fishes and of the 58 studies on invertebrates, 52 included insects while only 10 included spiders. There is also a geographical bias as most of the studies either took place in North America or Europe. The effects of urbanization also depend on the type and range of resources used by the organism. Generalist species, those that use a wide range of resources and can thrive under a large range of living conditions, are likely to survive in uniform environments.
Specialist species A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of en ...
, those that use a narrow range of resources and can only cope with a narrow range of living conditions, are unlikely to cope with uniform environments. There will likely be a variable effect on these two groups of organisms as urbanization alters habitat uniformity. Endangered plant species have been reported to occur throughout a wide range of urban ecosystems, many of them being novel ecosystems. A study of 463 bird species reported that urban species share dietary traits. Specifically, urban species were larger, consumed more vertebrates and
carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
, and fed more frequently on the ground or aerially, and also had broader diets than non‐urban species.


Cause of diversity change

The urban environment can decrease diversity through habitat removal and species homogenization—the increasing similarity between two previously distinct biological communities.
Habitat degradation Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
and
habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...
reduces the amount of suitable habitat by urban development and separates suitable patches by inhospitable terrain such as
road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...
s, neighborhoods, and open parks. Although this replacement of suitable habitat with unsuitable habitat will result in
extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
s of native species, some shelter may be artificially created and promote the survival of non-native species (e.g.
house sparrow The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pa ...
and house mice nests). Urbanization promotes species homogenization through the extinction of native
endemic species Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
and the introduction of non-native species that already have a widespread abundance. Changes to the habitat may promote both the extinction of native endemic species and the introduction of non-native species. The effects of habitat change will likely be similar in all urban environments as urban environments are all built to cater to the needs of humans. Wildlife in cities are more susceptible to suffering ill effects from exposure to toxicants (such as heavy metals and pesticides). In China, fish that were exposed to industrial wastewater had poorer body condition; being exposed to toxicants can increase susceptibility to infection. Humans have the potential to induce patchy food distribution, which can promote animal aggregation by attracting a high number of animals to common food sources; “this aggregation may increase the spread of
parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...
transmitted through close contact; parasite deposition on soil, water, or artificial feeders; and stress through inter‐ and intraspecific competition.” The results of a study performed by Maureen Murray (et al.), in which a phylogenetic meta-analysis of 516 comparisons of overall wildlife condition reported in 106 studies was performed, confirmed these results; “our meta‐analysis suggests an overall negative relationship between urbanization and wildlife health, mainly driven by considerably higher toxicant loads and greater parasite abundance, greater parasite diversity, and/or greater likelihood of infection by parasites transmitted through close contact.” The urban environment can also increase diversity in a number of ways. Many foreign organisms are introduced and dispersed naturally or artificially in urban areas. Artificial introductions may be intentional, where organisms have some form of human use, or accidental, where organisms attach themselves to
transportation Transport (in British English) or transportation (in American English) is the intentional Motion, movement of humans, animals, and cargo, goods from one location to another. Mode of transport, Modes of transport include aviation, air, land tr ...
vehicles. Humans provide food sources (e.g. birdfeeder seeds, trash, garden
compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...
) and reduce the numbers of large natural
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s in urban environments, allowing large populations to be supported where food and predation would normally limit the population size. There are a variety of different habitats available within the urban environment as a result of differences in land use allowing for more species to be supported than by more uniform habitats.


Ways to improve urban ecology: civil engineering and sustainability

Cities should be planned and constructed in such a way that minimizes the urban effects on the surrounding environment (urban heat island, precipitation, etc.) as well as optimizing ecological activity. For example, increasing the
albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
, or reflective power, of surfaces in urban areas, can minimize urban heat island, resulting in a lower magnitude of the urban heat island effect in urban areas. By minimizing these abnormal temperature trends and others, ecological activity would likely be improved in the urban setting.


Need for remediation

Urbanization has indeed had a profound effect on the environment, on both local and global scales. Difficulties in actively constructing habitat corridors and returning
biogeochemical cycle A biogeochemical cycle, or more generally a cycle of matter, is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cyc ...
s to normal raise the question as to whether such goals are feasible. However, some groups are working to return areas of land affected by the urban landscape to a more natural state. This includes using landscape architecture to model natural systems and restore rivers to pre-urban states. It is becoming increasingly critical that conservation action be enacted within urban landscapes. Space in cities is limited; urban infill threatens the existence of green spaces. Green spaces that are in close proximity to cities are also vulnerable to
urban sprawl Urban sprawl (also known as suburban sprawl or urban encroachment) is defined as "the spreading of urban developments (such as houses and shopping centers) on undeveloped land near a city". Urban sprawl has been described as the unrestricted ...
. It is common that urban development comes at the cost of valuable land that could host wildlife species. Natural and financial resources are limited; a larger focus must be placed on conservation opportunities that factor in feasibility and maximization of expected benefits. Since the securing of land as a
protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...
is a luxury that cannot be extensively implemented, alternative approaches must be explored in order to prevent mass extinction of species. Borgström et al. 2006 hold that urban ecosystems are especially prone to "scale mismatch" whereby the right course of action is heavily dependent on species size. For some species conservation can be achieved in a single isolated garden because their small size permits a large population, e.g. soil microorganisms. Meanwhile, that is the wrong scale for species that are more mobile and/or larger, e.g.
pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...
s and seed dispersers, which will require larger and/or connected spaces. The need to pursue conservation outcomes in urban environments is most pronounced for species whose global distribution is contained within a human-modified landscape. The fact is that many threatened wildlife species are prevalent among land types that were not originally intended for conservation. Of Australia's 39 urban-restricted threatened species, 11 species occur at roadsides, 10 species occur in private lands, 5 species occur in military lands, 4 species in schools, 4 species in golf courses, 4 species at utility easements (such as railways), 3 species at airports and 1 species at hospitals. The spiked rice flower species Pimelea spicata persists mainly at a golf course, while the guinea-flower hibbertia puberula glabrescens is known mainly from the grounds of an airport. Unconventional landscapes as such are the ones that must be prioritized. The goal in the management of these areas is to bring about a “win-win” situation where conservation efforts are practiced while not compromising the original use of the space. While being near to large human populations can pose risks to endangered species inhabiting urban environments, such closeness can prove to be an advantage as long as the human community is conscious and engaged in local conservation efforts.


Species reintroduction

Reintroduction of species to urban settings can help improve the local biodiversity previously lost; however the following guidelines should be followed in order to avoid undesired effects. # No
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s capable of killing children will be reintroduced to urban areas. # There will be no introduction of species that significantly threaten human health, pets, crops or property. # Reintroduction will not be done when it implies significant suffering to the organisms being reintroduced, for example stress from capture or captivity. # Organisms that carry
pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s will not be reintroduced. # Organisms whose genes threaten the genetic pool of other organisms in the urban area will not be reintroduced. # Organisms will only be reintroduced when scientific data support a reasonable chance of long-term survival (if funds are insufficient for the long-term effort, reintroduction will not be attempted). # Reintroduced organisms will receive
food supplement A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic ( ...
ation and veterinary assistance as needed. # Reintroduction will be done in both experimental and control areas to produce reliable assessments (monitoring must continue afterwards to trigger interventions if necessary). # Reintroduction must be done in several places and repeated over several years to buffer for stochastic events. # People in the areas affected must participate in the decision process, and will receive education to make reintroduction sustainable (but final decisions must be based on objective information gathered according to scientific standards).


Sustainability

With the ever-increasing demands for resources necessitated by urbanization, recent campaigns to move toward
sustainable energy Energy system, Energy is sustainability, sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." Definitions of sustainable energy usually look at its effects on the e ...
and
resource consumption Resource consumption is about the consumption of non-renewable, or less often, renewable resources. Specifically, it may refer to: * water consumption * energy consumption ** electric energy consumption ** world energy consumption * natural ...
, such as
LEED certification Leadership in Energy and Environmental Design (LEED) is a Green building certification systems, green building certification program used worldwide. Developed by the non-profit U.S. Green Building Council (USGBC), it includes a set of rating ...
of buildings,
Energy Star Energy Star (trademarked ENERGY STAR) is an Efficient energy use, energy-efficiency program established in 1992. It is administered by the U.S. Environmental Protection Agency (EPA) in partnership with the U.S. Department of Energy (DOE). The EPA ...
certified appliances, and
zero emission A zero emission engine, electric motor, motor, process, or other energy source emits no waste products that pollute the environment or disrupt the climate. Zero emission engines Vehicles and other mobile machinery used for transport (over land, sea ...
vehicles, have gained momentum.
Sustainability Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...
reflects techniques and consumption ensuring reasonably low resource use as a component of urban ecology. Techniques such as carbon recapture may also be used to sequester carbon compounds produced in urban centers rather continually emitting more of the
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
. The use of other types of renewable energy like
bioenergy Bioenergy is a type of renewable energy that is derived from plants and animal waste. The Biomass (energy), biomass that is used as input materials consists of recently living (but now dead) organisms, mainly plants. Thus, Fossil fuel, fossil fu ...
,
solar energy Solar energy is the radiant energy from the Sun's sunlight, light and heat, which can be harnessed using a range of technologies such as solar electricity, solar thermal energy (including solar water heating) and solar architecture. It is a ...
,
geothermal energy Geothermal energy is thermal energy extracted from the crust (geology), crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for m ...
, and
wind energy Wind power is the use of wind energy to generate useful work. Historically, wind power was used by sails, windmills and windpumps, but today it is mostly used to generate electricity. This article deals only with wind power for electricity ...
would also help to reduce greenhouse gas emissions.


Green Infrastructure Implementation

Urban areas can be converted to areas that are more conducive to hosting wildlife through the application of
green infrastructure Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature.Hiltrud Pötz & Pierre Bleuze (2011). Urban green-blue grids for sustain ...
. Although the opportunities of green infrastructure (GI) to benefit human populations have been recognized, there are also opportunities to conserve wildlife diversity. Green infrastructure has the potential to support wildlife robustness by providing a more suitable habitat than conventional, “grey” infrastructure as well as aid in stormwater management and air purification. GI can be defined as features that were engineered with natural elements or natural features. This natural constitution helps prevent wildlife exposure to man-made toxicants. Although research on the benefits of GI on biodiversity has increased exponentially in the last decade, these effects have rarely been quantified. In a study performed by Alessandro Filazzola (et al.), 1,883 published manuscripts were examined and meta-analyzed in reference to 33 relevant studies in order to determine the effect of GI on wildlife. Although there was variability in the findings, it was determined that the implementation of GI improved
biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...
compared to conventional infrastructure. In some cases, GI even preserved comparable measures of biodiversity to natural components.


Urban green space

A barrier associated with finding the right amount of urban green space is the variety of space needed by different species to complete their life cycles. This is also compounded with the man-made barriers neighboring green spaces that can restrict movement of certain species from other urban green spaces located nearby. Increasing Wildlife Habitat Connectivity The implementation of wildlife corridors throughout urban areas (and in between wildlife areas) would promote wildlife habitat connectivity. Habitat connectivity is critical for ecosystem health and wildlife conservation yet is being compromised by increasing
urbanization Urbanization (or urbanisation in British English) is the population shift from Rural area, rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. ...
. Urban development has caused green spaces to become increasingly fragmented and has caused adverse effects in genetic variation within species, population abundance and species richness. Urban green spaces that are linked by ecosystem corridors have higher ecosystem health and resilience to global environmental change. Employment of corridors can form an ecosystem network that facilitates movement and dispersal. However, planning these networks requires a comprehensive spatial plan. One approach is to target “shrinking” cities (such as
Detroit, Michigan Detroit ( , ) is the List of municipalities in Michigan, most populous city in the U.S. state of Michigan. It is situated on the bank of the Detroit River across from Windsor, Ontario. It had a population of 639,111 at the 2020 United State ...
, USA) that have an abundance of vacant lots and land that could be repurposed into greenways to provide
ecosystem service Ecosystem services are the various benefits that humans derive from ecosystems. The interconnected living and non-living components of the natural environment offer benefits such as pollination of crops, clean air and water, decomposition of wast ...
s (although even cities with growing populations typically have vacant land as well). However, even cities with high vacancy rates sometimes can present social and environmental challenges. For instance, vacant land that stands on polluted soils may contain heavy metals or construction debris; this must be addressed before the repurposing. Once land has been repurposed for ecosystem services, avenues must be pursued that could allow this land to contribute to structural or functional connectivity. Structural connectivity refers to parts of the landscape that are physically connected. Functional connectivity refers to species-specific tendencies that indicate interaction with other parts of the landscape. Throughout the City of Detroit, spatial patterns were detected that could promote structural connectivity. The research performed by Zhang “integrates
landscape ecology Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizatio ...
and
graph theory In mathematics and computer science, graph theory is the study of ''graph (discrete mathematics), graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of ''Vertex (graph ...
, spatial modeling, and
landscape design Landscape design is an independent profession and a design and art tradition, practiced by landscape designers, combining nature and culture. In contemporary practice, landscape design bridges the space between landscape architecture and garde ...
to develop a methodology for planning multifunctional green infrastructure that fosters social-ecological sustainability and resilience”. Using a functional connectivity index, there was found to be a high correlation between these results (structural and functional connectivity), suggesting that the two metrics could be indicators of each other and could guide green space planning. Although urban wildlife corridors could serve as a potential mitigation tool, it is important that they are constructed so as to facilitate wildlife movement without restriction. As humans may be perceived as a threat, the success of the corridors is dependent on human population density proximity to roads. In a study performed by Tempe Adams (et al.), remote-sensor camera traps and data from GPS collars were utilized to assess whether or not the African elephant would use narrow urban wildlife corridors. The study was performed in three different urban-dominated land use types (in
Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...
, South Africa) over a span of two years. The results of the study indicated that elephants tended to move through unprotected areas more quickly, spending less time in those areas. Using vehicular traffic as a measure of human activity, the study indicated that elephant presence was higher during times when human activity was at a minimum. It was determined that “formal protection and designation of urban corridors by the relevant governing bodies would facilitate coexistence between people and wildlife at small spatial scales.” However, the only way this co-existence could be feasible is by creating structural connectivity (and thus promoting functional connectivity) by implementing proper wildlife corridors that facilitate easy movement between habitat patches. The usage of
green infrastructure Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature.Hiltrud Pötz & Pierre Bleuze (2011). Urban green-blue grids for sustain ...
that is connected to natural habitats has been shown to reap greater biodiversity benefits than GI implemented in areas far from natural habitats. GI close to natural areas may also increase functional connectivity in natural environments. Roadkill Mitigation In the United States,
roadkill Roadkill is a wild animal that has been killed by collision with motor vehicles. Wildlife-vehicle collisions (WVC) have increasingly been the topic of academic research to understand the causes, and how they can be mitigated. History Essenti ...
takes the lives of hundreds of thousands to hundreds of millions of mammals, birds and amphibians each year. Roadkill mortality has detrimental effects on the persistence probability, abundance and genetic diversity of wildlife populations (more so than reduced movement through habitat patches). Roadkill also has an effect on driver safety. If green areas cannot be reserved, the presence of wildlife habitats in close proximity to urban roads must be addressed. The optimal situation would be to avoid constructing roads next to these natural habitats, but other preventative measures can be pursued to reduce animal mortality. One way these effects could be mitigated is through implementation of wildlife fencing in prioritized areas. Many countries utilize underpasses and overpasses combined with wildlife fencing to reduce roadkill mortality in an attempt to restore habitat connectivity. It is unrealistic to try to fence entire road networks because of financial constraints. Therefore, areas in which the highest rates of mortality occur should be focused on.


Indigenous knowledge

Urban sprawl is one of many ways that Indigenous people's land is taken and developed in cities of the global north, thus the intimate knowledge of the native area (ecology) is often lost due to the effects of
colonization 475px, Map of the year each country achieved List of sovereign states by date of formation, independence. Colonization (British English: colonisation) is a process of establishing occupation of or control over foreign territories or peoples f ...
or because the land has been majorly altered. Urban development occurs around areas where Indigenous Peoples lived as these areas are easy for transport and the natural environmental is fruitful. When developing areas of urban land, consideration should go towards the intimate levels of knowledge held by Indigenous Peoples and the biocultural and
linguistic diversity Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed forms, and may also be conveyed through writing. Human language is ch ...
of the place. Urban ecology follows western science frameworks and compartmentalizes nature. Urban ecology has the opportunity to be viewed in an interconnected and holistic way, through " Two-Eyed Seeing" and be inclusive of the
Traditional Ecological Knowledge Traditional ecological knowledge (TEK) is a cumulative body of knowledge, practice, and belief, evolving by adaptive processes and handed down through generations by cultural transmission, about the relationship of living beings (including humans ...
held by the local Indigenous Peoples of the area. Urban restoration ecology would be enriched by partnerships with the local Indigenous Peoples, if done in a respectful way that addresses the currently inequitable relationship. Non-indigenous people can support their local Indigenous communities by learning about the history of the land and ecosystems that is being restored or studied.
Ecological restoration Ecological restoration, or ecosystem restoration, is the process of assisting the recovery of an ecosystem that has been degraded, damaged, destroyed or transformed. It is distinct from conservation in that it attempts to retroactively repair ...
built with strong Indigenous partnerships benefits the Indigenous culture and identity, as well as all urban dwellers.


Summary

Urbanization results in a series of both local and far-reaching effects on
biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...
,
biogeochemical cycle A biogeochemical cycle, or more generally a cycle of matter, is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cyc ...
s,
hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...
, and
climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...
, among other stresses. Many of these effects are not fully understood, as urban ecology has only recently emerged as a scientific discipline and more research remains to be done. Research on cities outside the US and Europe remains limited. Observations on the impact of urbanization on biodiversity and species interactions are consistent across many studies but definitive mechanisms have yet to be established. Urban ecology constitutes an important and highly relevant subfield of ecology, and further study must be pursued to more fully understand the effects of human urban areas on the environment.


See also

* Blue space *
Carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
*
Circles of Sustainability Circles of Sustainability is a method for understanding and assessing sustainability, and for project management directed towards socially sustainable outcomes. It is intended to handle 'seemingly intractable problems' such as outlined in sustai ...
*
Climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
* Green track *
Greenway (landscape) A greenway is usually a shared-use path along a strip of undeveloped land, in an urban or rural area, set aside for recreational use or environmental protection. Greenways are frequently created out of Rail trails, disused railways, canal towpat ...
*
Habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
*
Landscape ecology Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizatio ...
*
Settlement geography Settlement geography is a branch of human geography that investigates the Earth's surface's part settled by humans. According to the United Nations' Vancouver Declaration on Human Settlements (1976), "human settlements means the totality of ...
*
Urban economics Urban economics is broadly the economic study of urban areas; as such, it involves using the tools of economics to analyze urban issues such as crime, education, public transit, housing, and local government finance. More specifically, it is a bra ...
*
Urban forest inequity Urban forest inequity, also known as shade inequity or tree canopy inequity, is the inequitable distribution of trees, with their associated benefits, across metropolitan areas. This phenomenon has a number of follow-on effects, including but not li ...
*
Urban forest Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities Urban may also refer to: General * Urban (name), a list of peop ...
*
Urban forestry Urban forestry is the care and management of single trees and tree populations in Urban area, urban settings for the purpose of improving the urban environment. Urban forestry involves both planning and management, including the programming of ...
*
Urban geography Urban geography is the subdiscipline of geography that derives from a study of cities and urban processes. Urban geographers and urbanists examine various aspects of urban life and the built environment. Scholars, activists, and the public have ...
*
Urban green space In land-use planning, urban green spaces are open-space areas reserved for parks and other "green spaces." These include plant life, water features also known as blue spaces and other kinds of natural environments. Most urban open spaces a ...
*
Urban park An urban park or metropolitan park, also known as a city park, municipal park (North America), public park, public open space, or municipal gardens (United Kingdom, UK), is a park or botanical garden in cities, densely populated suburbia and oth ...
*
Urban studies Urban studies is based on the study of the urban development of cities and regions—it makes up the theory portion of the field of urban planning. This includes studying the history of city development from an architectural point of view, to th ...
*
Wildlife corridor A wildlife corridor, also known as a habitat corridor, or green corridor, is a designated area habitat (ecology), that connects wildlife populations that have been separated by human activities or structures, such as development, roads, or land ...
*
Zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...


References

{{DEFAULTSORT:Urban ecology Human ecology Urban planning Ecology by biome