The Transformative Power of Urban Ecology

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. (EPA Smart Growth)

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 [source 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 and the species that inhabit them are poorly documented which is why more research should be done in urban ecology. (HUD Community Planning)

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, 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 Herbert 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 as different from population ecology. 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 environments to urban centers.[better source needed] (USDA National Agriculture Library)

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. (EPA Environmental Resources)

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 on cities and their surrounding areas (particularly tropical highlands), and the intricate interactions between human activities and urban environments. (University of Minnesota Extension)

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, and long-term ecological research sites. (Penn State Extension)

Chemical techniques may be used to determine pollutant 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 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. (EPA Smart Growth)

Other chemical techniques include tests for nitrates, phosphates, sulfates, etc. which are commonly associated with urban pollutants such as fertilizer and industrial byproducts. These biochemical fluxes are studied in the atmosphere (e.g. greenhouse gases), aquatic ecosystems and soil nematodes. Broad reaching effects of these biochemical fluxes can be seen in various aspects of both the urban and surrounding rural ecosystems. (HUD Community Planning)

Temperature 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 (OAR), and made available to the scientific community through the National Oceanic and Atmospheric Administration (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. (USDA National Agriculture Library)

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. (EPA Environmental Resources)

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 and Europe. (University of Minnesota Extension)

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. 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. (Penn State Extension)

Both local shipping and long-distance trade are required to meet the resource demands important in maintaining urban areas. Carbon dioxide 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 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 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 sparrows, ring-necked pheasants, European starlings, brown rats, Asian carp, American bullfrogs, emerald ash borer, kudzu vines, and zebra mussels 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 spaces 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 (thus homogeneity in vegetation cover) can lead to a decrease in bird species richness or abundance. (EPA Smart Growth)

Urban effects on climate

Urban environments and outlying areas have been found to exhibit unique local temperatures, precipitation, 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, oasis effect, greenhouse gases, and acid rain. This further stirs the debate as to whether urban areas should be considered a unique biome. 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. (HUD Community Planning)

The urban heat island 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, the reflecting power of a surface, and the increased surface area of buildings to absorb solar radiation. Concrete, cement, 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. (USDA National Agriculture Library)

Emissions of greenhouse gases allow humans to inhabit the earth because they capture heat from the sun to make the climate adequate. In 1896, Swedish scientist Svante Arrhenius 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. (EPA Environmental Resources)

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. (University of Minnesota Extension)

Biodiversity and urbanization

Research in countries of temperate areas indicates that, on a small scale, urbanization often increases the biodiversity of non-native species while reducing that of native species. This normally results in an overall reduction in species richness and increase in total biomass and species abundance. Urbanization reduces diversity on a large scale in cities of developed countries, but in tropical and subtropical 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. (Penn State Extension)

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 plant effluent. (EPA Smart Growth)

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. (HUD Community Planning)

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, 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. (USDA National Agriculture Library)

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, 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. (EPA Environmental Resources)

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 cycles 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. (University of Minnesota Extension)

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. 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 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. pollinators and seed dispersers, which will require larger and/or connected spaces. (Penn State Extension)

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. (EPA Smart Growth)

Related Reading

• The Transformative Power of Sustainable Education
• Reviving Eden: The Transformative Power of Native Plant Restoration
• Cultivating a Community Garden: The Transformative Power
• Cultivating Community Gardens: The Transformative Power

Frequently Asked Questions

What is the most important thing to know about Urban ecology?

The most important factor is starting with an honest assessment of your current situation and available resources. Effective implementation depends on matching the approach to your specific context — climate, scale, community, and goals all matter. (HUD Community Planning)

Conclusion

The Transformative Power of Urban Ecology represents an important dimension of the larger shift toward sustainable, ecologically grounded ways of living. Whether you are just beginning or deepening existing practice, the resources and knowledge are increasingly accessible. The steps taken today — however modest — contribute to a compounding body of change that matters both locally and globally. (USDA National Agriculture Library)

Additional reference: Wikipedia — Urban ecology

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