This image shows what the urban ecosystem involves.

Understanding Urban Ecosystems as a Conceptual Relationship Between Humans and the Environment

The urban ecosystem is a relatively new concept. When people talk about the environment, they tend to talk about humanity as separate from it. In fact, the relationship between humans and the environment is only now coming to the forefront of research. Studies of concepts like ecofeminism and environmental justice capture this relationship. Humans are deeply connected to the environment because they are a part of it. Consequently, humans shape and change the environment just as it shapes and changes them.

One prime example of this relationship occurs in cities. Cities and other urban areas house approximately half of the world’s population. According to the United Nations, within the next two decades, sixty percent of the world will live in urban areas. These urban areas have entire ecosystems with their own rules. In order to sustain this number of people in a healthy environment, people need to understand these ecosystems. Contrary to popular belief, studies show that these areas are not separate from nature, but new ecological niches. These are known as urban ecosystems.

Climate, pollution, and water management are unique facets of urban ecosystems. They behave in certain ways only in cities because of the particular circumstances that present themselves in urban areas. Attempting to approach these ideas without considering the role that urbanization plays would be detrimental. By working to understand these ecosystems, researchers can determine solutions to help both humans and their environment.


This graph shows how climate changes in rural and urban areas.
Image Source: Leslie Stewart

Urban Heat Islands

Urban areas have unique climates. Buildings and dense human populations, among other factors, create a particular environment. The urban heat island (UHI) effect describes the distinct climates of cities. Urban areas tend to be warmer than the surrounding environment during the night. Because of paved surfaces, dense structures, dark building materials, and human activity, cities generate more heat. Additionally, pollution in urban areas creates boundary layers of air that keep the heat locked in.

The heat produced by urban areas can be incredibly dangerous. It can increase the effects of naturally occurring heatwaves. Vulnerable portions of the population, like the elderly and children, experience heat-related illness or death. For example, in the 2003 European heatwave, the amount of people that died in cities numbered in the hundred thousands. The combined effect of UHI and increased temperatures creates a deadly environment that affects the health of human populations.

Human actions and the building of urban areas trap heat and pollution in the atmosphere. In return, the anthropological effects of these climate changes affect human health and livelihood. By understanding the urban ecosystem as a whole, scientists can develop solutions to urban heat islands.

Managing the Climate

One way to manage the heat is by establishing green spaces. In Frankfurt, Germany, green spaces serve to cool down urban areas by about 3 degrees Celsius. The convection of urban heat islands combined with green spaces distributes the heat and allows cool air to flow.

However, simply adding green spaces does not always work. People have to take the surrounding environment into account. For example, London and Bath in England both have compact layouts. This city design decreases heat loss in these areas because of their location in a cold region. Valencia, Spain, on the other hand, has many courtyards that encourage cooling because of its location in a warm and dry climate.

Another method to reduce the effects of urban heat islands is to institute “lightening” streets. Because most building materials are dark, like steel or asphalt, they absorb heat. Several cities are attempting to cover these dark materials with gray coats in order to make the surfaces more reflective. These changes could significantly reduce the effects of the urban heat islands.

Additionally, the combination of the city layout and green spaces creates a manageable climate. Convection is an important contributor to urban heat islands. It causes hot air to rise and cold air to sink in a circular fashion. That way, the heat is perpetually trapped in cities. Understanding convection can help to reduce heat in cities. However, it only works properly with a varied landscape. Ho Chi Minh in Vietnam serves as an example. Small buildings followed by large buildings surround green spaces. As a result, the different sizes of buildings break up the boundary layers and allow heat to escape.


This shows how air pollution enters the atmosphere in urban areas
Image Source: NRDC

New technology and rapid urbanization generate several kinds of pollution that impact urban ecosystems. Light pollution, air pollution, and noise pollution, among others, affect urban areas.

Noise Pollution

Noise pollution is a problem in urban areas. Cars, human activity, and construction disrupt communication and repel species from areas with loud noise. Exposure to constant loud noise can cause health issues. For example, high blood pressure, heart disease, sleep disturbances, and stress occur in humans.

Urban green spaces disperse noise pollution to an extent. Plants and trees act as buffers to absorb sound waves. In Rotterdam, Netherlands, a study evaluated the effect of green spaces. Noise reduction depended on the distance from the source of noise and the type of plants present. Plants with non-wood stems, like carrots and parsnips, were the most effective. The vegetation decreased wind speed and increased the absorption of soil. As a result, this encouraged noise reduction.

Light Pollution

Light pollution creates a new ecological niche that affects how creatures function. Artificial light can affect the circadian rhythms of biological creatures, including humans. It disrupts patterns and replaces natural sources of light. It affects the spread and number of species in urban environments. Light pollution also completely changes the composition of the ecosystem.

According to the BBC, more than 80% of the world’s population lives under light-polluted skies. Almost all of that light pollution comes from cities. Most people do not experience proper night-vision because of the constant light from houses, streetlights, and other artificial sources.

Light in urban areas is necessary. It allows people to move around at night and conduct their business. Therefore, completely getting rid of lights is not a feasible option. Instead, the goal should be to reduce light pollution. The most effective method for reducing light pollution is simply turning off unnecessary lights. Other methods include using LED lights or avoiding the use of blue lights at night.

Air Pollution

The most persistent type of pollution generated by urban areas is air pollution. Waste treatment, industry, and transport all contribute to bad air quality. Additionally, the urban heat island effect also contributes to air pollution. It traps the pollutants in the atmosphere and pushes them downward.

In urban areas, about seven million people die from air pollution-related illnesses around the world. In India, approximately a third of the deaths each year are due to air pollution. Most of these deaths come from heavily populated cities like New Delhi. China contains sixteen of the twenty most polluted cities. The country is one of the largest consumers of fossil fuels in the world. The rapid industrialization and urbanization of these countries places them at the top of air pollution charts.

Pollution, by nature, is more present in urban areas. There are tons of people and activities that create pollution. By researching the interaction between human activities and the ecosystem, scientists have developed several concepts to reduce the different forms of pollution.

To reduce air pollution, cities can limit human activities. For example, Europe plans to ban diesel by 2025. The layout of cities can also help reduce air pollution. Varied landscapes and surface roughness creates a flow of air rather than compression of it. For example, the London Shard is a particularly large building surrounded by smaller buildings. Its height allows it to puncture the boundary layer of air and disperse pollution and airflow.

Water and Overflow

This shows how water tends to overflow in cities.
Image Source: Lake Superior Streams

Another aspect unique to urban ecosystems is water management. The development of urban areas increases flow rates and the chances of flash floods. This stems from the clearing of land for buildings as well as other activities. Without any plants to store water and a lack of surface roughness, runoff and flooding tend to occur. Additionally, urban areas also experience more rainfall because of convection clouds pushing everything towards the ground. Overflow in sewer systems reduces the oxygen in bodies of water, affecting human and wildlife health.

There are three potential solutions to flooding in urban ecosystems. The first refers to control of water at its source. It allows the absorption of water and relieves stress on drains and sewers. Urban areas known as sponge cities work in this manner. They slow, spread, sink, and store water runoff through permeable paths and roads. As a result, this manages the quality and quantity of water through natural water treatments.

The second solution focuses on water as it travels to collection points. This involves building drainage ditches and depressions in the ground. Therefore, water collects in designated areas instead of overflowing.

The third solution to water overflow involves regional control and operating on a wider scale. It diverts streams into rivers and controls their flow to prevent flooding in urban areas.

These three solutions vary depending on specific factors pertaining to each city. Each urban ecosystem is unique and requires different methods for water management.

Practical Applications of Water Management in Urban Areas

Zhuanghe in China works as an experimental sponge city. It has an underground reservoir and natural wastewater treatment. It uses permeable concrete to absorb water and prevent runoff. The city also promotes planting grass and creating roof gardens. Roof gardens can absorb up to 80 percent of the rain that falls onto them. In addition, they also keep the city cooler by dispersing heat.

Beijing implements some eco-city guidelines on how to regulate water and waste. Eco-cities use less resources and use renewable energy. They are sustainable urban areas. Beijing harvests rainwater and regulates water using sensors. It also separates waste water into gray and brown water. This keeps the water from becoming polluted.

Rotterdam in the Netherlands is a resilient city. This means that it has the ability to recover and prepare for future shocks. In this case, it refers to environmental sustainability. Rotterdam has no slopes which prevents runoff. Urban green spaces capture rain and store it in leaves. Approximately 29.2 percent of the natural area of Rotterdam are bodies of water. These areas regulate runoff and, therefore, prevent overflow.

The King’s Sedgemoor Drain in Somerset, England diverts the River Cary into the River Parett. This employs the third water management solution by managing the source of water. The drain empties the moors and prevents flooding in urban areas.

Bodies of water behave differently in non-urban and urban areas. There are a variety of factors that apply to cities that are not present in non-urban areas. Human interaction with bodies of water, specifically, is different in cities.  It is important to understand how water operates in urban areas and the effect it has on humans. This allows people to develop new methods of water conservation and create a sustainable urban ecosystem.


Example of a Chinese Eco-City
Image Source: Mauritius Images GmbH

The rise of urban ecosystems creates unique effects on its inhabitants and the environment. The more people that inhabit cities, the more issues that arise. Urban ecosystems take into account human activity and components of “natural environments,” such as plants and animals. Industrialization and urbanization make understanding urban ecosystems much more important.

The urban heat island effect makes cities hotter than the surrounding environment. This can cause deaths as well as increases in pollution. Human activities as well as the compact layout of buildings changes the climate. Solutions must involve all of these aspects before any real change can occur.

Because the population is much larger in cities, more pollution occurs in urban areas than in rural ones.  Therefore, it affects the biological processes of inhabitants as well as the composition of cities. There is no way to completely get rid of pollution. As a result, any potential solutions must take that into consideration.

The behavior of water in cities differs from natural bodies of water. Flooding and pollution are common in urban bodies of water. This impacts the health and livelihood of the city’s inhabitants. By understanding the way water behaves in urban settings, people can come up with effective solutions.

Because urban ecosystems are so different from typical understandings of ecosystems, it is important to understand how they operate to prevent harmful effects. Instead of viewing the environment as something independent from humans, we need to look at both of these things as parts of a whole. They work together and affect each other. Only by researching this relationship can we work to benefit both humans and the environment.

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