Exploring Urban Ecology: Understanding the City as an Ecosystem

Cities are often thought of as places built by humans, for humans – concrete, steel, and asphalt stretching as far as the eye can see. But beneath that surface lies a dynamic, living system. Birds nest on ledges, trees line the streets filtering air, and microorganisms cycle nutrients through urban soils. Urban ecology is the field dedicated to understanding these complex interactions – and it’s reshaping how we think about cities altogether.

What is urban ecology? 🔗

Urban ecology is an interdisciplinary field that studies the relationships between living organisms – including humans – and their environments within cities and urbanizing landscapes. It draws from biology, geography, sociology, urban planning, economics, engineering, and public health to build a comprehensive picture of how cities function as ecosystems.

What makes urban ecology different from traditional ecology is its explicit focus on human-dominated environments. In conventional ecology, researchers typically study forests, wetlands, or grasslands where human influence is minimal. Urban ecology flips this approach. Here, buildings, roads, parks, and other built structures are treated as habitat types that create unique conditions for both native and non-native species. The field recognizes that cities are not biological deserts – they are unique ecosystems with their own energy flows, nutrient cycles, and species interactions.

At its core, urban ecology operates through two conceptual lenses: ecology “in” cities and ecology “of” cities. The first asks how urbanization affects the ecology of living organisms and how ecological processes in cities differ from those in other environments. The second explores the interactions between ecological and social systems within an urban setting. Together, these lenses capture the full scope of what makes urban areas ecologically distinctive.

Why cities qualify as ecosystems 🔗

An ecosystem, at its simplest, is a set of interacting species and their local environment functioning together. Cities meet this definition. Urban ecosystems contain biological components – plants, animals, microorganisms, and human populations – alongside physical components like soil, water, air, climate, and built infrastructure. What distinguishes them from natural ecosystems is the dominant role humans play in shaping these systems.

According to Britannica, the physical complex of urban ecosystems includes buildings, transportation networks, modified surfaces such as parking lots and roofs, and the environmental alterations resulting from human decisions. Energy use, material import and export, and the generation of pollution, waste, and excess heat are all integral to how these systems operate. Urban ecosystems tend to be warmer than surrounding areas, experience less rainwater infiltration into soil, and show higher rates of surface runoff after storms.

Despite these challenges, cities harbour notable biodiversity. Urban parks, gardens, vacant lots, and even rooftops support diverse species assemblages. Research has revealed that cities can function as critical stopover sites for migrating birds and that moderate levels of urbanization can sometimes increase diversity for certain species groups.

Two perspectives: biological-centric vs. human-centric 🔗

Urban ecology can be approached from two primary perspectives, each offering distinct insights into the relationship between nature and cities. Understanding both is essential for grasping the full picture.

The biological-centric perspective 🔗

This approach views urban areas through the lens of traditional ecological principles. Researchers working from this perspective focus on understanding how natural ecological processes – predation, competition, succession, adaptation – operate within urban settings. Humans are acknowledged as one component of the ecosystem, but the primary focus remains on ecological dynamics.

Typical research questions from this angle include how bird migration patterns are disrupted by city lights, how urban heat islands influence plant growth, or how fragmented green spaces affect wildlife movement. Studies might examine urban wildlife corridors, the role of green roofs in supporting pollinator populations, or ecological differences between urban and rural streams.

This perspective is often described as “ecology in cities” – applying established ecological concepts to the urban context.

The human-centric perspective 🔗

The human-centric approach places social systems at the centre of urban ecological analysis. It recognizes that cities are fundamentally shaped by human decisions, and that understanding urban ecology requires deep engagement with social, economic, and cultural factors.

Researchers taking this view might study how socioeconomic status influences the distribution of urban forests, how environmental justice issues shape access to green spaces, or how cultural practices affect neighbourhood-level biodiversity. This perspective is referred to as “ecology of cities” – it treats the entire urban system, including its governance structures and economic forces, as the subject of ecological study.

As scholars at Springer’s Urban Ecosystems journal have noted, defining what “urban” actually means remains a challenge. Simply calling an ecosystem “human-dominated” does not capture the history of development, sphere of influence, and range of impacts that characterize urban environments. A more precise, interdisciplinary definition would help researchers compare findings across different cities and projects.

Toward an integrated view 🔗

Many contemporary researchers argue that neither perspective alone is sufficient. The most productive approach treats humans and nature as interacting forces that jointly shape measurable patterns and processes. In this integrated view, human factors and natural systems – both biotic and abiotic – are coupled together, each driving and being affected by the patterns they create. A 2024 paper published in Ambio described this as a transformative shift from a biologically based discipline toward a transdisciplinary, action-oriented field that works not just to understand cities but to co-produce sustainable solutions with diverse urban actors.

Regional differences: how North America and Europe approach urban ecology 🔗

Urban ecology has developed along different trajectories depending on geographic context. The most notable distinction lies between the North American and European traditions, which have historically emphasized different dimensions of the field.

The European tradition 🔗

European urban ecology has its roots in post-World War II field studies. As Britannica explains, ecologists began conducting comprehensive studies of plants, animals, soils, and environmental conditions in European cities after the war, when many vacant bomb sites provided open study areas. This launched a tradition focused on examining open spaces, volunteer plant communities, and the animal populations associated with them.

Over time, European research placed strong emphasis on the biota of urban areas – cataloguing species, studying vegetation dynamics, and developing ecological planning as a professional discipline aimed at enhancing biological diversity and green space amenities within cities. This tradition maintained close connections with landscape architecture and urban planning, reflecting Europe’s long history of dense urban development and its strong planning culture.

The North American tradition 🔗

The North American approach developed differently. In the early 20th century, sociologists such as Robert E. Park and Ernest Watson Burgess developed a theory of urban ecology that viewed cities as environments governed by principles similar to those in nature. This sociological lens became deeply embedded in North American urban ecology, which has traditionally given greater weight to social sciences, ecosystem fluxes and processes, and human dimensions of urban landscapes.

A major catalyst for North American urban ecology research came in the 1990s, when the U.S. National Science Foundation funded two urban long-term ecological research (LTER) centres – one in Baltimore and one in Phoenix. These centres promoted deeply interdisciplinary approaches, studying not just wildlife and vegetation but also socioeconomic patterns, land-use change, and institutional structures. Key research themes have included urban wildlife management, the ecology of urban forests, and the conservation value of green spaces in major cities like New York, Chicago, and Vancouver.

Latin America and the Global South 🔗

Beyond the North American-European divide, other regional traditions are gaining recognition. The Latin American approach, for instance, tends to focus on the effect of human activity on biodiversity and ecosystem fluxes within urban settings. Meanwhile, researchers in the Global South are highlighting themes largely absent from Northern research – including informality, inequality, urban-rural connections, and the ecological dynamics of small and medium-sized towns where most future urban growth will take place.

A 2024 analysis published in PMC confirmed a significant geographic imbalance in urban ecology research: roughly two-thirds of urban vertebrate studies have been conducted in North America or Europe, while only about 18% came from South America, Asia, or Africa – the very regions projected to experience the greatest urbanization in the coming decades. The good news is that this disparity is slowly narrowing, with studies from the Global South increasing year over year.

The convergence of traditions 🔗

In recent decades, the distinct North American and European approaches have been gradually merging. The complexity of modern urban challenges – from climate adaptation to environmental justice – demands tools and insights from both biological and social sciences. Contemporary urban ecology increasingly treats cities as social-ecological-technological systems (SETS), recognizing that social structures, ecological dynamics, and built infrastructure are all deeply interconnected.

This convergence has also been driven by the growing involvement of disciplines beyond ecology. Urban planning, landscape architecture, engineering, anthropology, and public health all contribute to the modern understanding of how urban ecosystems function. The result is a field that has moved well beyond simply cataloguing urban species – it now aims to actively shape more sustainable, resilient, and equitable cities.

Why urban ecology matters now 🔗

More than half of the world’s population currently lives in urban areas, and that proportion is expected to reach two-thirds within the next few decades. As cities expand and densify, the ecological processes operating within them – from air and water purification to heat regulation and biodiversity support – become critical to human health and well-being.

Urban ecology provides the scientific basis for practical interventions: green infrastructure planning, urban wildlife corridor design, heat island mitigation, stormwater management, and biodiversity conservation. It also raises important questions about who benefits from urban nature and who bears the burdens of environmental degradation – making it inseparable from discussions of environmental justice.

The field continues to evolve. New technologies like remote sensing, environmental sensors, and citizen science platforms are enabling more sophisticated monitoring of urban ecological conditions. At the same time, transdisciplinary collaboration is becoming the norm rather than the exception. Urban ecology is no longer just an academic discipline – it is becoming essential knowledge for designing cities that work for both people and the natural systems they depend on.

What do you think? Does your city or neighbourhood feel like an ecosystem to you – and if so, what ecological relationships do you notice in your daily life? How might understanding your city through an ecological lens change the way you interact with your surroundings?

References

1. https://www.intechopen.com/chapters/45413
2. https://www.britannica.com/science/urban-ecosystem
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC11106554/
4. https://en.wikipedia.org/wiki/Urban_ecology
5. https://link.springer.com/article/10.1023/A:1009540018553
6. https://pubmed.ncbi.nlm.nih.gov/38643343/
7. https://www.ebsco.com/research-starters/environmental-sciences/urban-ecology
8. https://link.springer.com/chapter/10.1007/978-3-030-67650-6_17