Urban Ecology

Humans have become an urban species, but this is a rather recent phenomena. The first cities appeared around six thousand years ago and while their number increased, their population remained relatively small. This changed in the industrial revolution and today cities are home to more than 50 percent of the world’s human population. Considering that most people live in cities and that ecology has been around for more than one hundred years, it seems obvious to have a subdiscipline called urban ecology. Not until the 1960s and 1970s, however, did urban ecology fully emerge and not until the 1990s did it become wildly popular. Most ecologists shunned urban areas, which have traditionally been viewed in opposition to natural, pristine, and wilderness places. It is true enough that water, air, and soil in cities are often polluted, open spaces are scarce and heavily managed, and communities resemble a wild mix of native and non-native species. It took a while until ecologists perceived this not just as a mess, but also as a research opportunity for understanding key ecological principles. Such principles are treated in separate Oxford Bibliographies in Ecology articles “Competition and Coexistence in Animal Communities,” “Metapopulations and Spatial Population Processes,” “Island Biogeography Theory,” “Succession,” and “Invasive Species.” The study of these phenomena is often referred to as ecology in cities. In the 1970s, a broader, interdisciplinary perspective took hold. It is often referred to as ecology of cities and understands urban areas as social-ecological systems. This shift in perspective stemmed from a recognition that people are influencing ecosystems everywhere on earth. In fact, cities are at the heart of many environmental problems and, therefore, they are a good place to look for solutions. Today, urban ecology is a key discipline for an urban planet. The need to adapt cities to climate change, maintain vegetation in the face of climate extremes, balance the need for development with the need for green space, or decrease the negative local-to-global environmental impacts of cities can be achieved without the interdisciplinary perspective urban ecology provides. This article gives an overview of the ever-increasing urban ecology literature. Of course, the list is subjective, reflecting our academic background, professional network, and research interest as well as our language skills. We acknowledge that we may have ignored important publications, published perhaps in a language we cannot read, or we may have focused too much on one topic and too little on another. We ask readers to understand these limitations and we encourage them to help us improve this article in the future.