Natural Cities: Urban Ecology and the Restoration of Urban Ecosystems
By Charles P. Lord, Eric Strauss, and Aaron Toffler
INTRODUCTION
The relatively young science of ecology attempts to forge a holistic understanding of the natural processes that take place within a defined system. The central idea is that a patch of the planet, a natural community, contains discrete living (biotic) and nonliving (abiotic) elements that interact in synergistic ways. These elements include the living organisms, the landscape patches, the parent geologic materials underlying the soils, and the local hydrologic and weather patterns. These patterns of interactions can be categorized and compared between and among various ecosystems. Energy flow (metabolism), food webs, predator-prey interactions, and co-evolution are typical categories of investigation common to all ecosystems. The scale of an ecosystem varies with the question being asked. Understanding the ecology of the Charles River in Massachusetts, for instance, requires that the patch include at least twenty-six towns and cities. On the other hand, studies of the ecology of an endangered amphibian, such as the spadefoot toad, may be focused on a single vernal pool and its surrounding upland habitat.
Ecologists have been comfortable for over a century with the notion of natural ecosystems such as deserts, tundra, grasslands, old growth forests, and estuarine salt marshes. Even animal societies such as honeybee colonies, termite mounds, and wolf packs are routinely considered as ecological units.2 However, the concept of the natural city, a human city functioning as an ecosystem on the scale of an estuary or a rain forest, is in its academic infancy.
Traditionally, the study of ecology has been applied to natural systems in such a way that the variable of human impact has been excluded from the biological equation. Our understanding of ecology and its younger sibling science, biodiversity, has been developed by sending researchers into pristine ecosystems in order to gather data on the intricate co-evolved relationships among organisms. Ecologists have focused on the interactions within the natural community. The new biodiversity scientists have tried to identify as many species as possible and use those data to forge an understanding of species distribution and abundance. In addition to providing lucent images of nature, these studies have provided the infrastructure for the disciplines of biogeography (the mapping of species), behavioral ecology (the behavior of individuals and groups), and most recently, conservation biology (protecting those species from extinction). With the exception of those researchers interfacing with public health, however, the studies have been conducted in remote areas where the human footprint was as small as possible. Those public health scientists who did work in cities were conducting research on the negative impacts of urban living and essentially trying to stamp out any remaining plant or animal populations that were deemed troublesome. Cities were not viewed as natural entities but as foreign impositions upon the native landscape.
The pervading perspective from the academic research centers was that true ecological research was possible only when one reached the wilderness. There, the footprint of human activity was small and had not yet destroyed the elements of a natural balance. The foundation of this approach to ecology traces its roots back to the transcendental writers of the late 19th century, such as Thoreau and Emerson. These writers desired to escape the artificial environment of the city and therefore wrote from solitary retreats where they encountered nature firsthand. The 20th century gave rise to many influential ecological pioneers who shared this perspective, such as John Muir, Rachel Carson, and Aldo Leopold. In fact, Leopold's account of the natural history of his beloved Wisconsin wilderness in A Sand County Almanac served as a manifesto to a generation of field biologists.
While such an approach to ecological studies provides beautiful and robust models of nature, this approach is often inapplicable to some of the most imposing challenges in human ecology, particularly those involving the management of our urban ecosystems. Nearly half of the world's population lives in cities, many in mega-cities that harbor 10 million residents or more (e.g. Mexico City, with more than 17 million people). In the United States, nearly three-quarters of the population lives in urban centers, and that trend is increasing. The declining state, but increasing size and environmental importance of urban ecosystems provide enormous opportunity for the application of ecological thinking and research. The heavy social burden of the injustices born of the urban environment demands that scientific talent be employed in the service of urban management. The ecological models developed in the remote beauty of national parks and wildlife refuges need to be tested and modified in order to provide guidance to those professionals struggling to solve problems and manage dwindling resources within the city landscape. The city as an ecosystem is a radical idea that challenges traditional scientists to think and behave in new ways. There are indications that this urban perspective is grinding up and replacing some of the ecological dogma that currently exists.
A revolution in science viewed in real time, however, is like watching the tide come in. Usually, the events are slow to unfold, and we need a marker from which to gauge the change. One notable indication that urban ecology has begun to achieve recognition as a legitimate science is the funding of two major projects by the National Science Foundation (NSF) that seek to reveal the ecological*321 machinery of cities. Baltimore and Phoenix are urban research sites in the U.S. Long Term Ecological Research Network (LTER), a system of 1100 scientists working at twenty-four distinct sites across the world. Begun in 1980, the LTER program has attempted to research “ecological processes over long temporal and broad spatial scales” in order to identify and solve ecological problems. The philosophy of the program has tilted towards the applied aspects of ecology, but the study sites have ranged from the polar ice of Antarctica to the rainforests of Puerto Rico. The inclusion of two urban ecosystems in this network represents a sea change in the discipline of ecology and a recognition of the importance of understanding the ecology of our cities.
The development of ecological thinking about cities will have a broad and profound impact on all the issues of social importance to urban stakeholders. Public health, resource allocation, water quality, energy conservation, and historical and natural preservation will benefit from a revisionist approach that includes the biology of the system as the foundation for its understanding and management. The concept of the natural city will have its roots in a series of scientific models that will be testable in a variety of urban environments.
The relatively young science of ecology attempts to forge a holistic understanding of the natural processes that take place within a defined system. The central idea is that a patch of the planet, a natural community, contains discrete living (biotic) and nonliving (abiotic) elements that interact in synergistic ways. These elements include the living organisms, the landscape patches, the parent geologic materials underlying the soils, and the local hydrologic and weather patterns. These patterns of interactions can be categorized and compared between and among various ecosystems. Energy flow (metabolism), food webs, predator-prey interactions, and co-evolution are typical categories of investigation common to all ecosystems. The scale of an ecosystem varies with the question being asked. Understanding the ecology of the Charles River in Massachusetts, for instance, requires that the patch include at least twenty-six towns and cities. On the other hand, studies of the ecology of an endangered amphibian, such as the spadefoot toad, may be focused on a single vernal pool and its surrounding upland habitat.
Ecologists have been comfortable for over a century with the notion of natural ecosystems such as deserts, tundra, grasslands, old growth forests, and estuarine salt marshes. Even animal societies such as honeybee colonies, termite mounds, and wolf packs are routinely considered as ecological units.2 However, the concept of the natural city, a human city functioning as an ecosystem on the scale of an estuary or a rain forest, is in its academic infancy.
Traditionally, the study of ecology has been applied to natural systems in such a way that the variable of human impact has been excluded from the biological equation. Our understanding of ecology and its younger sibling science, biodiversity, has been developed by sending researchers into pristine ecosystems in order to gather data on the intricate co-evolved relationships among organisms. Ecologists have focused on the interactions within the natural community. The new biodiversity scientists have tried to identify as many species as possible and use those data to forge an understanding of species distribution and abundance. In addition to providing lucent images of nature, these studies have provided the infrastructure for the disciplines of biogeography (the mapping of species), behavioral ecology (the behavior of individuals and groups), and most recently, conservation biology (protecting those species from extinction). With the exception of those researchers interfacing with public health, however, the studies have been conducted in remote areas where the human footprint was as small as possible. Those public health scientists who did work in cities were conducting research on the negative impacts of urban living and essentially trying to stamp out any remaining plant or animal populations that were deemed troublesome. Cities were not viewed as natural entities but as foreign impositions upon the native landscape.
The pervading perspective from the academic research centers was that true ecological research was possible only when one reached the wilderness. There, the footprint of human activity was small and had not yet destroyed the elements of a natural balance. The foundation of this approach to ecology traces its roots back to the transcendental writers of the late 19th century, such as Thoreau and Emerson. These writers desired to escape the artificial environment of the city and therefore wrote from solitary retreats where they encountered nature firsthand. The 20th century gave rise to many influential ecological pioneers who shared this perspective, such as John Muir, Rachel Carson, and Aldo Leopold. In fact, Leopold's account of the natural history of his beloved Wisconsin wilderness in A Sand County Almanac served as a manifesto to a generation of field biologists.
While such an approach to ecological studies provides beautiful and robust models of nature, this approach is often inapplicable to some of the most imposing challenges in human ecology, particularly those involving the management of our urban ecosystems. Nearly half of the world's population lives in cities, many in mega-cities that harbor 10 million residents or more (e.g. Mexico City, with more than 17 million people). In the United States, nearly three-quarters of the population lives in urban centers, and that trend is increasing. The declining state, but increasing size and environmental importance of urban ecosystems provide enormous opportunity for the application of ecological thinking and research. The heavy social burden of the injustices born of the urban environment demands that scientific talent be employed in the service of urban management. The ecological models developed in the remote beauty of national parks and wildlife refuges need to be tested and modified in order to provide guidance to those professionals struggling to solve problems and manage dwindling resources within the city landscape. The city as an ecosystem is a radical idea that challenges traditional scientists to think and behave in new ways. There are indications that this urban perspective is grinding up and replacing some of the ecological dogma that currently exists.
A revolution in science viewed in real time, however, is like watching the tide come in. Usually, the events are slow to unfold, and we need a marker from which to gauge the change. One notable indication that urban ecology has begun to achieve recognition as a legitimate science is the funding of two major projects by the National Science Foundation (NSF) that seek to reveal the ecological*321 machinery of cities. Baltimore and Phoenix are urban research sites in the U.S. Long Term Ecological Research Network (LTER), a system of 1100 scientists working at twenty-four distinct sites across the world. Begun in 1980, the LTER program has attempted to research “ecological processes over long temporal and broad spatial scales” in order to identify and solve ecological problems. The philosophy of the program has tilted towards the applied aspects of ecology, but the study sites have ranged from the polar ice of Antarctica to the rainforests of Puerto Rico. The inclusion of two urban ecosystems in this network represents a sea change in the discipline of ecology and a recognition of the importance of understanding the ecology of our cities.
The development of ecological thinking about cities will have a broad and profound impact on all the issues of social importance to urban stakeholders. Public health, resource allocation, water quality, energy conservation, and historical and natural preservation will benefit from a revisionist approach that includes the biology of the system as the foundation for its understanding and management. The concept of the natural city will have its roots in a series of scientific models that will be testable in a variety of urban environments.