It's time to think differently about cities and nature. Understanding how to better connect our cities with the benefits nature provides will be increasingly important as people migrate to cities and flourish in them. All this urban growth, along with challenges of adapting to climate change, will require a new approach to infrastructure if we're going to be successful. Yet guidance on how to plan and implement projects to protect or restore natural infrastructure is often hard to come by. With Conservation for Cities, Robert McDonald offers a comprehensive framework for maintaining and strengthening the supporting bonds between cities and nature through innovative infrastructure projects. After presenting a broad approach to incorporating natural infrastructure priorities into urban planning, he focuses each following chapter on a specific ecosystem service. He describes a wide variety of benefits, and helps practitioners answer fundamental questions: What are the best ecosystem services to enhance in a particular city or neighborhood? How might planners best combine green and grey infrastructure to solve problems facing a city? What are the regulatory and policy tools that can help fund and implement projects? Finally, McDonald explains how to develop a cost-effective mix of grey and green infrastructure and offers targeted advice on quantifying the benefits. Written by one of The Nature Conservancy's lead scientists on cities and natural infrastructure, Conservation for Cities is a book that ecologists, planners, and landscape architects will turn to again and again as they plan and implement a wide variety of projects.
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About the Author
Dr. Robert McDonald is Senior Scientist for Sustainable Land Use at The Nature Conservancy, where he is lead scientist for the organization's efforts to figure out how to make cities more sustainable. He holds a PhD in Ecology from Duke University and has published more than 30 peer-reviewed publications, many of them on the science of how cities impact and depend on the environment. He blogs for The Nature Conservancy'sCool Green Scienceblog and has published two recent essays on urban/environment interactions in a collection calledTaking Sides: Clashing Views in Global Issues(McGraw-Hill) and inThe Chronicle of Higher Education.
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Conservation for Cities
How to Plan and Build Natural Infrastructure
By Robert I. McDonald
ISLAND PRESSCopyright © 2015 Robert I. McDonald
All rights reserved.
Nature in an Urban World
Looking at the skyline, it is hard for me to imagine that just a few decades ago this was a sleepy town by the Fustian River. The skyscrapers of Shenzhen now stretch out to the horizon. Some of the newer towers have a glass façade and fashionable design, but many of the other buildings appear as more or less identical grey concrete blocks, lined up in long rows that shrink toward the horizon. And then everywhere, ubiquitous, are the cranes. The cranes of Shenzhen are always moving, flitting from one building site to another, frantically assembling steel beams into the frames for new skyscrapers. In a few short decades, they have built a city where once there was a small village, and they keep on building. Farmers' fields have disappeared under a forest of skyscrapers, in just one generation. How did this dramatic urban growth happen?
Every city's story, like every individual's life, is unique and full of happenstance. For many decades, the Chinese government under Mao Zedong actively tried to keep cities from growing and in some cases forced urban youth to move to the countryside. With Mao's death and new political leadership, this anti-urban attitude eased a little bit. Shenzhen, then a small town of just 60,000 people (UNPD 2011), was designated one of China's four Special Economic Zones (SEZs), where free market policies and urban development were allowed. All of the suppressed economic development of China began to concentrate in these SEZs.
Shenzhen's location, just across the river from the bustling city of Hong Kong, was perfect. It had a large, deepwater port and, compared with Hong Kong, cheap wages. Manufacturers rapidly set up factories, and during the 1980s the industrial output of the city grew by 60 percent a year (Montgomery et al. 2003). The total population surpassed 10 million in 2010 (UNPD 2011), an astonishing 175-fold increase in its population since becoming an SEZ.
But the dark side of such rapid growth is severe environmental challenges that affect residents' quality of life. Shenzhen's water supply system has struggled to keep pace with its burgeoning population, and providing water of sufficient quality has required significant new infrastructure. Shenzhen's air quality has declined, as industrial production and millions of cars on the road have led to high levels of smog and particulate matter (Che et al. 2011). The rain is so acidic, due to sulfur dioxide and nitrogen oxide from coal-burning power plants, that it sometimes damages the paint on cars. Shenzhen has the distinction of having one of the fastest urban growth rates in the world (UNPD 2011). But while extreme, its story contains themes that are present in many urban areas. Many other cities in both the developing and developed world are experiencing growth (fig. 1.1), and are struggling to accommodate that growth while protecting the environment. All this growth will require new infrastructure, as will the challenge of adapting cities to climate change.
The twenty-first century will be the fastest period of urban growth in human history. In a few decades, more homes will be built than have accumulated over centuries of urban development in Europe. Rapidly urbanizing regions like Asia and Africa will add billions of people to their cities (fig. 1.1). In a sense, Asia and Africa are catching up with Europe and the United States, which already have substantial proportions of their total populations living in cities. Even in developed countries, however, urban population often continues to expand in some urban areas, driven by overall population growth or shifts in population among cities. Older infrastructure in growing cities needs to be refurbished or replaced. Globally, the twenty-first century will require massive urban infrastructure development, in roads and pipes and power lines and schools.
Ecologists, urban planners, economists, and landscape architects are increasingly asked to consider the role that natural infrastructure — the natural habitat or constructed natural spaces that supply crucial benefits to urban residents — can play in meeting these challenges. Whether it is the role of upstream forests in maintaining water quality in reservoirs, how shade trees keep cities cool during heat waves, or the way parks can contribute to the quality of life and financial success of a city, natural infrastructure is all the rage.
Even in Shenzhen, the concept of natural infrastructure has caught on. By 2000, the city's rapid urban growth had made the Fustian River an open sewer. The river had been channelized, with concrete embankments boxing in the its foul waters for most of its length as it passed through the city. In 2009, the Shenzhen Fustian River project began. At a cost of 300 million yuan (US$49 million), the project first created new pipes to carry stormwater and sewage water to a treatment facility, to limit the release of untreated sewage into the Fustian. But this grey infrastructure investment — concrete and pipes and other engineered structures — was complemented by an investment in green infrastructure. The concrete embankments were torn down, replaced by sand and mud and pebbles. Eventually, artificial wetlands were created in low-lying areas of the floodplain, to further filter stormwater as it reached the Fustian, as well as to provide a beautiful park along the river (Lide 2013).
Yet for all the excitement about natural infrastructure, guidance on how to plan and implement projects is often hard to come by. How can a city like Shenzhen tell which of nature's benefits — the ecosystem services provided by natural habitat — are most important? How can they map which patches of natural habitat are most important, and quantify the economic benefits they provide? How could planners in the Shenzhen Water Planning and Design Institute, which ran the Shenzhen Fustian River project, find the optimal mix of natural infrastructure and traditional grey infrastructure to solve problems facing a city? Perhaps most important, what are the regulatory and policy tools that a city like Shenzhen can use to help fund and implement natural infrastructure projects?
Conservation for an Urban World
Cities need nature to survive and thrive. And yet the traditional viewpoint of environmentalists concerned with "nature" has been that cities are the enemy. It is true that as cities have expanded, they have affected a lot of biodiversity. One-third of all imperiled species in the United States are in metropolitan regions (NWF, Smart Growth America, and NatureServe 2005), and globally at least one in ten vertebrates is impacted by urbanization (McDonald, Kareiva, and Forman 2008). Conservation planners, wildlife managers, and other practitioners who focus on protecting biodiversity increasingly have to consider the impact of cities on their work and design strategies that limit the impact of cities on wildlife. I call this important work protecting biodiversity in urban areas conservation in cities (fig. 1.2). Protecting biodiversity in areas of urban growth is a classic topic in the conservation planning literature (e.g., Groves 2003). The general strategy is to keep urban growth out of areas of high biodiversity, and wherever possible to keep houses clustered at high density, to minimize the total area of natural habitat impacted by urban growth. This book discusses biodiversity conservation in urban areas in chapter 12.
I have come to believe that the "black hole" view of many ecologists is myopic, in that it focuses conservationists only on biodiversity protection. Nature needs cities. Cities provide numerous economies of scale, reducing per capita use of some resources. Those interested in promoting resource-use efficiency or the reduction of greenhouse gas emissions will often advocate for an urban form that will maximize the efficiency of the city. I call this important task of making our cities more efficient conservation by cities (fig. 1.2). While this book does not focus on how to plan a city to maximize resource-use efficiency, there are numerous other works in the smart growth literature that provide useful tools to planners and ecologists (e.g., APA 2002).
Cities are centers of activity on the landscape, and there are strong bonds between cities and nature, whether inside the city's walls or far away. More and more, conservation biologists, urban planners, and landscape architects are being asked to craft plans that maintain or strengthen these bonds while also allowing for continued urban growth. As the urban century continues, the maintenance of these bonds will become more crucial, both because more people will depend on them and because rapid urban growth, as in the case of Shenzhen, risks severing them.
This book is meant to be a practical guide to this task, which I call conservation for cities (fig. 1.2). It aims to guide urban planners, landscape architects, and conservation practitioners trying to figure out how to use nature to make the lives of those in cities better. Rather than focusing on how to protect nature from cities, this book is about how to protect nature for cities.
Conservation for cities could include the protection of existing patches of natural habitat, their restoration where degraded, or the creation of entirely novel patches of green infrastructure. These patches can be inside the metropolitan region, like a city's parks or street trees. Or they can be far away, like the watershed upstream of a city's reservoir. Humanity is now planning and building the new cities and neighborhoods of the twenty-first century, and this book is about how to incorporate nature into those plans.
Getting Cities What They Need
The patches of vegetation that provide benefits to those in cities are increasingly called natural infrastructure or green infrastructure. The term originated in the United States as an outgrowth of the greenways movement and at first had a strong focus on preserving biodiversity and the landscape connectivity that allows it to move across the landscape. The term has broadened over time, as an increasing variety of benefits from nature are considered by planners. In particular, green infrastructure most often now refers to constructed wetlands and other man-made spaces that help cities reduce the stormwater going into their stormwater drainage system (see chapter 4). In this book, I use the term natural infrastructure in its broadest possible sense, for any piece of nature that provides important benefits to those in a city. For man-made spaces, such as a constructed wetland, I will use the term green infrastructure to designate that while vegetation is key to this infrastructure functioning, it is an area fundamentally designed by people. Conversely, when I want to specifically refer to natural habitat that serves as natural infrastructure, I will use the term critical natural habitat.
But what does it mean to say that a particular way of supplying a benefit to urbanites is more "natural" than another? The distinction may make intuitive sense when we are talking about remnant patches of natural habitat, but what about environments that are clearly human created, like a row of street trees or a constructed wetland? The Oxford English Dictionary defines nature as "the phenomena of the physical world collectively, including plants, animals, the landscape, and other features and products of the earth, as opposed to humans or human creations" (emphasis mine). Taken too strictly, this definition can imply a fake distinction between cities and nature that isn't there. I find it helpful to think about a gradient of naturalness, from very natural (e.g., a wilderness area) to somewhat natural (e.g, critical natural habitat, their ecosystem processes undoubtedly affected in many ways by nearby urban areas) to a little natural (e.g., green infrastructure such as a constructed wetland) to entirely man- made (a piece of grey infrastructure like an asphalt road). Conservation for cities is about using natural infrastructure, ranging from wilderness areas to green infrastructure, rather than only grey infrastructure.
While sometimes the rhetoric around natural infrastructure may imply differently, the idea of using nature to improve the lives of those in cities is not a new one. More than a century ago, Frederick Law Olmsted tried to use the natural processes of wetlands to guide his design of Boston's Green Necklace series of parks, and the Garden City movement in England tried to bring urbanites in closer contact with nature. Post–World War II, the New Town and the Garden City movements also strove to use nature to better urbanites' lives. In the 1960s, Ian McHarg and others mapped natural areas providing important services and protected them in their plans. More recently, the New Urbanism movement has also paid attention to the role parks and street trees play in a vibrant, walkable city. All of these movements thought about natural infrastructure, although in varying ways and for varying purposes.
Natural resource management has also long focused on at least some of the benefits nature can supply to people, such as timber and opportunities for hunting and fishing. Since the 1970s, with the emergence of conservation planning and landscape ecology as disciplines, a large literature has examined how best to protect habitat to maintain biodiversity. This literature shows it is often best to preserve large tracts of remaining natural habitat as core areas. These ideally would be connected by corridors, sometimes called greenways. Since the 1990s, ecologists have increasingly moved to quantify the other benefits that nature provides to people.
These two strands of thought — one coming from urban planning and the other coming from ecology and conservation biology — have merged. There is increasing recognition of the importance of natural infrastructure to good planning, and an increasing number of tools by ecologists that quantify nature's benefits in either physical or economic terms. While we shouldn't let the rhetoric of natural infrastructure get too out of hand, there is something new here in terms of skill and sophistication. Never before have conservation biologists, urban planners, and landscape architects had so many tools at their disposal to plan how to get cities what they need from the natural world.
What Is an Ecosystem Service?
The central premise of this book is that conservation practitioners, urban planners, and landscape architects can use natural infrastructure to meet some of the needs and desires of those in cities. While the scope of human desires is infinitely variable, and many desires are satisfied entirely with human technology, there are certain things that most urbanites the world over would consider part of the good life that necessarily involve nature. Getting clean water to urban residents depends, in part, on the trees upstream of the reservoir preventing erosion. The air quality of a region depends, in part, on how much canopy cover there is to scrub the atmosphere. Parks and other urban public spaces almost universally contain natural features like vegetation alongside human-created features like playgrounds.
All these things that cities demand from the natural world can be thought of, more positively, as benefits nature provides urban dwellers. Ecologists call these benefits, rather dully, ecosystem services. While the core idea is pretty simple, the term has been defined in slightly different ways over the years. In this book, I will use the definition of Boyd and Banghaf (2006), who define ecosystem services as "the components of nature, directly enjoyed, consumed, or used to yield human well-being."
Excerpted from Conservation for Cities by Robert I. McDonald. Copyright © 2015 Robert I. McDonald. Excerpted by permission of ISLAND PRESS.
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Table of Contents
Acknowledgments Chapter 1. Nature in an Urban World Chapter 2. Figuring Out What Matters Chapter 3. Drinking Water Protection Chapter 4. Stormwater Chapter 5. Floodwater Chapter 6. Coastal Protection Chapter 7. Shade Chapter 8. Air Purification Chapter 9 Aesthetic Value Chapter 10: Recreation and Health Chapter 11: Parks and Mental Health Chapter 12: The Value of Biodiversity in Cities Chapter 13: Putting It All Together References Index