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Part One
HUMANS, NATURE, AND INTERACTIONS
All organisms live in ecological communities just as all people live in human communities. Often, however, we tend to forget that human communities also exist within an ecological contextāthat we cannot survive without the natural world around us. In this first part of the book, we consider some of the ties between humans and the ecological settings in which they live. We also begin to explore how humans can manipulate these ties for better and for worse.
Chapter 1 discusses what nature can do for us if we carefully plan interactions between human and ecological communities, as well as what nature can do to us if we are not careful. We also emphasize the importance of context and the need to think beyond the boundaries of official planning domains to create ecologically based plans and designs.
In Chapter 2, we introduce the Earthās living components, collectively known as biodiversity. Biodiversity is the focus of ecologists who try to understand how organisms interact with one another and their physical environment, and of conservationists as they determine how best to protect biodiversity. We explore different reasons why planners, designers, developers, and citizens may want to protect biodiversity as well as the reasons that the native biodiversity of a region is especially valuable.
Humans have significant impacts on the environments in which they liveāimpacts that, over time, can lead to the rise and fall of entire civilizations. Chapter 3 discusses different types of human impacts and lays the groundwork for thinking about how we can lessen these impacts, which is the focus of Part 3 of this book.
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1
Humans Plan
āA man, a plan, a canal, Panama.ā
Palindrome describing the creation of the Panama Canal
āI returned, and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favor to men of skill; but time and chance happeneth to them all.ā
Ecclesiastes 9:11, King James Bible
Over the past few millennia, humans have spread to cover the globe. In the process, we have changed more of the earth, more profoundly, than any species before us. We have altered the face of the planet by building a canal between the Atlantic and Pacific oceans, reestablishing a connection that had not existed for more than 2 million years; by cutting vast forests at all latitudes; and by changing the global climate. As human communities grow, we shape nature. With our advanced technologies, however, we often forget that nature shapes us as well.
As we extend ourselves across the landscape, we plan. Sometimes our plans are explicit and carefully thought out documents, while other times they are implicit thoughts, such as, āIf I create a farm here, it will be productive for several years,ā or āIf we build a town here, it will be a safe place to live.ā Plans give us a secure feeling about the future and reinforce our sense that we can control the landscapes where we live. Drawings and carefully crafted words describe what a given site or region will look like if the plan goes into effectābut these plans can be misleading in two ways.
First, most plans focus primarily on the site or area for which they are planning. While they may consider roads and other aspects of human society outside the study area, they rarely consider ecological issues beyond the boundaries. A certain piece of terrain is either in the study area (and included in the plan) or out of the study area (and typically ignored). In fact, most plans show virtually nothing that is outside the planning area or site, as if it were an island floating in space (see Figure 1-1).
Figure 1-1. This sample site map shows a fifty-acre (20 ha) farm, including fields, farm buildings, a stream and wetlands, and some forest. Like many maps and plans, however, this one shows none of the context surrounding the farm.
Second, the planning and design process is often built on the assumption that human beings fully control the future of the study area. A carefully produced plan is a prediction that verges on being a contract: the plan tells residents of an area what their subdivision or community will become if the plan is followed. As a result, plans typically depict only one or, at most, a handful of future states. The science of ecology, on the other hand, recognizes that ātime and chance happeneth to them all.ā Yes, we can plan and predict, but despite the seeming solidity of our plansā words and images, we cannot guarantee what the future of a site holds. The world of nature is full of chance events, and the mere passage of time brings its own changes as well.
The following two case studies explore the relationship between planningāa wholly human enterpriseāand the workings of nature. As these examples illustrate, planners, designers, and developers would do well to consider the effects of time, chance ecological events, and ecological processes occurring beyond their planning area. By taking these factors into account, we can develop plans that reap major benefits and avoid major problems. By ignoring these factors, we run the risk of costly or tragic consequences as nature runs its course.
New York Cityās Water
Beginning in the mid-nineteenth century, New York City developed one of the best municipal water supplies in the world in terms of quality, reliability, and innovative management.1 Every day, the cityās water system supplies 9 million people with 1.3 billion gallons of potable water.2 The water comes from a system of nineteen reservoirs and lakes fed by a 1,969-square-mile (5,099 square km) watershed that extends more than 100 miles (160 km) north of the city. Perhaps most remarkable of all is that the foundations of this system were laid nearly two centuries ago, in 1835.3 Today, almost all of New Yorkās water still comes from upstate watersheds, and the main treatment that it receives is simply chlorination to kill the pathogens that are sometimes present at low levels.
In 1989, the U.S. Environmental Protection Agency (EPA) promulgated the Surface Water Treatment Rules, which grew out of the Safe Drinking Water Act of 1974.4 Under these rules, New York City would have had to begin filtering its entire water supply for the first time. The filtration plants, according to the City, would have cost $6 to $8 billion to build and would have doubled the price of water for city residents. Instead, throughout the early and mid-1990s, the City and the EPA worked out an alternative to filtering the main water supply: the City would protect and improve water quality by helping towns in the watershed upgrade their sewage treatment facilities and by protecting thousands of acres of land in critical portions of the watershed. As of this writing, the City has purchased or obtained conservation easements on over 50,000 acres (20,000 ha) of land in the upstate watersheds.5 The City alone has committed over $290 million for the land acquisition program, and city, state, and federal contributions to all facets of the watershed program total $1.4 billion.6
One of the most striking features of the agreement between the EPA and the city is the joint official recognition that nature can perform critical ecosystem services for humans. Instead of insisting on building giant filtration plants, the parties recognized that, through proper management, nature may be able to provide drinking water that is as safe as water provided by purely technological means. In addition to drinking water benefits, this watershed-based approach is helping protect rural landscapes just a couple of hours from New York City. Many farms will remain in business, and people are allowed to hike, fish, and hunt on much of the land that the city purchases.
In the early nineteenth century, the City of New York recognized that its water resources would become limiting, and the municipality looked beyond its borders to create a remarkable water supply system. At the end of the twentieth century, the city again looked beyond its bordersāand beyond the confines of human technologyāto envision a future in which humans protect natural areas in ways that help both humans and countless nonhuman organisms living across the landscape. This example offers the following lessons:
- Sometimes we are better served by letting nature provide necessary services than by using technology to fulfill our needs. When we protect and maintain healthy ecosystems, humans can reap significant health and economic benefits.
- By setting aside parcels of nature for one purposeāin this case, to provide safe drinking waterāboth human and ecological communities may benefit in other ways. The watershed lands protect the rural character of dozens of communities as well as high-quality habitat for the regionās native species.
While looking beyond the boundaries of a site can help identify the benefits and services that nature provides, taking a broad view can also help one avoid some of the problems that nature can bring, as the next case study illustrates.
Fire in Colorado
Several years ago, some friends of ours purchased a house in Pine, Colorado. This small community, nestled beside and within the Pike National Forest, has become a bedroom community for Denver as the capacity of the highways into the city has expanded. The mountain ridges surrounding Pine are covered with maturing pine forests that are not only lovely to look at but also contain a surprisingly intact ecological community that includes black bear, elk, mule deer, coyotes, and even mountain lionsāall less than an hourās drive from Denver. This ecosystem offers aesthetic and recreational amenities that have undoubtedly contributed to Pineās recent popularity among home buyers.
This ecosystem, however, is not entirely benign. Although the setting of our friendsā house appears quite suburban, with several houses visible nearby, mountain lions are enough of a danger that many children do not play outside at dusk or dawn. But the single most notable species in this ecosystem is not one of the large mammal species but rather the Ponderosa pines (Pinus ponderosa) that dominate the landscape. And the single most notable process in the ecosystem is fire.
Left alone, Ponderosa pine forests typically burn lightly and frequently, with ground fires removing underbrush while leaving mature trees intact. However, in areas where fires have long been suppressed and underbrush has been allowed to accumulate, as is the case throughout much of the American West, fires burn heavily. As they engorge themselves on the dense growth left unpruned by the now-disrupted fire regime, they become massive, destructive crown fires capable of killing even the largest trees.
In June 2000, the Hi-Meadow Fire roared through the subdivisions and forests of Pine with impunity. The 10,800-acre (4,400 ha) fire destroyed fifty-eight structures, including several houses that could be seen from our friendsā deck, but firefighters stopped the blaze thirty feet from their house (see Color Plate 1).7 The fires around Pine offer several critical lessons:
- Understand the ecological processes of the place you are planning or designing. Developers creating new subdivisions in Ponderosa pine forests, and local planning commissions that approve these subdivisions, need to understand how the local ecosystems function. The same lesson applies to ecosystems across the continent.
- Context is critically important. What is outside the boundary of a site can add tremendous valueāeconomic, ecological, recreational, or aestheticāto the site, but it can also threaten health, safety, and property.
- Always consider the array of possible futures for the land around a site....
