Design for Human Ecosystems

Landscape, Land Use, and Natural Resources

John Lyle

• Publisher: Island Press
• Year: 2013
• Print ISBN: 9781559637206
• eBook ISBN: 9781610912600
• Subtopic: Stadtplanung & Landschaftsgestaltung

For more than 30 years, John Tillman Lyle (1934-1998) was one of the leading thinkers in the field of ecological design. Design for Human Ecosystems, originally published in 1985, is his classic text that explores methods of designing landscapes that function in the sustainable ways of natural ecosystems. The book provides a framework for thinking about and understanding ecological design, along with a wealth of real-world examples that bring to life Lyle's key ideas.

Lyle traces the historical growth of design approaches involving natural processes, and presents an introduction to the principles, methods, and techniques that can be used to shape landscape, land use, and natural resources in an ecologically sensitive and sustainable manner. Lyle argues that careful design of human ecosystems recognizes three fundamental concerns: scale (the relative size of the landscape and its connections with larger and smaller systems), the design process itself, and the underlying order that binds ecosystems together and makes them work. He discusses the importance of each of these concerns, and presents a workable approach to designing systems that effectively accounts for all of them. The theory presented is supported throughout by numerous case studies that illustrate its practical applications.

This new edition features a foreword by Joan Woodward, noted landscape architecture professor and colleague of Lyle, that places the book in the context of current ecological design thinking and discusses Lyle's contributions to the field. It will be a valuable resource for landscape architects, planners, students of ecological design, and anyone interested in creating landscapes that meet the needs of all an area's inhabitants -- human and nonhuman alike.

CHAPTER 1

Introduction

Where Mind and Nature Meet

Every piece of land on earth has a history that goes back some four and a half billion years, and each individual history has had its ups and downs. Read the story in the rocks, and you will find periods of relative stability featuring cycles of bloom and decay, of dormancy, birth, death, and rebirth. Some of these periods are long and some short, but none lasts forever. Breaking and dividing these more or less stable periods are occasional upheavals of sudden change. Over the past twelve thousand or so years, ever since the development of agriculture, and especially during the two centuries since the industrial period began, the upheavals have mostly been brought about by human beings themselves. Our restless passion for change has combined with our technical prowess to alter much of the world’s landscape.

Until the middle years of the twentieth century, most people seem to have believed this change was all to the good—a perhaps erratic, but on the whole steady, improvement in the human condition. Since then, the notion of inevitable progress has been called into serious question. Ecologist Ramon Margalef’s chilling assertion that “. . . the evolution of man has not been in the direction of passive adjustment to more mature ecosystems but is actually sustained through a regression of the rest of the biosphere” gives one pause.¹

Nevertheless, there are exceptions. Either by accident or design, human beings have sometimes created landscapes that are at least as rich and as stable, occasionally as beautiful, as those shaped by nature. Consider the rolling farmlands of Northern Europe or the spectacular terraced slopes in the Andes where the Incas maintained a stable agriculture for several hundred years.

Or consider an extraordinary marsh at the northern end of the Salton Sea. The sea itself was created by the accidental flooding of an irrigation canal in 1905 and is now a thoroughly established part of California’s Mojave Desert. The marsh, which is kept wet by runoff water from upstream agricultural irrigation, supports a large and strangely diverse community of birds that has become a subject of intensive study. With the varying salinity levels brought about by the very salty Salton Sea and the relatively fresh runoff water, both fresh- and salt-water birds live there, at least for short periods of time. During the spring and fall migrating seasons, the marsh reminds one of a busy international airport, with all sorts of birds landing and taking off almost continuously, and tens of thousands of others resting on the surface.

This odd, anomalous, incredibly diverse ecosystem would not have existed at all had it not been for the agricultural development of the surrounding lands. If human beings had not settled there and dug their irrigation canals, the whole valley would still be a desert. It is certainly true, as I will argue later on, that desert landscapes have a beauty and a value of their own, and without a doubt, this is a variable, vulnerable, unstable marsh. But if we measure a landscape by its richness and diversity or by the number of creatures it supports, then human beings have certainly made a contribution to nature here, however inadvertent. They have also contributed to their own well-being, of course, since this is among the world’s most productive agricultural regions, even if the farmland may be hardly more stable than the marsh.

If we can create such a rich landscape accidentally, then it seems reasonable to believe that we can do at least as well intentionally, and with proper design make one that is far more sustainable. The science of ecology has given us the information and concepts to work with, even if the precise scientific data that we would like to have in specific cases are usually lacking. By following its principles, even without a great deal of exact data, it is entirely possible to create rich, diverse, productive landscapes that will serve the purposes of both people and nature.

We can best illustrate this point and the underlying principles by exploring a single example in some detail. We will dwell at length on the intricacies of this example because they will serve as an introduction to the concepts and techniques explained in later chapters. Both ecological and social processes stand out sharp and clear in this lucid, relatively simple environment on the southern California coast. The setting is another marsh, but this time a marsh created by nature and degraded by man. In such a place, the time has come for design to eliminate accidents.

AN ARCHETYPE: SAN ELIJO LAGOON

San Elijo Lagoon is a narrow tangle of marshes, mudflats, and shallow channels that push out of the Pacific Ocean into the rolling coastal plain of Southern California, some twenty miles north of San Diego. It is a quiet landscape. Even with development closing in—dikes like long worms dividing its waters, a sewage treatment plant rusting away on an island at one end, a scattering of houses along one edge, a freeway vaulting over—San Elijo still has that sense of airy tranquility that one associates with lagoons everywhere. With rolling hills in the background, it is gentle, unassuming, hardly beautiful, certainly not dramatic. One would not expect it to become a center of conflict.

That is exactly what it was, however, for a number of years. Developers and environmentalists battled over it in what has now become the classic fashion. To understand the conflict, and its eventual resolution, one needs to know something about the lagoon’s history.

For 10,000 years or so before urban civilization arrived here, the tides rolled in and out twice each day, mixing with the fresh water that flowed down from the foothills during the winter rainy season. A prolific community of marshgrasses, molluscs, fish of various types and sizes, an array of shorebirds and waterfowl, and a few small mammals thrived in and around the moving waters. For several hundred years, a tribe of Indians also lived on the edge of the lagoon and shared in the bounty, especially the easily harvested shellfish, which helped assure them a leisurely existence.

All this began to change in 1884 when the Santa Fe Railroad line was built along the coast over the lagoon inlet. Though the trestle allowed water to flow beneath it, the inlet could no longer migrate freely in response to the movement of the ocean waves as it had under natural conditions. Thus, when the waves pressed for an inlet location other than that under the trestle, they failed. As a result sand built up in the channel, shutting off the flow of ocean water for part of the year and isolating the waters of the lagoon. Salinity levels rose in the trapped water, and the materials washing into the lagoon began to collect there. The problems were compounded when a coastal highway was built alongside the railroad a few years later, further restricting the movement of water.

With these two handy transportation links giving easy access to the cities of San Diego to the south and Los Angeles about a hundred miles to the north, people began settling on the surrounding coastal plain. Within just a few years the population built up to such a level that a sewage treatment plan was needed. What better place for it than at the edge of the useless lagoon with its murky water and smelly mudflats? The plant was built without further ado on a small island next to the railroad, and large rectangular sections of the lagoon were divided off with dikes to serve as oxidation ponds. These became geometric splotches of pale green as algae fed by the nutrients in the sewage grew at far too fast a pace and decayed on their surfaces.

For several years following, the deterioration continued to be steady but without the drama of sudden change. Then, following World War II, rows of neatly spaced small houses appeared on one of the slopes adjoining the lagoon. Runoff from the newly urbanized area, increased by lawn irrigation and laden with eroded soil, fertilizer, pesticides, and various kinds of debris, collected on the still waters. By the early 1960s, San Elijo was an eyesore and a health hazard. Only small patches of the marshgrasses remained. Though there were few, if any, fish in the water, a good number of migrating birds still stopped to rest and stalk and flutter about on the mudflats, searching for worms as they followed the sun along the Pacific flyway.

Then, in the mid-1960s, a land developer proposed to make the lagoon useful according to his own lights, and profitable as well, by transforming the wetlands into a marina housing development. He bought about half of the wetlands, including the areas nearest the ocean, and worked out a scheme that called for dredging a broad main channel to connect with the ocean and several fairly straight narrower channels reaching out from it to either side. The dredged material would be used to create fingers of land for residential development between the channels. Each finger would have a street down its center and rows of 40-foot-wide lots on either side. Each lot would have one edge fronting on a channel, where a boat could be kept.

Shortly after that, another developer proposed a similar plan for the eastern half of the lagoon, and proposals soon followed for subdividing the still undeveloped portions of the sloping lands overlooking it for single-family tracts.

Awareness and Conflict

This was the time when environmental activists were beginning to awaken and make a stir. Several groups banded together to do battle with the developers, and the fate of the lagoon became a hot political issue. Environmentalists, whose main interest was the fate of the bird population, wanted the lagoon left alone. Developers, arguing private property rights and tax base and housing needs, not to mention profits, stood firm. Zoning happened to be on their side, most of the wetlands being zoned R-1. It was a classic developer/environmentalist conflict. With the issue in a stalemate, the Environmental Development Agency of San Diego County asked our Laboratory for Experimental Design to study the problems at hand and recommend land planning policies and guidelines for San Elijo and several other coastal lagoons where similar conflicts were emerging.

After grappling with these issues for some time, it became clear to us that they could not be settled simply by pronouncing in favor of preservation or development. In the light of an analysis of the processes involved, political as well as ecological, the proposals of both sides were seriously flawed. If the lagoon were either developed as a marina subdivision or left entirely alone, it would become an environmental liability, and more and more so as time went on. Either way, its rich potential for contributing to the sustenance and amenity of the human community, as well as its pivotal role in natural systems, would be lost.

If the marina plan were to be carried out, concrete bulkheads would have to be built along the edges of the channels to hold the land in place and provide water deep enough for large boats. The result would be no tidal flats at the water’s edge and therefore no marshgrasses. If there are no recurrent marshgrasses to die and decay, there will be no detritus for the shellfish and other small organisms to eat. The energy subsidy that tidal action provides by spreading the detritus around the lagoon to these stationary creatures will thus have gone for naught because there will then be nothing for the small fish and birds to eat, and no small fish for larger fish and birds to eat. Ocean fish will no longer swim into the lagoon to spawn, and it will eventually become a lifeless body of water. The causal chain of unhealthy effects goes on and on.

Somewhat less expected are the consequences of leaving the lagoon alone. Increasing urbanization along the lagoon’s upper drainage basin will bring about an inevitable increase in the siltation rate. Silts could be deposited as much as 100 times faster than they would if the lagoon remained in its preurbanization state. It is the common fate of a lagoon, whether people settle around it or not, to be filled with silt and become first a marsh and finally dry land. If human beings had not come on the scene, this process in the San Elijo Lagoon would probably have occurred only over the next 10,000 to 20,000 years. In its present state and at the present rate of urbanization, the process would probably take 20 to 25 years, and then there would be no place left for the fish and birds anyway. The message is clear. The changes brought about by urbanization are so strong and pervasive that no system within the sphere of urban influence can retain the same character that it would have had if human beings were not present at all.

The fatal, all too common flaw in both the marina housing plan and the hands-off approach is that each focuses on a single purpose. Such a narrow focus leads to an overriding concern with just one aspect of a complex system. This means that other aspects are ignored, and the design process becomes overly simplified. The resulting environment, if realized, will also be very simple, eliminating most of the interactions that might otherwise exist, and along with them, a great many benefits.

It is important to recognize that when we make a plan for a piece of land, or even when we alter it in seemingly minor ways—like landscaping a backyard, for example—we are designing an ecosystem. We are laying the ground in which a network of interactions will take place, interactions that will carry on into the future, evolving according to a pattern that is at least partially predictable. A very simple, single-purpose ecosystem will inevitably fail to provide for many diverse, potentially beneficial roles. At the same time, it will lack the stability needed to resist sudden turbulent changes brought about by external events. Houses built on fingers of filled land may be suddenly inundated by a tidal wave or shaken to pieces by surges in the soft fill material beneath them brought about by an earthquake.

Single-purpose systems also tend to deteriorate from the moment of their realization; their attempts to diversify over time as natural systems do conflicts, of course, with their singular purpose. Maintenan...

Table of contents

• Title Page
• About Island Press
• Copyright Page
• Table of Contents
• FOREWORD
• PREFACE
• CHAPTER 1 - Introduction
• PART I: - Scales of Concern
• PART II: - Design Processes and Methods
• PART III: - Modes of Ecological Order
• REFERENCES
• INDEX