Rehabilitating Damaged Ecosystems

Jr. Cairns, Jr. Cairns

• Verlag: CRC Press
• Jahr: 2017
• ISBN:
  9781351419239
• Auflage: 2
• Thema: Tecnologia e ingegneria
• Thema: Gestione ambientale

Built on a strong foundation in restoration ecology, this unique handbook provides practitioners, academics, and managers with vital tools needed to plan for ecosystem conservation, to restore degraded ecosystems, to make cost-effective restoration decisions, and to understand important legal issues. Rehabilitation of Damaged Ecosystems, Second Edition boasts three completely new chapters and five major chapter revisions. Coastal wetlands restoration, watershed rehabilitation and management, mined land reclamation, revegetation of disturbed ecosystems, and river and stream restoration are only a few of the critical topics explored in this timely reference handbook.
This Second Edition provides valuable, reliable data as well as practical methods and techniques for the ongoing fight to protect natural resources and restore damaged ecosystems.

CHAPTER 1

Restoration Ecology: Protecting Our National and Global Life Support Systems

John Cairns, Jr.

CONTENTS

I. Introduction

II. Defining Ecological Restoration

III. Restoring Aquatic Ecosystems

IV. Rehabilitation/ Restoration

V. Documenting Success of Ecological Restoration Projects

VI. Paying for Restoration

VII. Habitat Restoration May Result in Biological Restoration

VIII. Conclusions

References

I. Introduction

Two factors will markedly affect the future of human society: (1) the burgeoning human population presently increasing at nearly 100 million per year and (2) the unprecedented rate of ecological destruction by a single species, Homo sapiens. Society has three choices in its relationship with global ecosystems: (1) continue the present rate of destruction until the inevitable collapse occurs, (2) establish a no-net-ecosystem-loss policy so that each ecosystem degraded or destroyed accidentally or deliberately is replaced in kind, and (3) use the no-net-loss policy as an interim phase and establish a policy that the rate of ecosystem repair exceeds the rate of destruction so that per capita ecosystem services will not diminish precipitously as the global human population grows to 10 billion in the next century. If the human population continues to grow at its present rate, ecologically repaired ecosystems will probably not survive because of the pressures of the increased human population on natural systems. Even so, even temporary repair would improve things for the present inhabitants of the planet. However, if the goal is to have the largest number of people on earth possible for many centuries into the future (that is, to look at the number of humans possible not only at the present moment but possible over a long period of time), then both stabilizing the human population or reducing it gradually with a concomitant strategy for ecological restoration and diminished ecological destruction make sense. The spotted owl controversy has exacerbated the polarization between those who wish to protect the environment and those who wish to protect jobs. This and many other similar controversies have produced some bumper stickers in such poor taste that it is a service not to repeat them. Regrettably, ecological restoration and environmental protection are inseparable because restoration will be less necessary if the rate of destruction is markedly altered, and restoration itself, however well funded, will be only temporary if environmental protection is inadequate. The root of the problem seems to be that some segments of human society are sufficiently environmentally illiterate to believe that humans can exist in totally artificial technological life support systems on this and other planets, with a few selected domesticated species from Earth. Ecologists have not been notably helpful in correcting this misapprehension because their ecosystems of choice for research are generally far from anthropogenic effects or where anthropogenic effects are carefully controlled, such as the Galapagos Islands. Before the era of acid rain, a thinning ozone layer, and atmospheric transport of toxicants, the term “pristine ecosystems” would have been used to describe these areas; however, it now seems unlikely that any area of Earth is unaffected by the activities of human society. In this case, ecologists who think they are studying ecosystems unstressed by anthropogenic effects are either deluded or are basing judgments on inadequate information. There is a regrettable tendency to characterize environmentalists as anti-people/anti-jobs. Persons who favor jobs are labeled self-serving, insensitive slobs who would destroy nature for material gain. This polarization, with regard to environmental or ecological decisions, cannot continue in human society, despite the efforts of many politicians and other interest groups to polarize these issues. None but the most extreme environmentalists wish people to be without jobs or unable to feed their families; and, all but the most far out “jobs first” people wish their children and grandchildren to enjoy natural systems.

Individuals should be able to favor environmental protection and restoration without being callous to the needs of the average citizen for a paying job and financial security. Similarly, those preoccupied with earning a living should not be viewed as anti-environmental, although regular attempts are made by both groups to demonize persons who describe themselves as environmentalists or those who describe themselves as industrialists. Actually, most individuals in both groups are probably interested in the amenities and security which accompany a position with adequate financial rewards and simultaneously wish a good environment in which to spend their leisure time. The term “environmentalist” should not denote someone who puts other organisms ahead of humans, and those wishing the members of human society to enjoy good health and diet should not be viewed automatically as against natural systems. Quinn¹ feels that the word “environment” or “environmentalist” should not be used because of the connotations just described.

Cairns et al.¹ have developed a suite of indicators to monitor regional ecosystem health, similar in concept to management use of “leading economic indicators.” One of the major thrusts in this approach is the high probability that desirable properties of indicators of environmental health vary with their specific management use. Different indicators are required when collecting data to assess the adequacy of the environment, monitor trends over time, provide early warning of environmental degradation, or diagnose the cause of an existing problem. Trade offs between desirable characteristics, costs, and the quality of information are inevitable when choosing indicators for management use. Decisions about what information to collect for which purpose can be made more rationally when available indicators are characterized and matched to management goals. If one finds these assumptions palatable, then it is not particularly profitable to attempt to find a single, all-purpose indicator or to try to extrapolate from a structural attribute to a functional attribute, but rather to select the suite of attributes and methods necessary for each particular decision.

II. Defining Ecological Restoration

Since Rehabilitating Damaged Ecosystems² was first published, much has happened in the field of restoration ecology. Events such as the Exxon Valdez oil spill in Prince William Sound, AL, have called attention to both the need for restoration and the uncertainties about both natural recovery and human assisted recovery. The symposium on biodiversity,³ jointly sponsored by the National Academy of Sciences and the Smithsonian Institution, documented the dramatic global loss of species and the habitat necessary for their continued existence. Cairns⁴ indicated in that volume that ecological restoration, together with preservation of remaining habitat, would be a means of arresting this frightening rate of species extinction. Additionally, the term “ecosystem services” — that is, the activities of ecosystems that benefit humans, such as regulating atmospheric gas balance, improving water quality, providing genetic material for developing new crops in a period of global climate change, developing pest resistance, and the like — is receiving increasing attention. A more detailed description of ecosystem services has been beautifully furnished by Ehrlich and Ehrlich,⁵ and readers are referred to that book for a fuller understanding of this vital point. Again, the rapidly developing field of restoration ecology has the potential, if vigorously utilized, of maintaining these ecosystem services.

Ecosystem services may well be the most persuasive justification to the general public for ecological restoration. The importance of the ecological life support system is now becoming more and more apparent, although almost certainly at too slow a rate. The basic assumption, however (namely, that natural systems can provide services less expensively and more reliably than technological systems), is finally reaching the consciousness of the general public and even some of the world’s leaders. Created wetlands have now been shown in many instances to be far less costly and as, or more, efficient than technological systems for treating a variety of wastes of anthropogenic origin. It is difficult to visualize a technological system that would regulate the atmospheric gas balance as effectively, inexpensively, and reliably as natural ecosystems. There is an inextricable link between human population growth, ecosystem services, and ecological restoration. Global human society has five options with regard to these crucial relationships.

1. Continue the present rate of ecological destruction and human population growth until some catastrophic event causes a re-examination of present policies — The joint statement by the Officers of the Royal Society of London and the U.S. National Academy of Sciences⁶ Population Growth, Resource Consumption, and a Sustainable World is not sanguine about control of human population growth in the near future. They feel the rapid rise from 5.4 billion in 1991 to 10 billion in 2050 may be unavoidable. If the present rate of ecological destruction continues with no significant counteracting ecological restoration, ecosystem services per capita will dramatically, and possibly irreversibly, decline. Although the field of restoration ecology is in its infancy, there is already abundant evidence that the rate of ecological restoration and recovery lags far behind the rate of human population increase. To continue on the present course does not seem prudent.

2. Replace damaged ecosystems with fully functional restored ecosystems at a rate resulting in no-net-loss of ecosystem services — i.e., rate of destruction offset by rate of repair — This would still result in a reduction in ecosystem services per capita if, as seems highly probable, the world’s population continues to expand dramatically. There are other serious problems as well. The relationship between global biodiversity and ecosystem services is not well understood. However, a growing body of evidence indicates that organisms placed in loosely defined functional groups do not, in fact, function similarly (e.g., Nelson Hairston, Jr., Douglas Distinguished Lecture at Rocky Mountain Biological Laboratory, 1992). The no-net-loss approach, however, would provide more time to generate the needed scientific information before funding for large-scale restoration is made available. It is, however, worth emphasizing that robust information on these complex issues will not be generated quickly.

3. Restoring damaged ecosystems at a rate that will produce a net gain of ecosystem services globally — This would still not increase human services per capita in the face of a dramatic increase in human population, but the loss of ecosystem services per capita would be substantively lower than in relationships 1 and 2.

4. Control human population growth to match the rate of ecological restoration so that ecosystem services per capita remain constant — This would, of course, require draconian measures in human society globally. At the present time, such attitudinal changes seem highly improbable but so, a few years back, did the events that have occurred in what was formerly the USSR and the eastern block of communist countries. Even this monumental effort might not dramatically alter the ecosystem services per capita from their present level. However, attitude changes would buy more time for a number of restoration efforts to provide useful scientific information and, at the same time, since human population cannot continue to grow at its present rate forever, provide some evidence of paths toward stabilization of human population least disruptive to human society.

5. Gradually reduce human population size, reduce the rate of ecological destruction, and increase the rate of ecological healing so that sustained long-term use is enhanced — This would, of course, require even more draconian measures. However, if the total number of humans the earth is capable of supporting is to be maximized, the length of time that this is possible should be a major factor. Therefore, reducing human population numbers in the short term will probably increase the total number of humans inhabiting the earth for the entire existence of the species.

III. Restoring Aquatic Ecosystems

The most important event for me in restoration ecology since the first edition of Rehabilitating Damaged Ecosystems was chairing the National Research Council (NRC; the operating arm of the National Academy of Sciences and the National Academy of Engineering) committee that produced Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy.⁸ The definition of “restoration” agreed upon by that committee was “the return of an ecosystem to a close approximation of its condition prior to disturbance.”⁹ This definition, although prepared for aquatic ecosystems, applies equally well to other types of ecosystems. The committee agreed that it would be extraordinarily difficult to restore ecosystems to their precise predisturbance condition since:

1. Each ecosystem is the result of a sequence of climatic, biological, and other events unlikely to be repeated in precisely the same way
2. Commonly, the structural and functional attributes of the ecosystem before disturbance are not precisely documented
3. The species that once inhabited the ecosystem may no longer be available or, if available from other ecosystems, may not be physiologically identical with the race, subspecies, etc. formerly inhabiting the damaged ecosystem

The NRC publication⁸ espouses viewing all restoration in...