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Introduction
Concern for the quality of the environment has been evident in the
United States for over 100 years. One result of this concern has been
the passage of laws, regulations, and treaties that require actions to
preserve environmental quality or that inhibit actions detrimental to the
environment. These legislative acts have caused the investment of large
amounts of time, effort, and money in analyses of the possible envi-
ronmental impacts of specific development projects or management
decisions. For two reasons, the effectiveness of these analyses and the
magnitude of resources devoted to them are controversial (Goodman,
1975; Schindler, 1976; Suter, 1981~: available scientific information is
often not used effectively in their preparation, and research conducted
to provide additional information is often inadequate. It is also com-
monly perceived that massive studies yield predictions that are little
better than those produced with much less effort, cost, and time. This
report, by the Committee on Applications of Ecological Theory to En-
vironmental Problems, in the Board on Basic Biology of the National
Research Council's Commission on Life Sciences, deals with both prob-
lems. It explores how the scientific tools of ecology can be used more
effectively in dealing with a variety of environmental problems.
"Ecological theory," as described in standard textbooks on ecology,
is seldom applied directly to environmental problems. But ecological
"knowledge" including not only theory, but also facts, observations,
research results, syntheses, models, and methods of investigation has
been extremely important in developing approaches to a wide range of
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2
INTRODUCTION
environmental problems. This report discusses knowledge that has proved
useful and how it has been used. It deals with a wide range of envi-
ronmental issues, including prediction and management of environ-
mental impacts, management of renewable resources, protection and
restoration of species and ecosystems, control of agricultural and sil-
vicultural pests, and use of generic ecological studies to promote un-
derstanding of classes of environmental problems. Rather than focusing
on what is wrong with the way ecology is often applied, we use suc-
cessful applications to show how ecological knowledge can be valuable
when used appropriately.
Environmental assessment and management are based on societal goals,
which are not always clearly articulated. The social effects of environ-
mental changes and the way goals are developed by society are important
aspects of environmental problems. Nevertheless, we treat only the bio-
logical side of environmental problems, to avoid taking on an unman-
ageably large task.
The report does not attempt to cover all aspects of ecology. To have
done so would have made our task unacceptably difficult and the report
unacceptably long. We have focused on different kinds of ecological
knowledge and appropriate arenas for their use, but have restricted the
coverage of subjects and have not provided details of methods, except as
examples or in the case studies.
The subjects covered were determined by the experiences of the com-
mittee members. Ecological subjects that have interfaces with chemistry,
geology, and hydrology have been slighted, except in some of the case
studies (e.g., Chapters 20, 21, 23, and 241. Thus, detailed discussions of
such subjects as CO2 buildup, acid deposition, ecotoxicology, and the
effects of complex chemical mixtures in the environment are lacking. For
treatment of these important topics, the reader is referred to several recent
reviews (e.g., Harshbarger and Black, in press; Maki etal., 1980; National
Research Council, 1976, 1981, 1982, 1983a,b,c, 1984, in press a,b; Reif,
1984).
Among the most important methods some of which have changed the
scope and scale of ecological research that do not receive explicit treat-
ment in this report are equations for estimating environmental partitioning
of chemicals and related phenomena, such as transformations and trans-
port; hazard evaluation protocols and risk assessment; validation; decision
analysis; remote sensing; interpretation of photographs and satellite pho-
tography; and bioassays. Some methods such as modeling, statistical
analysis, and use of computers-are not discussed specifically, but appear
in many of the chapters of Part I and the case studies.
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INTRODUCTION
Structure
3
STRUCTURE AND AUDIENCE OF THE REPORT
The report is divided into "What we know" (Part I) and "How our
knowledge is applied" (Part II). Chapters 1-5 treat a number of categories
of ecological knowledge and Chapters 6-10 discuss procedures and kinds
of knowledge that are common to most environmental problems. Part II
presents studies of 13 specific cases of environmental problem-solving.
The first three chapters deal with populations of single species, inter-
actions between two species, and community ecology. They focus on the
kinds of information that are available and how that information might be
useful in solving environmental problems. Chapter 4 discusses the flow
of energy and materials through ecosystems; Chapter 5 deals with the
effects of changes in time and space scales on ecological processes and
products. Chapter 6 explores the benefits of treating environmental ma-
nipulations as large-scale experiments so that we can learn more from
them. Chapters 7 and 8 discuss biological monitoring and the management
of ecological systems in the face of the substantial uncertainty associated
with the behavior of those systems.
Chapter 9 deals with cumulative environmental changes that result from
repeated perturbations. There is increasing recognition that some of our
most severe environmental problems involve the cumulative effects of
many small local actions individually insignificant, but collectively cre-
ating major regional and even global changes. The discussion points out
the major issues associated with cumulative effects, which have only
recently begun to receive serious consideration, but which present some
of the most difficult challenges to decision-makers.
Chapter 10 deals with procedures for application of ecological knowl-
edge. It begins with a discussion of how ecology can help in concep-
tualizing a problem and in devising appropriate approaches to its solution.
We focus on the design of ecological studies for predicting and managing
the effects of manipulations, emphasizing the importance of monitoring
projects and decisions to determine their consequences.
Part II discusses 13 cases chosen as instructive examples of the appli-
cation of ecological knowledge to various kinds of problems. The cases
were selected because the committee members and consultants who were
asked for suggestions were familiar with them and believed that they would
reveal the challenges of applying ecological knowledge, show the diffi-
culty of predicting accurately the behavior of complex systems, and point
out the substantial value of monitoring the results of manipulations. The
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4
INTRODUCTION
cases were chosen to exemplify scientifically sound uses of ecological
knowledge. No attempt was made to achieve comprehensive coverage; of
necessity, the cases are a small sample of a large universe of potentially
informative examples.
Audience
This report is intended for a broad audience, including:
· Those who prepare, receive, and use environmental evaluations and
management plans.
· Legislators and regulators concerned with environmental issues.
· Teachers and students in the natural and environmental sciences.
TYPES OF ECOLOGICAL KNOWLEDGE
The chapters in Part I discuss the ways in which ecological knowledge
has been applied in a variety of environmental problems, from the man-
agement of renewable resources to the prediction of environmental im-
pacts. A few common themes run through these chapters. The themes are
related to the basic characteristics of ecological systems that are of fun-
damental importance to understanding their responses to perturbations.
Complex Linkages
Because of the complex linkages between species in ecosystems, the
effects of changes are often indirect. Obvious and direct influences on the
objects of study are sometimes not as important as less obvious indirect
influences. Problem-solvers can find it helpful to develop diagrams that
show both direct and indirect influences and show the pathways through
which indirect agents exert their influences (Andrewartha and Birch, 1984~.
Such diagrams are accounting schemes that help to identify important
environmental factors. The case studies in Part II contain many examples
of indirect effects, such as the effect of DDT on birds far from sites of
its application (Chapter 24) and the mobilization of mercury that results
from changing the level of a lake (Chapter 211. These phenomena could
not have been predicted by analyses that concentrated on direct effects.
In addition, many ecological interactions are characterized by strong non-
linear effects brought about by slight changes in key factors.
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INTRODUCTION
Density Dependence
Because environments are finite and resources might not be renewed
as quickly as they are harvested, the success of individuals often depends
on the number of individuals of the same and other species in their en-
vironments. Often, but not always, conditions deteriorate for individuals
as the numbers of individuals of the same species, predators, and parasites
increase. Conversely, conditions can improve when the numbers of in-
dividuals of those classes decrease. It is therefore often possible to extract
much higher sustainable yields from populations than would be expected
on the basis of an examination of birth, growth, and death rates in an
unharvested population existing close to the limit set by environmental
resources. Alternatively, high population densities in most areas could
prevent individuals displaced by a perturbation from moving into other
areas. Very low densities might influence the probability of finding mates,
erode genetic diversity of a population, and increase the probability of its
extinction. The existence of density-dependent effects does not necessarily
imply that populations exist at steady densities. These effects can cause
populations to fluctuate regularly or irregularly (May 1973), as did the
blowflies studied by Nicholson and Bailey (1935) and the bean weevil
Callosubrochus chinensis studied by Utida (1957~. Moreover, density-
independent effects can often mask density-dependent ones, because they
are often much larger.
The Uniqueness of individuals
Each individual in a sexually reproducing population is unique, as
opposed to many nonliving entities (e.g., all CO2 molecules can be treated
as identical). A species is composed of different age and sex classes, and
genetic variation occurs within each class. Plants with open growth systems
often have substantial intraindividual variability that is important for con-
sumers of the plants (Whitham et al., 19841. Because of genetic variability,
management practices can create selective pressures that cause genetic
and thus phenotypic changes in a population that sometimes subvert the
goals of the management practices (Chapter 11.
Keystone Species
Keystone species are those which exert influences over other members
of their ecological communities out of proportion to their abundances.
Keystone species can have various roles in ecological communities. For
example, dominant plants are the major photosynthesizers in communities,
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6
INTRODUCTION
and they also form the physical structure in which many interactions in
the system take place. Keystone predators preferentially eat prey that
would be competitive dominants in the absence of predation. As a result,
keystone predators create conditions favorable for the existence of species
that are crowded out of systems with less predation. Keystone predators
have been most commonly identified among predators on sessile prey-
such as plants and sessile marine invertebrates of rocky shores-that
compete for space (Harper, 1969; Hurlbert and Mulla, 1981; Lubchenco,
1978; Morin, 1983; Paine, 1974; Paine and Vadas, 19691. Keystone mu-
tualists are essential for survival of other members of their communities,
even though the amount of resources they consume is sometimes small.
Well-known examples are pollinators and frugivores, ants that patrol and
protect plants, and microorganisms associated with vascular plants (Alex-
ander, 1971; Gilbert, 1975; Howe, 1981; Janzen, 1966~. Because changes
in the populations of keystone species can influence community dynamics
in major ways, astute environmental problem-solvers are alert to keystone
relationships in the communities being altered (Chapter 3~.
Biological Magnification'
Organisms are united through food chains, so materials taken up by
prey can accumulate and become concentrated in their predators. Passage
of substances through several trophic levels in a community can result in
concentrations hundreds of times those initially present in the environment.
The greatly magnified indirect effects of pesticides like DDT, which are
metabolically stable and fat-soluble, constitute a striking case of biological
magnification (Chapter 244.
Population Fragmentation
Human activities often change large patches of, say, forest or prairie
into small patches surrounded by land devoted to other purposes (such as
agriculture, forest plantations, highways, and cities). Fragmentation of
habitats sets in motion processes that can cause unexpected changes in
the system. Among these processes is the loss of species unable to exist
in small patches (Chapter 51. An important management implication is
the need to provide corridors of suitable habitat through which individuals
can travel between more extensive patches of appropriate habitat. Ignoring
the larger, heterogeneous environment in which local populations of in-
terest are set can lead to poor management of those populations (Chapters
17 and 194.
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INTRODUCTION
7
Stability Boundaries
"Stability," the tendency of ecological systems to remain in a relatively
constant state, can result from several processes (Orians, 19751. Of con-
cern to the manager and environmental problem-solver are the resistance
of a system or a component of it to change, the speed with which it returns
to its previous state when the perturbation ends, and its stability bound-
aries the range over which it can be changed without leaving it unable
to return to its previous state (Holling, 19731. The crossing of stability
boundaries or thresholds by individual organisms can lead to large changes
in their functioning. Photoperiods above a threshold might be necessary
to induce a plant to flower or an animal to come into breeding condition
(e.g., Farner, 1964; Salisbury and Ross, 1978; Sundararaj and Vasali,
19764. A critical minimal density of prey might be necessary for a par-
ticular kind of predator to survive in an area. A specific patch size of
suitable habitat might be necessary for a particular species to survive
(Chapter 171. An organism might be able to withstand temperatures down
to or up to a critical point, but not beyond.
Stability boundaries are also important for more complex ecological
systems. For example, environmental change and overharvesting can cause
persistent changes in the composition of fish stocks (Dean, 1980; Gulland
and Garcia, 1984; Chapters 1 and 81. Overgrazed plant communities might
be resistant to invasion by new species, even if grazing ceases. These
"alternate stable states" are usually less desirable from the human per-
spective, but some are seen as beneficial, as when a shrub stage resistant
to invasion by trees is established as a low-maintenance community along
roads and powerline rights of way (Niering and Egler, 19551. Managing
systems to achieve greater constancy, a common human objective, can
reduce their ability to withstand perturbations. For example, the suppres-
sion of spruce budworrn populations in eastern Canada through the use
of insecticides achieved the intended preservation of the pulp and paper
industry in the short run, but left the forests and the economy more
vulnerable to outbreaks of a size and intensity that would be impossible
in undisturbed forests (Holling, 19731.
It is especially important for the environmental problem-solver to rec-
ognize that these thresholds are sometimes not apparent until after they
have been crossed. An important role of ecological knowledge is to suggest
what such thresholds are likely to be.
Aggregate Variables
Ecologists and other scientists use aggregate variables in several ways.
Typically, entities are grouped on the basis of shared characteristics. These
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8
lNrRODUCTlON
might be traits shared because of common ancestry, such as the dorsal,
hollow nervous system of all vertebrates; they might result from inde-
pendent adaptations, as in the aggregate entity "herbivores." Ecological
guilds groups of species that use common resources in similar ways-
are examples of aggregates consisting of units connected by strong inter-
actions. Aggregates can also be based on some composite process or
product, such as productivity or biomass, that is deemed to be of theoretical
or applied interest.
Analysis of complex systems requires the use of aggregate variables.
Aggregate variables should be designed to capture the essence of traits or
processes. It is the nature of aggregate variables that they lose substantial
amounts of information; but essential information should not be sacrificed.
A major challenge in using ecological information to help in solving
environmental problems is to delineate aggregrate variables, their prop-
erties, and what will be gained and lost if they are adopted.
Complexity and Uncertainty
Ecological theory is most fully developed for relatively simple systems,
which have relatively small numbers of interacting units. Ecology's great-
est predictive success occurs in cases that involve only one or two species.
That is why, for example, management of game and fish populations
through regulation of hunting and fishing is often successful. Predicting
the outcome of interactions among many species is much more difficult.
Therefore, most environmental problem-solving entails considerable un-
certainty. Wise problem-solvers learn to expect the unexpected and to
develop approaches that allow them to learn as they proceed, altering their
responses as they learn more about the system and avoiding irrevocable
actions (Chapter 8~.
Scales in Space and Time
Processes and products in ecological systems are strongly influenced
by differences in scale (Addicott, 1978; Andrewartha and Birch, 1954,
1984; Levin, 1974; Wiens, 1976; Chapter 5~. Large lakes are not simply
smaller lakes made bigger, and a large expanse of forest is not the same
as a collection of small woodlots. Patchy environments have more edges
in proportion to their area than do homogeneous environments; they create
dispersal problems for organisms inhabiting them, and they lead to high
local extinction rates. Speciation, particularly of large organisms, requires
large expanses of suitable habitat (Soule and Wilcox, 1980) larger, in
fact, than most parks and reserves. Success in achieving some local goal
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INTRODUCTION
9
can set in motion processes that cause regional results opposite to those
desired (Chapter 191. Populations of some species are maintained by high
rates of reproduction in a small fraction of the area that they occupy;
populations in the rest of the area depend on a steady supply of immigrants
from sites with high reproductive rates. Evolutionary changes can cause
both interacting organisms and the results of their interactions to change,
often rapidly enough to be important for the environmental problem-solver
(Chapter 1~.
APPLICATIONS OF ECOLOGICAL KNOWLEDGE
The chapters of Part I are organized in part by their ecological content.
Chapters 1-5 deal with a variety of kinds of ecological knowledge, many
having specific applicability to different kinds of problem-solving. Chap-
ters 6-10 deal with knowledge and procedures that are more general in
their applicability. We briefly summarize here the parts of the report that
deal with particular kinds of application (see Table 1) so that users can
more easily tap the sources of knowledge most important to them.
Renewable-Resource Management
Renewable-resource management refers to commercial and recreational
harvesting of animals and plants. The important topics of population growth,
life histories, habitat selection and other behaviors, genetics of popula-
tions, and evolution in response to management are dealt with in Chapter
1. Equally important for managers are interactions between populations
(Chapter 2) and energetics i.e., productivity and nutrient requirements
(Chapter 41. Examples of renewable-resource management are discussed
TABLE 1 Kinds of Applications of Ecological Knowledge and Where
They Are Discussed
Application
Renewable-resource management
Conservation of species
Control of pests and diseases
Impact assessment and prediction of effects
Preservation of communities
Preservation of habitat
Contaminants and toxic substances
Mitigation of effects of construction
Restoration
General applications
Chapter
1,2,4, 12, 19
1-3, 5, 8, 17
1-3, 13-15, 24
6-9, 16, 21-24
3-5,8, 18,20
7-9, 17, 18,20,23
4, 7, 9, 20-22, 24
7, 10, 16, 18, 21
3-5,8, 18
6-10
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10
INTRODUCTION
in detail in Chapter 12 (managing a fishery) and Chapter 19 (managing a
forest).
Conservation of Species
Closely related to the commercial and recreational harvest of plants and
animals is the protection of species that lack commercial value, but that
have aesthetic value or that play important roles in ecosystems valued for
other reasons. Species conservation requires knowledge of the ecology of
the species (Chapter I), its interactions with other species (Chapter 2),
and its relationships to its ecological community (Chapter 31. The size
and shape of the available habitat and the population size of the species
needed to ensure its survival for acceptably long periods are central to
management decisions (Chapter 5), as is knowledge of environmental and
demographic variability (Chapter 81. Application of such knowledge to
the conservation of populations of spotted owls is discussed in Chapter
17.
Control of Pests and Diseases
The control of pests and diseases usually requires knowledge of the
natural history and population characteristics of the pests and their victims
(Chapter 1) and understanding of their interactions (Chapter 2) and of the
ecological communities in which they occur (Chapter 31. Attempts to
control pests and diseases often result in the evolution of resistance, which
tends to reduce the effectiveness of the programs (Chapter 11. Cases of
control are discussed in Chapter 13 (vampire bats), Chapter 14 (biological
control of citrus pests), Chapter 15 (malaria vectors), and Chapter 24
(results of attempts to control insects with DDT).
Impact Assessment and Prediction of Effects
Predicting effects and assessing potential impacts of activities require
knowledge of present conditions (Chapter 7) and of the variability inherent
in nature and the uncertainties of science (Chapter 81; without such knowl-
edge, effects cannot be reliably detected and the causes of change cannot
be understood. Because the effects of a project can combine with effects
of other projects elsewhere, and the effects of distant projects can add to
the effects of the project under consideration, potential cumulative effects
might require modifications in project design (Chapter 91. It is often useful
to compare the situation under consideration with similar ones elsewhere
and to carry out pilot studies (Chapter 61. Cases of impact assessment are
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INTRODUCTION
discussed in Chapter 16 (predicting the effects of construction on a herd
of caribou), Chapter 21 (predicting the effects of freshwater impound-
ment), Chapter 22 (studies of the effects of ionizing radiation), Chapter
23 (studies of the effects of clearcutting), and Chapter 24 (predicting and
learning the effects of the use of DDT and application of that knowledge
to other cases).
11
Preservation of Communities
When the management goal is the preservation of entire communities
of organisms, an understanding of community ecology (Chapter 3), of
productivity and nutrient cycling (Chapter 4), and of the required space
and time scales (Chapter 5) is important. Natural variability in climate
and community patterns will also affect preservation efforts (Chapter 81.
Chapter 18 (restoration of communities of plants on derelict lands) and
Chapter 20 (protecting a lake ecosystem from the effects of eutrophication)
discuss examples of such applications.
Preservation of Habitat
The conservation of communities and species requires preservation of
the habitat in which those organisms live. Monitoring both before and
after efforts are initiated is necessary to determine the success of the efforts
(Chapter 71. The variability of natural systems and the cumulative effects
of various activities, often far from the site of concern, can strongly
influence the outcome of preservation attempts (Chapters 8 and 9~. Some
aspects of habitat preservation are treated in Chapters 17, 18, 20, and 23.
Contaminants and Toxic Substances
The pervasive and crucial issues of pollution and exposure to toxic
chemicals are relatively neglected in this report, but the transport of chem-
icals is discussed in Chapter 4, indicator species and biological monitoring
to detect pollutants and toxic chemicals are discussed in Chapter 7, and
the problem of cumulative effects (e.g., several sources of pollutants) is
discussed in Chapter 9. Specific examples are presented in Chapter 20
(excess nutrients), Chapter 21 (chemistry and hydrology related to heavy
metals), Chapter 22 (ionizing radiation), and Chapter 24 (persistent pes-
ticides).
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12
INTRODUCTION
Mitigation of Effects of Construction
Mitigation of undesired side effects of projects is often economically,
aesthetically, or legally motivated. If done after the project is completed,
it might take the form of restoration (see below); but the best approach
to mitigation is to make it unnecessary by appropriate design of the project.
This requires careful planning and scoping (Chapter 10), as well as careful
monitoring (Chapter 71. Chapter 16 (protecting caribou during hydro-
electric development) and Chapter 21 (raising the water level of a lake)
provide examples of including mitigation efforts in the design of a project;
Chapter 18 (restoration of derelict land) describes mitigation of effects of
projects completed many years earlier.
Restoration
To restore an ecosystem, one must have a goal to work toward. This
requires some knowledge of previous conditions. Success in reaching the
goal depends on knowledge of community structure (Chapter 3), of pro-
ductivity and nutrient requirements (Chapter 4), of the space and time
scales that will be needed for success (Chapter 5), and of natural variation
in biotic and abiotic factors (Chapter 81. Chapter 18 describes the resto-
ration of plant communities on derelict lands in Britain.
General Applications
Some issues, procedures, and kinds of knowledge common to most
environmental problems are treated in Chapters 6-10. There is always
uncertainty, both in the abiotic environment and in organisms' responses
to perturbations (Chapter 8~. And there is always a need for rigorous
scientific procedures and careful scoping, even when time and money are
short (Chapter 10~. It is always helpful to compare the case at issue with
similar ones; it is often useful to conduct pilot experiments, if feasible
(Chapter 64. Potential cumulative effects are often a concern, and moni-
toring is almost always necessary to ascertain current conditions, to detect
variability, and to measure the effects of actions (Chapter 71.
THE CASE STUDIES
The objective of Part II is to show how ecological knowledge has been
used in planning and carrying out problem-solving efforts, including how
the knowledge has been limited and how it has had to be adapted to the
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INTRODUCTION
13
details of specific problems. The case studies are referred to repeatedly
in Part I.
The existence and application of scientific knowledge do not guarantee
correct predictions. Ecological systems are complex, situations are often
unique, and predictive ecological theories are sometimes inadequate.
Nonetheless, when scientific predictions turn out to be inaccurate, the
results can reveal important aspects of the limitations of even the best
available scientific approaches and show the need to increase the knowl-
edge base on which decision-makers depend.
We selected examples to cover a wide array of types of environmental
problem-solving (Table 21. In some of our cases such as those of the
North Pacific halibut, the spotted owl, and the Newfoundland caribou-
protection of a single species or achievement of a sustained harvest was
the goal. In the malaria, red scale, and vampire bat cases, the goal was
to eliminate an organism or at least to reduce it enough to render the
damage it caused acceptable. Problem-solving oriented toward manipu-
lating a single species can draw on general ecological knowledge, such
as population dynamics and predator-prey theory, and on the results of
previous efforts. As the case studies show, proper targeting of management
usually requires a great deal of knowledge about the natural history of the
organisms in question.
Other case studies deal with problem-solving at the community level.
The objective might have been the achievement of a sustained steady yield
of useful products from a combination of species, as in the New Brunswick
forest case, or the creation of a functioning ecological community similar
to one that existed before the influence of human disturbance, as in the
Lake Washington and derelict lands cases. In some cases, the purpose
was to anticipate, and thereby to reduce, the undesirable impacts of a
future project. For example, in the Southern Indian Lake case, the lake
was altered for hydroelectric power generation, in the hope that it would
not impair other uses of the lake.
Still other case studies deal with projects in which the objective was to
determine the impacts of practices that take place in many locations over
a broad area. Some of these practices are subject to legal regulation (use
of pesticides, forestry practices, and uses of nuclear energy), and case
studies can help to determine what kinds of legal restraints might be
properly applied to reduce unwanted consequences in natural environ-
ments. As examples we have chosen the use of DDT in the United States,
forest clearcutting, and the effects of nuclear radiation on ecological com-
munities. In the latter two, a major objective was scientific.
To ensure consistent emphasis of particular points, we adopted a general
format for the presentation of case studies. The preparer of each case
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14
TABLE 2 Synopsis of Case Studies Presented in Part II
INTRODUCTION
Short Title Type of Case Subject
Halibut
(Chapter 12)
Vampire Bat
(Chapter 13)
Red Scale
(Chapter 14)
Malaria
(Chapter 15)
Caribou
(Chapter 16)
Spotted Owl
(Chapter 17)
Derelict Lands
(Chapter 18)
New Brunswick Forest
(Chapter 19)
Renewable-resource manage-
ment
Pest control
Pest control
Disease control
Impact assessment
Species conservation
Ecosystem restoration
Renewable-resource manage-
ment
Lake Washington Ecosystem protection
(Chapter 20)
Southern Indian Lake
(Chapter 21)
Managing an international
marine fishery
Chemical control of a para-
site on cattle in Central
America
Biological control of a pest
on citrus crops in Califor-
nia
Experimental study of chem-
ical control of a malaria
vector
Protecting a caribou herd
during hydroelectric de-
velopment
Managing a regional popula
tion of a rare species
Restoring seminatural plant
communities in mined
areas
Developing a model for
Impact assessment
long-term regional forestry
management
Predicting and controlling
cumulative impacts of
sewage effluent in an ur-
ban lake
Predicting impacts of raising
the level of a subarctic
lake
Nuclear Radiation Generic ecological studies Ecological effects of nuclear
(Chapter 22) radiation
Forest Clearcutting Generic ecological studies Ecological effects of clear
(Chapter 23) cutting forests
DDT Pesticide use Ecological effects of DDT
(Chapter 24)
study, whether a committee member or another person intimately involved
with the project, was asked to treat in sequence, if possible, the history
of the study project, the major environmental problems that it posed, the
types of ecological knowledge used in the project, and the role of the
knowledge in determining how the problems were perceived, approached,
and dealt with. Each case study is followed by a committee comment on
the project's strengths and weaknesses and on the lessons that can be
drawn from it for other studies of a similar nature. Our concentration on
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INTRODUCTION
15
ecological knowledge is not meant to suggest that other sources of knowl-
edge were not used or were necessarily less important in dealing with the
environmental problems posed; it merely reflects our specific objective of
showing how ecological knowledge can be used creatively in helping to
solve environmental problems.
RECOMMENDATIONS
This report does not attempt to provide a "cookbook" for solving
environmental problems; that would be impractical. Rather, it is a guide
to the process of "cooking," indicating where useful approaches to par-
ticular problems can be found in the literature and suggesting how ap-
propriate knowledge and skills might be integrated for dealing with complex
environmental problems.
The following recommendations constitute general advice to field work-
ers, managers, and regulators and are intended to form the basis of sci-
entifically sound but flexible environmental problem-solving. The overall
approach we recommend is described in Chapter 10. Here we highlight
some major recommendations that apply to most environmental problems.
If followed, they should increase the probability that solutions chosen for
dealing with environmental problems are imaginative and appropriate.
More details can be found in the chapters referred to, including the case
studies, which constitute recommendations by example.
· Involve scientists from the beginning. Scientists should be involved
from the beginning of a project in setting goals, in identifying valued
ecosystem components, and in scoping the problem (Chapter 101. Sci-
entists do not determine the values attached by society to ecosystem com-
ponents, but they might know which organisms have important roles in
the ecosystem that are not understood or appreciated by the general public.
Scientists can help to assemble information about a project site and about
similar sites and projects elsewhere. They are also helpful in defining
goals, because of their knowledge of potential outcomes of manipulations
that might be considered. They can advise on the implications of trying
to achieve particular goals, on the measurement of values, and on why
seemingly compatible values might conflict. The involvement of scientists
does not guarantee success, but it should increase the probability that
project plans are appropriate.
· Treat projects as experiments. Many projects are carried out on a
larger scale than scientific experiments can be. To learn the scientific and
management lessons that these projects have to offer, we need to treat
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16
INTRODUCTION
them as experiments (Chapter 61. Treating projects as environmental ex-
periments increases the understanding of basic ecological science and
allows the testing of predictions made in impact statements. Careful mon-
itoring is essential to anyone who would understand the effects of projects
(Chapter 7), test the predictions made in impact statements (Chapter 6),
detect changes in baseline conditions (Chapter 8), and detect cumulative
effects (Chapter 9~. To be most successful, monitoring should be incor-
porated into the project and study plans (Chapters 7 and 101.
· Publish information. Many people associated with projects learn a
great deal from them, but without making their knowledge available to
others through publication. If the knowledge were made widely available,
similar projects could be managed better and could serve as controls. The
cases described in Chapters 12, 14, 15, 18-20, 22, and 23 are good
examples.
· Set proper boundaries on projects. Setting appropriate boundaries
(Chapters 5 and 9) involves matching the scale of management to the
scales of ecosystems. Environmental problems that cross political bound-
aries are especially difficult to deal with (e.g., Chapters 12 and 23), so
the appropriate jurisdiction for management should be chosen carefully
(Chapter 91.
· Use natural-history information. Carefully collected natural-history
information can help in solving environmental problems (Chapter 1~. The
success of the cases described in Chapters 12-21 depended on such in-
formation; for example, the control of such pests as vampire bats (Chapter
13) and red scale (Chapter 15) was based on identifying key natural-
history features of the focal organisms.
· Be aware of interactions. Interactions among populations and among
species in communities are complex (Chapters 2-4), and they can influence
the effects of perturbations. It is important to remember that the most
obvious connections are not necessarily the most important.
· Be alert for possible cumulative elects. Small perturbations, even if
individually trivial, can have important cumulative effects when they are
repeated in space and time. Therefore, many projects need to be evaluated
not only in isolation, but also in the context of the overall frequency of
their occurrence. Similarly, when a particular environment is being stud-
ied, investigators need to be alert for possible effects of activities and
perturbations elsewhere (Chapter 91.
· Plan for heterogeneity in space and time. Environmental patchiness,
variation in time, and variation in the species composition of ecological
communities conspire to complicate environmental management (Chapter
51. These considerations are particularly important in harvesting popula-
tions (for example, the maximal sustainable yield changes as the envi
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INTRODUCTION
17
ronment changes) and in conservation. Interpopulation variations both
genetic and behavioral, can also complicate management, because of rapid
evolutionary changes (e.g., Chapters 1 and 151.
· Prepare for uncertainty and think probabilistically. A goal of man-
agement is usually to minimize uncertainty. But uncertainty is unavoidable
(Chapter 8), and managers are advised to expect it and to plan for it. In
addition, pretending that uncertainty is absent leads to bad planning and
inflexibility. Therefore, both scientists and managers must be willing to
think in terms of probabilities and to deal with them, as weather forecasters
and farmers, sailors, fliers, and the general public do every day.
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Representative terms from entire chapter:
cumulative effects
