1.3 Basic Ecological Principles and Their Relation to Ecological Assessments
17
5. Holistic, comprehensive, and transdisciplinary
considerations.
6. Delineation (definition) of the ecosystem naturally, for example, bioregionally instead of arbitrarily.
7. Consideration of different levels or scales of
system structure, process, and function.
8. Description of system dynamics through ecological concepts such as stability and feedback.
9. Use of anticipatory, flexible research, and
planning processes.
10. Consideration of ethics of quality, well-being,
integrity, and resilience.
11. Recognition of systemic limits to action-defining
and seeking sustainability.
Ecological assessments (conducted at national
and regional scales) are essential if resource managers and stakeholders are to describe desired ecological conditions for the nation's major ecosystems and to set the proper ecological context for
lands managed at finer scales (e.g., National
Forests). By providing basic characterizations of
ecosystems, ecological assessments may also help
to identify needs for more specific (and traditional)
issue-driven risk assessments. To meet these objectives, integrated ecological assessments must
answer a number of questions regarding ecosystem
sustainability (Table 1.2).
1.3 Basic Ecological Principles
and Their Relation to
Ecological Assessments
To address questions like those in Table 1.2, highly
diverse data are required, induding vegetation
(plot-based and remotely sensed), maps of biophysical variables (soils, watersheds, landforms,
etc.), and socioeconomic data. For a number of reasons, interpreting such data often proves to be complicated. First, many aspects of ecosystems remain
enigmatic: defining interactions between ecosystem components and distinguishing between cause
and effect relations are difficult tasks; the complexity of ecosystem dynamics is usually unknown;
and the hierarchical arrangement of ecological systems is often poorly known, including scale dependencies of ecological processes and patterns.
Furthermore, time is often limited, both for testing
the hypotheses formulated in the development of
protocols for sampling design and analytical methods and for validating and verifying the models
used in an assessment.
These challenges to ecological assessments have
long been recognized (Lessard et aI., 1999). To develop a comprehensive method for dealing with
these problems, several different conceptual frameworks (Hutchinson, 1953; Forman and Godron,
1986; Urban et aI., 1987; Levin, 1992; Costanza et
al., 1993) must be integrated in the articulation of
basic ecological principles that underlie any ecological assessment effort. In this section, we provide a brief overview of some of the more important ecological principles that need to be considered
in ecological assessments, synthesized from
Lessard et ai. (1999) and Haynes et ai. (1996). The
reader is encouraged to see Chapter 2 for a more
complete discussion of ecological principles.
In any ecological assessment, the following four
ecological principles (Haynes et aI., 1996) should
be considered:
1. Ecosystems are dynamic, evolutionary, and resilient.
2. Ecosystems can be viewed spatially and temporally within organization levels.
3. Ecosystems have biophysical, economic, and
social limits.
4. Ecosystem patterns and processes are not completely predictable.
1.3.1 Ecosystems Are Dynamic,
Evolutionary, and Resilient
Most ecological assessments emphasize the description of static ecosystem patterns, like existing
vegetation; however, assessments of the spatial relations of ecological systems cannot ignore the dynamics of such patterns and the processes that create them. Ecological systems exhibit temporal
changes along various developmental pathways
that result in different types of organization.
Processes that drive these changes are called structuring processes. Many conceptual models used in
ecological assessments assume that all ecosystems
reach an equilibrium or quasi-equilibrium (e.g.,
succession leads to climax). It has long been documented, however, that in reality ecosystems are
rarely in equilibrium. Although it may be convenient for modeling and planning exercises to assume equilibrium at a given scale, it is impossible
to ignore ecological system dynamics that exhibit
multiple successional pathways, discontinuities,
and surprises and that follow constantly changing
environmental conditions (e.g., Holling, 1986;
Kay, 1991; Costanza et aI., 1993). Accordingly,
ecological assessments must consider the complexity of ecosystem dynamics, and analysis pro-
17
5. Holistic, comprehensive, and transdisciplinary
considerations.
6. Delineation (definition) of the ecosystem naturally, for example, bioregionally instead of arbitrarily.
7. Consideration of different levels or scales of
system structure, process, and function.
8. Description of system dynamics through ecological concepts such as stability and feedback.
9. Use of anticipatory, flexible research, and
planning processes.
10. Consideration of ethics of quality, well-being,
integrity, and resilience.
11. Recognition of systemic limits to action-defining
and seeking sustainability.
Ecological assessments (conducted at national
and regional scales) are essential if resource managers and stakeholders are to describe desired ecological conditions for the nation's major ecosystems and to set the proper ecological context for
lands managed at finer scales (e.g., National
Forests). By providing basic characterizations of
ecosystems, ecological assessments may also help
to identify needs for more specific (and traditional)
issue-driven risk assessments. To meet these objectives, integrated ecological assessments must
answer a number of questions regarding ecosystem
sustainability (Table 1.2).
1.3 Basic Ecological Principles
and Their Relation to
Ecological Assessments
To address questions like those in Table 1.2, highly
diverse data are required, induding vegetation
(plot-based and remotely sensed), maps of biophysical variables (soils, watersheds, landforms,
etc.), and socioeconomic data. For a number of reasons, interpreting such data often proves to be complicated. First, many aspects of ecosystems remain
enigmatic: defining interactions between ecosystem components and distinguishing between cause
and effect relations are difficult tasks; the complexity of ecosystem dynamics is usually unknown;
and the hierarchical arrangement of ecological systems is often poorly known, including scale dependencies of ecological processes and patterns.
Furthermore, time is often limited, both for testing
the hypotheses formulated in the development of
protocols for sampling design and analytical methods and for validating and verifying the models
used in an assessment.
These challenges to ecological assessments have
long been recognized (Lessard et aI., 1999). To develop a comprehensive method for dealing with
these problems, several different conceptual frameworks (Hutchinson, 1953; Forman and Godron,
1986; Urban et aI., 1987; Levin, 1992; Costanza et
al., 1993) must be integrated in the articulation of
basic ecological principles that underlie any ecological assessment effort. In this section, we provide a brief overview of some of the more important ecological principles that need to be considered
in ecological assessments, synthesized from
Lessard et ai. (1999) and Haynes et ai. (1996). The
reader is encouraged to see Chapter 2 for a more
complete discussion of ecological principles.
In any ecological assessment, the following four
ecological principles (Haynes et aI., 1996) should
be considered:
1. Ecosystems are dynamic, evolutionary, and resilient.
2. Ecosystems can be viewed spatially and temporally within organization levels.
3. Ecosystems have biophysical, economic, and
social limits.
4. Ecosystem patterns and processes are not completely predictable.
1.3.1 Ecosystems Are Dynamic,
Evolutionary, and Resilient
Most ecological assessments emphasize the description of static ecosystem patterns, like existing
vegetation; however, assessments of the spatial relations of ecological systems cannot ignore the dynamics of such patterns and the processes that create them. Ecological systems exhibit temporal
changes along various developmental pathways
that result in different types of organization.
Processes that drive these changes are called structuring processes. Many conceptual models used in
ecological assessments assume that all ecosystems
reach an equilibrium or quasi-equilibrium (e.g.,
succession leads to climax). It has long been documented, however, that in reality ecosystems are
rarely in equilibrium. Although it may be convenient for modeling and planning exercises to assume equilibrium at a given scale, it is impossible
to ignore ecological system dynamics that exhibit
multiple successional pathways, discontinuities,
and surprises and that follow constantly changing
environmental conditions (e.g., Holling, 1986;
Kay, 1991; Costanza et aI., 1993). Accordingly,
ecological assessments must consider the complexity of ecosystem dynamics, and analysis pro-