514
Ecological Assessments and Implementing Ecosystem Management
ficulties involved in characterizing ecological systems to inform management typify a more general
challenge confronting ecological science in the face
of movement to a nonequilibrium or dynamic equilibrium conception of ecological systems (Pickett
et aI., 1992; Fiedler et aI., 1997). It is not enough
simply to describe biophysical characteristics and
patterns. Because ecological systems are inherently
dynamic, characterization must be dynamic as well,
including an understanding of the processes that
create patterns on the land and the spatial and temporal scales at which such processes operate (see
Chapter 1).
If systems are constantly in motion through the
influence of processes such as fire and flooding,
how can an ecological assessment create a portrait
that is helpful both now and in the future? Holling
and Meffe (1996) propose as a golden rule that
"natural resource management should strive to retain critical types and ranges of natural variation in
ecosystems." Historical range of variability is certainly a useful concept for guiding ecological assessments and answering ecosystem management
questions (see Chapter 19). Yet questions remain
as to what a critical type or range of variation is
for a specific system (Holling and Meffe, 1996) and
what factors are most usefully measured to determine historic range of variability in a management
context (Botkin et aI., 1997). Furthermore, applying the concept in some instances is hampered by
lack of data and difficulties in interpreting the historical record (Morgan et al., 1994).
Because ecological systems are dynamic in both
space and time, issues of scale pose a significant
challenge to ecological assessment. Patterns and
processes are manifest at many spatial scales, from
a stand of trees to a watershed to a drainage basin,
and temporal scales may range from a single event
to centuries or more. In the past, many ecologists
were content either to ignore spatial and temporal
heterogeneity altogether or at least to make their
work easier by pretending it did not exist (Wiens,
1997). However, it is increasingly apparent that understanding and interpreting ecosystem structure
and process depend on the scale at which measurements are made. There is no single "correct"
scale at which to describe ecological patterns and
processes. In fact, the issue of scale in understanding ecological patterns and processes has been referred to as the "fundamental conceptual problem
in ecology" (Levin, 1992; Christensen et aI., 1996).
As far as relevance to ecosystem management is
concerned, the appropriate scale depends largely on
the management or policy issue in question. Scaling from the leaf to the ecosystem to the landscape
to the region, as well as understanding the transfer
of information, matter, and energy between these
scales, is not only a central question for ecology,
but poses a fundamental issue for ecological assessments.
As difficult as the task may be, simply describing, understanding, and evaluating biophysical patterns and processes are insufficient. Ecosystem
management involves people, their economic and
other activities, and the shared and individual beliefs and behavioral patterns that define their relationship with the land (Slocombe, 1993b). Thus
ecological assessments must create a dynamic portrait that integrates human systems and activities
(social, political, economic, and cultural) with biological and physical systems, replete with patterns, processes, relationships, and trajectories of
change between and among the elements. The picture that emerges from an ecological assessment
must portray an "ecosocial complex" (Haila, 1998)
or "sociobiophysical system" (Grzybowski and
Slocombe, 1988).
The integration task faced by ecological assessments is one of the most difficult challenges confronting both the natural and social sciences and is
at the forefront of the scientific endeavor (Clark et
aI., 1999). The challenge, of course, is not new.
Over the last few decades, some have attempted to
bridge the gap between c.P. Snow's "two cultures"
(Snow, 1993). Such efforts have met with varying
levels of success, although examples of truly integrated interdisciplinary research are rare (Miller,
1994). In the last decade, however, integration efforts have become more intense as both the natural
and social sciences communities realize the necessity of building bridges if they are to answer challenging intellectual questions and address pressing
societal problems (Lubchenco et aI., 1991; Stem et
aI., 1992). Much of the impetus for integration issued from the global change research community,
particularly due to greater recognition that factors
such as land use and land cover change are relevant to all components of global change, from biodiversity loss to altered biogeochemical cycles
(CIESIN, 1992; Riebsame et aI., 1994; Vitousek et
aI., 1997). However, the integration challenge presents itself wherever researchers try to understand
the interaction between ecological and human dimensions of systems at all scales, from local-level
urban systems (Pickett et aI., 1997) to subcontinental regional systems (Slocombe, 1993a; Blood,
1994).
Efforts to integrate across natural and physical
sciences in developing a comprehensive understanding of how systems function confront diffi-
Ecological Assessments and Implementing Ecosystem Management
ficulties involved in characterizing ecological systems to inform management typify a more general
challenge confronting ecological science in the face
of movement to a nonequilibrium or dynamic equilibrium conception of ecological systems (Pickett
et aI., 1992; Fiedler et aI., 1997). It is not enough
simply to describe biophysical characteristics and
patterns. Because ecological systems are inherently
dynamic, characterization must be dynamic as well,
including an understanding of the processes that
create patterns on the land and the spatial and temporal scales at which such processes operate (see
Chapter 1).
If systems are constantly in motion through the
influence of processes such as fire and flooding,
how can an ecological assessment create a portrait
that is helpful both now and in the future? Holling
and Meffe (1996) propose as a golden rule that
"natural resource management should strive to retain critical types and ranges of natural variation in
ecosystems." Historical range of variability is certainly a useful concept for guiding ecological assessments and answering ecosystem management
questions (see Chapter 19). Yet questions remain
as to what a critical type or range of variation is
for a specific system (Holling and Meffe, 1996) and
what factors are most usefully measured to determine historic range of variability in a management
context (Botkin et aI., 1997). Furthermore, applying the concept in some instances is hampered by
lack of data and difficulties in interpreting the historical record (Morgan et al., 1994).
Because ecological systems are dynamic in both
space and time, issues of scale pose a significant
challenge to ecological assessment. Patterns and
processes are manifest at many spatial scales, from
a stand of trees to a watershed to a drainage basin,
and temporal scales may range from a single event
to centuries or more. In the past, many ecologists
were content either to ignore spatial and temporal
heterogeneity altogether or at least to make their
work easier by pretending it did not exist (Wiens,
1997). However, it is increasingly apparent that understanding and interpreting ecosystem structure
and process depend on the scale at which measurements are made. There is no single "correct"
scale at which to describe ecological patterns and
processes. In fact, the issue of scale in understanding ecological patterns and processes has been referred to as the "fundamental conceptual problem
in ecology" (Levin, 1992; Christensen et aI., 1996).
As far as relevance to ecosystem management is
concerned, the appropriate scale depends largely on
the management or policy issue in question. Scaling from the leaf to the ecosystem to the landscape
to the region, as well as understanding the transfer
of information, matter, and energy between these
scales, is not only a central question for ecology,
but poses a fundamental issue for ecological assessments.
As difficult as the task may be, simply describing, understanding, and evaluating biophysical patterns and processes are insufficient. Ecosystem
management involves people, their economic and
other activities, and the shared and individual beliefs and behavioral patterns that define their relationship with the land (Slocombe, 1993b). Thus
ecological assessments must create a dynamic portrait that integrates human systems and activities
(social, political, economic, and cultural) with biological and physical systems, replete with patterns, processes, relationships, and trajectories of
change between and among the elements. The picture that emerges from an ecological assessment
must portray an "ecosocial complex" (Haila, 1998)
or "sociobiophysical system" (Grzybowski and
Slocombe, 1988).
The integration task faced by ecological assessments is one of the most difficult challenges confronting both the natural and social sciences and is
at the forefront of the scientific endeavor (Clark et
aI., 1999). The challenge, of course, is not new.
Over the last few decades, some have attempted to
bridge the gap between c.P. Snow's "two cultures"
(Snow, 1993). Such efforts have met with varying
levels of success, although examples of truly integrated interdisciplinary research are rare (Miller,
1994). In the last decade, however, integration efforts have become more intense as both the natural
and social sciences communities realize the necessity of building bridges if they are to answer challenging intellectual questions and address pressing
societal problems (Lubchenco et aI., 1991; Stem et
aI., 1992). Much of the impetus for integration issued from the global change research community,
particularly due to greater recognition that factors
such as land use and land cover change are relevant to all components of global change, from biodiversity loss to altered biogeochemical cycles
(CIESIN, 1992; Riebsame et aI., 1994; Vitousek et
aI., 1997). However, the integration challenge presents itself wherever researchers try to understand
the interaction between ecological and human dimensions of systems at all scales, from local-level
urban systems (Pickett et aI., 1997) to subcontinental regional systems (Slocombe, 1993a; Blood,
1994).
Efforts to integrate across natural and physical
sciences in developing a comprehensive understanding of how systems function confront diffi-