Download The Ecological Basis of Conservation Heterogeneity, Ecosystems

The Ecological Basis
of
Conservation
Heterogeneity, Ecosystems, and Biodiversity
Edited by
S.T.A. Pickett1 R.S. Ostfeld1
M. Shachak1-2
G.E. Likens1
Institute of Ecosystem Studies
Mary Flagler Gary Arboretum
Millbrook, New York
2
Mitrani Center for Desert Ecology
The Jacob Blaustein Institute for Desert Research
Ben-Gurion University of the Negev, Sede Boker, Israel
E3
CHAPMAN & HALL
X \1) I International Thomson Publishing
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Contents
Foreword: Bruce Babbitt
Preface
x.
Contributors
XV
Participants
xix
I. Introduction: The Needs for a Comprehensive Conservation Theory 1
1. Defining the Scientific Issues
R. S. Ostfeld, S. T. A. Picket!, M. Shachak, and G. E. Likens
2. Part 1. Gretchen Long Glickman—Science, Conservation,
Policy, and the Public
Part 2. H. Ronald Pulliam—Providing the Scientific Information
that Conservation Practitioners Need
Part 3. Michael J. Bean—A Policy Perspective on Biodiversity
Protection and Ecosystem Management
3
11
16
23
3. Conservation and Human Population Growth: What are
the Linkages?
Joel E. Cohen
29
4. Developing an Analytical Context for Multispecies
Conservation Planning
Barry Noon, Kevin McKelvey, and Dennis Murphy
43
5. Operatibnalizing Ecology under a New Paradigm:
An African Perspective
Kevin H. Rogers
60
vi / The Ecological Basis for Conservation
n. Foundations for a Comprehensive Conservation Theory
Themes—S. T. A. Pickett, R. S. Ostfeld, M. Shachak, & G. E. Likens
6. The Paradigm Shift hi Ecology and Its Implications
for Conservation
Peggy L Fiedler, Peter S. White, and Robert A. Leidy
7. The Emerging Role of Patchiness in Conservation Biology
John A. Wiens
8. Linking Ecological Understanding and Application: Patchiness
in a Dryland System
Moshe Shachak and S. T. A. Pickett
HI. Biodiversity and Its Ecological Linkages
themes—R. S. Ostfeld, S. T. A. Pickett, M. Shachak, & G. E. Likens
9. The Evaluation of Biodiversity as a Target for Conservation
M. Philip Nott and Stuart L Pimm
10. Conserving Ecosystem Function
Jui3y MMeyer
11. The Relationship between Patchiness and Biodiversity in
Terrestrial Systems
Lennart Hansson
12. Reevaluating the Use of Models to Predict the Consequences of
Habitat Loss and Fragmentation
Peter Kareiva, David Skelly, and Mary Ruckelshaus
13. Managing for Heterogeneity and Complexity on
Dynamic Landscapes
Norman L. Christensen, Jr.
14. Toward a Resolution of Conflicting Paradigms
S. L. Tartowski, E. B. Allen, N. E. Barrett, A. R. Berkowitz,
R. K. Colwell, P. M. Groffman, J. Harte, H. P. Possingham,
C. M. Pringle, D. L Strayer, and C. R. Tracy
15. The Land Ethic of Aldo Leopold
A. Carl Leopold
TV Toward a New Conservation Theory
Slmes-R S. Ostfeld, S. T. A. Pickett, M. Shachak, and
81
83
93
108
123
125
136
146
156
167
187
193
201
G. E. Likens
..
16. The Future of Conservation Biology: What's a Genemst to Do? 202
Kent E. Holsinger and Pati Vttt
10
Conserving Ecosystem Function
Judy L. Meyer
Summary'
Successful conservation efforts require a consideration of ecosystem function.
In this chapter, I present seven principles from ecosystem science to serve as a
foundation for ecosystem conservation:
1. Ecosystems are open, which should lead to an emphasis on conserving
the fluxes across ecosystem boundaries and linkages with surrounding ecosystems.
2. Ecosystems are temporally variable and continuously changing; the
present bears the legacies of past disturbances.
3. Ecosystems are spatially heterogeneous on a range of scales, and essential processes depend on that heterogeneity.
4.
Indirect effects are the rule rather than the exception in most ecosystems.
5. Ecosystem function depends on its biological structure.
6. Although several species perform the same function in ecosystems, they
respond differently to variations in their biotic and abiotic environment,
thereby reducing variation hi ecosystem function in a changing environment.
7. Humans are a part of all ecosystems.
A river restoration project provides an example of the use of ecosystem principles
to design effective conservation strategies; yet we have little experience with the
use of measures of ecosystem structure or function to measure the efficacy of
conservation efforts. Research is needed to find appropriate metrics and to determine their range in regional reference systems. A critical first step in using such
136
Conserving Ecosystem Function / 137
an approach is to identify and preserve a wide range of ecosystems that could
be used for regional references. Unanswered questions remain that limit our
ability to use measures of ecosystem structure and function to guide conservation
practices. Finding answers to these questions is critical because the public values
the goods and services that are a consequence of ecosystem function.
Introduction
Conservation must consider the ecosystem if it is to be successful. Species
networks exist in geologic, hydrologic, climatic, and chemical contexts. The total
biological diversity on Earth is in part a consequence of heterogeneity in abiotic
features of the planet. For example, the heterogeneity inherent in a stream is a
consequence of its geomorphology, hydrology, and chemistry: different plant
and animal communities occupy bedrock outcrop versus depositional areas (Huryn
and Wallace, 1987); hydrologic regime influences the outcome of food web
interactions (Power, 1992); and patterns of nutrient upwelling from the sediments
alter the distribution and abundance of algae (Pringle et al., 1988). Without the
understanding gained from analysis of the physical and chemical setting as
well as the biological and societal context, conservation efforts are doomed.
Attempting to conserve a wetland bird species without understanding the wetland's hydrologic regime would be courting failure.
To say it as provocatively as possible: conservation will fail if it is the exclusive
territory of biologists. Conservation ecology requires expertise from hydrology,
geology, geochemistry, meteorology, history, sociology, and other disciplines as
well as from the traditional biological sciences.
Many other arguments have been offered for why we must manage at the
ecosystem scale (Grumbine, 1990). For example, Franklin (1993b) offers two:
there are too many species to deal with them individually and the ecosystem
approach offers an effective way to conserve poorly known species and habitats
(e.g., belowground).
Despite the declared need for an ecosystem perspective, ecosystem principles
are rarely presented in papers and books dealing with conservation; for example,
May's (1994b) discussion of ecological principles relevant to the management
of protected areas stopped at the level of communities. Hence I begin by outlining
a set of basic ecosystem principles that could serve as a beginning foundation
for ecosystem conservation. I explore by example how these principles have
been and could be used as a basis for effective conservation efforts and then
consider possible measures of ecosystem function that could guide future conservation efforts. My focus hi this chapter is on ecosystem function, what environmental ethicists term the "instrumental value" of nature (producing goods and
services of value to humans) (Callicott, 1989). Nature's "intrinsic values" are
equally worthy of preservation.
138 / Judy L Meyer
Basic Principles From Ecosystem Science
What are some principles of ecosystem science on which to base a theory of conservation?
• Ecosystems are open to flows of energy, elements, and biota.
Application of this principle requires consideration of the fluxes across ecosystem boundaries and identifying linkages with surrounding ecosystems. There are
examples of successful management based on this principle. One is the Clean
Water Act, which, among other things, regulates the inputs of nutrients into our
nation's waters. Although it is far from perfect, in part because it does not
adequately cover diffuse fluxes across ecosystem boundaries (i.e., nonpoint
sources), this act has had a positive impact on the preservation and improvement
of aquatic ecosystems in the United States.
There are also situations in which our current conservation policy does not
adequately consider fluxes. For example, U.S. Department of Agriculture (USDA)
quarantine officials are charged with inspecting material crossing our borders to
intercept pests that pose a threat to species of economic importance; as explained
to me by a frustrated quarantine officer, there is no mention of ecological or
evolutionary importance, only economic. Although we outlaw trade in endangered
species, U.S. quarantine officers do not have the authority to block the importation
of species that pose a threat to our native flora and fauna.
The Wild and Scenic Rivers Act is another example of a conservation action
that did not adequately take into account fluxes across boundaries. The act protects
reaches of rivers, but does not protect the river above or below the reach of
concern or the watershed as a whole. The reach is vulnerable to poor agricultural
practices in the headwaters that add nutrients and sediments or to toxic emissions
or dams downstream that restrict the migration of anadromous species. This
became apparent to conservation groups who had fought hard for protection of
rivers under this act, and then found themselves unable to truly protect the river.
Hence many adopted an ecosystem perspective to seek solutions that will protect
more than just the reach (e.g., Doppelt et al., 1993).
• Ecosystems are continuously changing; yet the present bears the legacies
of the past.
Failure to adequately consider this principle has lead to misguided conservation
strategies (e.g., fire exclusion), which have been thoroughly discussed elsewhere
(Botkin, 1990; Pickett et al., 1992; Meyer, 1994). Although disturbance is now
recognized to be a part of natural ecosystems, human disturbance can not simply
be substituted for natural disturbance (Ewel, this volume); logging an old growth
forest is not the same disturbance as a lightning-ignited fire.
The legacies of past disturbances (e.g., beaver removal; Naiman et al., 1988)
Conserving Ecosystem Function / 139
is whatMagnuson (1990) has called the "invisible present." Finding that "invisible
present" requires us to look in the past, to do some historical reconstruction, and
design our conservation strategy accordingly. I provide an example of that process
at work in a river basin later.
• Ecosystems are spatially heterogeneous on a range of scales, and
ecosystem structure and function depend on that heterogeneity.
To a stream ecologist, spatial heterogeneity is an obvious fact of life (e.g.,
Pringle et al., 1988). The communities of benthic invertebrates and the relative
rates of key ecosystem processes like primary production and respiration vary
at scales ranging from the landscape to an individual rock on the stream bed.
This variability is a function of the geographical setting of the river basin (e.g.,
Minshall et al., 1983), where you are in the river network (e.g., Naiman et al.,
1987, Meyer and Edwards, 1990), the nature of the stream reach (e.g., constrained
or unconstrained), and the nature of the substrate (e.g., bedrock versus a pool).
This hierarchy of spatial heterogeneity has been well classified, categorized, and
used to guide stream research and conservation (Frissell et al., 1986; Hawkins
et al., 1993; Rogers, this volume). Critical ecosystem processes depend on it.
For example, the nitrogen cycle depends on spatial heterogeneity hi oxygen
content: nitrification proceeds in oxygenated environments whereas denitrification
occurs where there is little or no oxygen. Elimination of this spatial heterogeneity
(e.g., by channelization) alters both structure and function of the riverine ecosystem (Allan, 1995).
• Indirect effects are the rule rather than the exception in most ecosystems.
The conservation message hi this principle is that disruption of one part of an
ecosystem will have broader repercussions. Ecosystems are not assembled at
random. They are the product of a long history of interaction (e.g., Thompson,
this volume). It is the province of ecologists to assess the strength of those
interactions among both biotic and abiotic components of the ecosystem. This
principle has been well documented in experimental manipulations of lakes,
where alteration of vertebrate predator abundance impacts not only abundance
of their zooplanktivorous prey but also abundance of zooplankton and algae as
well as lake temperature regime (Mazumber et al., 1990) and sedimentation rates
(Pace et al., 1995). Ecologists are most familiar with the importance of indirect
effects in species interactions (e.g., Wootton, 1992); yet there can also be indirect
effects in elemental cycles. For example, alterations in sulfur deposition can
impact phosphorus burial in lake sediments (Caraco et al., 1991), and the presence
of deep-burrowing fauna alters the ratio of pyrite to carbon in marine sediments
(Giblin et al., 1995).
140 / Judy L. Meyer
• The function of an ecosystem depends on its biological structure; species
do not have equal effects on ecosystem function; and an organism's size is
not a good indicator of its influence on ecosystem function.
A recent study in a stream experimentally altered by pesticides offers a striking
example of the relationship of function to structure (Wallace et al., in press).
Values of an index of macroinvertebrate community structure increased and
decreased coincidentally with a measure of ecosystem function (seston concentration, which reflects rate of organic matter processing). The second part of this
principle is a restatement of keystone species concept, which has been thoroughly
explored elsewhere (e.g., Bond, 1992). The third part is a recognition of our
dependence on the microbes of the world for essential functions like nutrient
regeneration. The application of this principle by conservationists broadens their
focus well beyond the charismatic megafauna.
• Although several species perform the same function in ecosystems, they
respond differently to variations hi their biotic and abiotic environment,
thereby reducing variation in ecosystem function in a changing
environment.
When lakes were experimentally acidified, primary productivity changed relatively little, despite striking changes in algal species composition (Schindler,
1990). A similar phenomenon has also been observed hi a stream being recolonized after experimental alteration of invertebrate assemblages with pesticides:
the same rates of leaf decay were observed despite shifts in the species of
invertebrates consuming the leaves (Wallace et al., 1986). In this case, recovery of
ecosystem function (rate of leaf decay) occurred more rapidly than did taxonomic
recovery. In experimental plots in Costa Rica, the first several species added to
the plots greatly altered ecosystem function; but after the first few species, there
was little change (Ewel et al., 1991; Vitousek and Hooper, 1992). In all of these
examples, one is tempted to view the array of species performing the same
function as functionally redundant, but they are not. This becomes apparent when
ecosystem function is considered in a longer time frame and in the context of
environmental change. For example, zooplankton species that appeared after
acidification of a lake were those that had been rare earlier (Frost et al., 1995).
They may have appeared to be a small and functionally redundant part of the
assemblage of grazers before acidification, but were a dominant member of the
assemblage when environmental conditions changed.
The conservation message is clear: one goal for conservation is maximization
of functional redundancy because that offers the best insurance for maintenance
of ecosystem function in a changing environment. The diversity represented by
today's rare species relates to future ecosystem function in an environment altered
by natural or anthropogenic processes.
Conserving Ecosystem Function / 141
• Humans are a part of all ecosystems.
Not only have we altered Earth's ecosystems, we are also dependent on them.
This is a principle we ecologists have finally assimilated into our research agendas
(Lubchenco et al., 1991; Naiman et al., 1995), which acknowledge the impact
of human activity on the biosphere and the need to understand its effect Ecologists
recognize that we can no longer study pristine environments, for there are none
(Vitousek, 1994).
This principle is recognized to be of critical importance in conservation ecology
(e.g., Meffe and Carroll, 1994). Conservation is essentially management of human
activity hi the landscape, so to ignore the societal context for conservation efforts,
is to invite failure. The success of conservation efforts often rests on their ability
to incorporate indigenous peoples, whether they are tribes in the Amazon or
ranchers on the borders of Yellowstone National Park.
I offer these as a beginning set of ecosystem principles that can be combined
with already elaborated principles from genetics (e.g., Holsinger and Vitt, this
volume), population biology (e.g., Nott and Pimm, this volume), and community
ecology (e.g., Simberloff, this volume) to broaden the scientific basis for conservation.
Applying These Principles To Conservation
How might an understanding of ecosystem function be used to design better
conservation strategies? I offer an example from a river restoration effort on
Knowles Creek in Oregon. This is a project conceived and carried out by Charley
Dewberry of the Pacific Rivers Council working with staff from the Siuslaw
National Forest and Champion International, a timber products company (Dewberry, 1995, 1996). This project is unique in that their efforts have been directed
at understanding and recreating long-term ecosystem processes while recognizing
that emergency stopgap measures are necessary hi the short term.
Knowles Creek is a tributary of the Siuslaw River, draining the western slopes
of the Cascade Mountains. It has populations of coho salmon, chinook salmon,
and steelhead and cutthroat trout. The project began with a historical reconstruction: What were the key functional processes hi the basin prior to European invasion?
The basin can be divided into valley and upland. Sediments from the uplands
collected in hollows, which pulsed the accumulated sediment load into the valley
hi debris torrents at about 6,000-year intervals. The debris torrent stopped hi
the tributary junction with the mainstem or when it contacted the huge cedars
characteristic of the riparian zones of the valley floor. Hence certain sites in the
basin were the "geomorphic control points" with extensive flats behind them that
provided essential backwater habitat and areas of high aquatic productivity. These
areas also helped control stream temperatures by storing large amounts of water
142 / Judy L Meyer
in the sediments. But the flats were not permanent features; eventually the debris
dams that formed them would be breached, the flat cut down to bedrock, and
the material it had held was pulsed downstream to the next flat.
When the first European settlers arrived in the 1870s, the basin was recovering
from extensive fires of the previous decade, fires that naturally recur every century
or two. Because of increased erodability after fires, it is likely that the uplands
were supplying considerable sediment to the valley floor at this time. Flooding
of the valley floor occurred frequently: a flood triggered by typical June rainstorm
in the 1880s would require a 75-year storm today. Logging in the valley floor
altered its sediment storage capacity, and the channel downcut rapidly. Logging
and roadbuilding in the uplands was intense from 1950 to 1985, delivering two
centuries worth of sediments to the channel in a period of 35 years. With reduction
in storage capacity of the valley floor, those sediments were lost from the basin
and with them was lost essential habitat for salmonids.
In this stream, where around 100,000 coho smolts would be expected to migrate
to the ocean, only 1,660 did in 1982. So in the 1990s we are left with an upland
that has recently lost much of its erodable sediment and a valley floor that has
little capacity to store sediment, resulting in loss of productive habitat, accentuated
low flows and elevated water temperatures.
What conservation/restoration decisions have been made based on this understanding of ecosystem processes?
1. Protect the intact areas to serve as refuges while the basin recovers.
2. Begin the recovery process in the valley floors by replanting cedars,
beginning a process that wDl take a century before its full impact will
be felt.
3. Manage uplands to reduce likelihood of major debris torrents in the
next century.
4. Simulate debris torrent deposits at sites at the geomorphic control points
where they would have naturally occurred. This involved
a. identifying areas where flats were likely to be formed and would
remain at least 50 years,
b. spacing the flats so that a couple tributaries could contribute sands
and gravel to each,
c. choosing sites that would give greatest immediate storage for the least
investment in material, and
d. choosing sites that posed the least threat to existing roads and bridges.
Ten sites were identified. Crews cabled in a few key pieces of downed timber
at each site to mimic the huge immovable trees that would previously have
provided the structural stability for the deposit, but the rest of the debns was
allowed to move and set up again at the next flat downstream. All major flats
AA
Conserving Ecosystem Function / 143
have been mapped, and all large pieces of wood tagged so their movements can
be followed. The number of coho salmon smolt is being monitored, because that
was chosen as the biological response variable. The debris dams have functioned
as predicted, trapping sediments during a major storm in January 1995 that
approached the storm of record hi its magnitude.
This project has elements of many of the principles I discussed: it recognizes the
openness of ecosystems and linkages between different ecosystems, the temporal
variability of important habitat features (the flats), the importance of an historical
perspective, the spatial heterogeneity of systems, the importance of productivity
of the smallest members of the food web, and incorporation of the human element
Using Measures of Ecosystem Function As A Target For Conservation
The previous example demonstrates how we can use an understanding of ecosystem function to guide conservation practices. Yet the tough question remains:
Can we use measures of ecosystem structure or function as a target for and a
way of assessing the efficacy of conservation efforts? The goal is to find measures
of ecosystem structure and function with sensitivity, diagnostic capacity, and
ability to offer early warning of problems (Nip and de Haes, 1995). Yet there
are examples of extremely useful indicators that do not meet all these criteria;
for example, atmospheric CO2. Its utility as an indicator has been demonstrated;
yet it has little diagnostic capacity. We are still arguing about which human
activity causes elevated atmospheric CO2. Finding indicators that meet all these
criteria is a challenge that those interested in detecting effects of toxins on
ecosystems have been facing for decades. What have they learned?
1. Seek not a single metric. What is needed is a suite of measures that indicate
the function of a facet of the ecosystem of concern (Kelly and Harwell, 1990).
We are not going to find a single index that will measure the "pulse" of an
ecosystem. In our search for measures, it is important to recognize the diversity
of ecosystems on the planet and devise measures of local interest so that our
management can be particularistic; that is, guided by the peculiarities of the site
(Norton, 1992)
2. Consider the structure of the food web as a whole or those portions leading
to species of interest, which could be native or endemic species. For example,
evidence from a thermally altered river shows the number of links in the food
web as the variable showing the greatest change under an altered thermal regime
(Ulanowicz, 1992).
3. Look to key geochemical processes. Biological oxygen demand (BOD) has
been a useful indicator of threats to stream ecosystems from organic pollution
for decades; significant improvement in lakes has been achieved by controlling
the supply of phosphorus to the biota. We need additional indicators of system
geochemistry because they can tell a manager about the availability of essential
144 / Judy L Meyer
elements to species of concern. In the forests of the eastern United States, the
nitrogen cycle seems to be a sensitive indicator of change. Nitrate losses have
been seen in response to the human disturbance of logging, as well as to the
invasion of defoliators such as the gypsy moth or the fall cankerworm (Swank
and Crossley, 1988). Nitrogen mineralization is a key process that supplies
biologically available nitrogen to the ecosystem. Hence indicators that consider
the forms, stocks, or recycling of essential elements such as nitrogen or phosphorus offer promise.
4. Indicators of productivity and physiological or reproductive function in key
species provide an early warning of problems. This has been clearly demonstrated
in lake acidification research (Schindler, 1990), where, for example, periphyton
productivity was a sensitive and early indicator of acidification. The greatest
alterations in ecosystems resulted when species without functional analogs in the
system were eliminated (Schindler, 1990); these are the species whose productivity and physiology offer the most promise as indicators.
5. Look to the resource base: has there been a shift hi the relative importance
of allochthonous versus autochthonous energy resources? In the thermally altered
Crystal River, there was a shift from detritivory to herbivory (Ulanowicz, 1992).
New techniques of stable isotope analysis offer promise for indicators to detect
these kinds of changes: hi streams, delta13C signatures of samples of benthic
invertebrates could be used to detect shifts in the relative importance of allochthonous and autochthonous carbon sources (Bunn, 1995).
6. Look to key processes. In streams draining forested catchments, leaf litter
decay is a key process. Decades ago, Egglishaw demonstrated the connection
between nutrient concentration, fungal degradation of a standard C source, and
trout growth (Kelly and Harwell, 1990). Decreases in fungal diversity or activity
in a system like this indicates a serious threat to the food web.
7. Look to abiotic regulators of key processes. Temperature is of course the
most basic, but hi lakes and streams, measures of water residence time are critical.
For example, transient storage zones hi streams (e.g., pools forming behind debris
dams, deep gravel beds that exchange water with the surface) alter the length of
time water is hi contact with stream sediments, thereby affecting the ability of
sediment biota to take up nutrients (D'Angelo et al., 1993). An alteration in
volume of transient storage zones caused by changes hi channel structure will
eventually be manifested in reduced capability for nutrient uptake and storage.
8. Look to biotic regulators of key processes. Indicators of the condition of
some of the "engineer" species (such as beavers, woodpeckers, earthworms and
other burrowers; e.g., Lawton and Jones, 1995) offer insight into the future
condition of the ecosystem.
9. Look for integrators. Atmospheric CO2 is an example of an indicator that
integrates human activity over a broad scale. Similarly, aquatic systems can serve
as integrators of management of terrestrial landscapes (Naiman et al., 1995).
Conserving Ecosystem Function / 145
Indices of the integrity of the aquatic biota offer tools to assess the cumulative
impact of watershed management practices (e.g., Rosenberg and Resh, 1993).
10. Expect the unexpected. Disturbances are a feature of the natural world
that cause changes in ecosystems, only some of which we are able to predict.
Yet they also offer valuable insight into the mechanisms driving observed patterns.
This list is not a primer of measures of ecosystem function that offers useful
targets for conservation. We are not yet ready to write that primer. Still needed
are further development, testing, and application of measures of ecosystem function that could serve as targets for ecosystem conservation hi a wide range of
environments. These will add to the effectiveness of our conservation toolbox.
Assuming we add these measures to our toolbox, what numeric values of the
measures should management seek to achieve? Here there is a deceptively simple
answer: the range of values observed in regional reference systems. A critical
first step in taking such an approach is to identify and preserve a wide range of
ecosystems that could be used for regional references (Christensen, this volume;
Barrett and Barrett, this volume; Thompson, this volume). These ecosystems
provide us with the baselines we need for evaluating our compliance with environmental laws and for assessing the efficacy of conservation and restoration efforts.
Ecosystems with minimal human impact offer us the moving target we need to
design and evaluate restoration and conservation efforts. By referencing our
activities to an ever-changing natural system, we are incorporating into our
management scheme one of the basic principles presented earlier, the temporal
variability of ecosystems.
By considering ecosystem function in addition to evolutionary heritage, conservation will also broaden its list of places worthy of protection. Conservation of
systems that provide essential ecosystem services will receive increased attention.
We may also want to consider conservation of ecosystems with unique functional
attributes, because these are places where we are likely to find species with unusual
characteristics that could be beneficial to humankind. Extreme environments,
such as hot springs, offer a unique environment selecting for unusual functional
adaptations; this is an environment that has already yielded products of economic
benefit to humans. It would be fruitful to seek out and conserve environments
that are likely to select for organisms with unique functional attributes.
Unanswered questions remain that limit our ability to use measures of ecosystem structure and function to guide conservation practices. Finding answers to
these questions is both intellectually challenging and critical to the success of
conservation efforts because the ecosystem goods and services valued by the
public are a consequence of ecosystem function. Conservation will enjoy wider
public support if we are able to relate conservation efforts to services the public
cares about, such as providing clean water, clean air, and productive soils (Harte,
this volume). These are the products of conserving ecosystem function.