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OCR for page 64
Colloquium
Rapicl plant cliversification: Planning for an
evolutionary future
R. M. Cowling*t and R. L. Pressey:
*Terrestrial Ecology Research Unit, Botany Department, University of Port Elizabeth, P.O. Box 1600, Port Elizabeth 6000, South Africa; and $New South
Wales National Parks and Wildlife Service, P.O. Box 402, Armidale, New South Wales 2350, Australia
Systematic conservation planning is a branch of conservation biology
that seeks to identify spatially explicit options for the preservation of
biodiversity. Alternative systems of conservation areas are predic-
tions about effective ways of promoting the persistence of biodiver-
sity; therefore, they should consider not only biodiversity pattern but
also the ecological and evolutionary processes that maintain and
generate species. Most research and application, however, has fo-
cused on pattern representation only. This paper outlines the devel-
opment of a conservation system designed to preserve biodiversity
pattern and process in the context of a rapidly changing environment.
The study area is the Cape Floristic Region (CFR), a biodiversity
hotspot of global significance, located in southwestern Africa. This
region has experienced rapid (post-Pliocene) ecological diversification
of many plant lineages; there are numerous genera with large clusters
of closely related species (flocks) that have subdivided habitats at a
very fine scale. The challenge is to design conservation systems that
will preserve both the pattern of large numbers of species and various
natural processes, including the potential for lineage turnover. We
outline an approach for designing a system of conservation areas to
incorporate the spatial components of the evolutionary processes
that maintain and generate biodiversity in the CFR. We discuss the
difficulty of assessing the requirements for pattern versus process
representation in the face of ongoing threats to biodiversity, the
difficulty of testing the predictions of alternative conservation sys-
tems, and the widespread need in conservation planning to incorpo-
rate and set targets for the spatial components (or surrogates) of
processes.
There are numerous pleas in the literature for integrated systems
of conservation areas that will maintain disturbance regimes,
migratory corridors, habitat diversity, landscape connectivity, evo-
lutionary templates, and other spatial features necessary for the
maintenance of evolutionary processes (1-4~. There has been some
debate as to whether priority should be given to areas supporting
ancestral taxa with evolutionary potential (5, 6) or those represent-
ing evolutionary fronts of currently speciating taxa (7-10~. Re-
cently, Moritz and coworkers (11) have used comparative phylo-
geography to identify areas that encompass both the adaptive and
historical components of genetic diversity of vertebrates in the
rainforests of northeastern Australia. However, there have been no
studies that attempt to identify the spatial components of a wide
spectrum of evolutionary processes or to set explicit targets for their
protection in particular regions.
If we are to plan for an evolutionary future, then evolutionary
processes those that maintain genetic diversity and promote
diversification must be explicitly considered, and represented,
in the conservation plan (1, 11, 12~. This is not a trivial issue.
There are very few places in the world, in particular in its
endemic-rich and threatened regions (13), where evolutionary
processes and their spatial components are understood well
enough to be included in conservation planning. Over the past
few decades, considerable insights have been gained regarding
evolutionary processes in the Cape Floristic Region (CFR) of
5452-5457 1 PNAS 1 Maya, 2001 1 vol. 98 1 no. 10
South Africa, especially for plants. Because the available data
are representative of most plant lineages in the region, they
provide a good basis for conservation planning.
In this paper, we provide a brief overview of evolutionary
processes in the CFR, a species-rich region that is recognized as
a global priority for conservation action (13~. We focus in
particular on rapid diversification of plant lineages. We then
review briefly some recent developments in systematic conser-
vation planning and the need to extend these ideas to apply not
only to biodiversity pattern, but also to ecological and evolu-
tionary processes. Because conservation planning is a spatially
explicit exercise, even processes must be protected by their
spatial components or surrogates. Accordingly, we describe a
framework for planning for an evolutionary future in the CFR,
identifying seven types of spatial components of evolutionary
processes, setting explicit conservation targets for each, and
outlining the development of a conservation plan to achieve
these targets. We conclude by discussing the difficulty of testing
predictions about biodiversity persistence deduced from alter-
native conservation plans, the contributions of the approach
presented here, and its potential for widespread application.
Rapid Diversification in the CFR
Rapid diversification, often associated with key innovations and
leading to flocks of species that show fine-scale habitat discrimi-
nation, has been reported for some plant lineages (26-28), espe-
cially on islands (29, 30), for Andean birds (9), and for fish, most
notably the cichlids of the African Rift Lakes (19~. Without a doubt,
the distinctive evolutionary feature of the CFR is the recent and
massive diversification of many plant lineages (20, 21~. The region
includes some 9,000 plant species in 90,000 1~12, 69% of which are
endemic (21) one of the highest concentrations of endemic plant
species in the world (13~. This diversity is concentrated in relatively
few lineages that have radiated spectacularly. Thus, 13 genera (of
a total of 988) each comprise more than 100 species, and together
these account for 25% of all species in the flora (21~. Similarly, of
the region's 173 families, 12 each comprise more than 200 species
and, in combination, indude 64% of the CFR's flora.
Although the evidence is patchy, it seems certain that this
massive diversification has occurred relatively recently, mostly
after climatic deterioration in the late Pliocene when seasonal
(Mediterranean-type) climates developed and recurrent fire
became an important ecological factor (22, 23~. That many
lineages are in the midst of massive diversification events is
suggested by the restriction of localized endemics to very young
sediments (20), the large clusters of closely related species
resulting in poor phylogenetic resolution in Glades (24, 25), and
This paper was presentecl at the National Acaclemy of Sciences colioqulum, "The Future of
Evolution," helc! March ~ 6-20, 2000, atthe Arnoic' anc] Mabe! Beckman Center in irvine, CA.
Abbreviation: CFR, Cape Fioristic Region.
tTo whom reprint requests shouIc' be adciresseci. E-maii: rmc~kingsiey.co.za.
www.pnas.org/cgi/cioi/ ~ 0. ~ 073/pnas. ~ 01093498
OCR for page 65
a very recent (post-Pleistocene) appearance in the pollen record
of species-rich taxa, notably the Mesembryanthemaceae (26~.
Diversification-prone lineages in the CFR are not a random
assemblage either biologically or ecologically. Generally, com-
ponent species among woody groups are low, fire-killed (i.e.,
nonsprouting) shrubs with poorly dispersed seeds, small and
weakly persistent seed banks, and insect-pollinated flowers (21,
27, 284. These traits, especially fire sensitivity, which could be
regarded as a key innovation (in the sense of ref. 29; see also refs.
22 and 27), have favored increased diversification rates. Thus,
fire-induced plant mortality increases generation turnover,
thereby providing potential for more rapid evolution than
sprouters (compare refs. 27 and 30~. Small and weakly persistent
seed banks, in combination with fire sensitivity, result in non-
overlapping generations, thereby increasing the probability of
the manifestation of genetic novelties associated with each
generation, as well as increasing the probability of population
fragmentation via fire-induced local extinction (22, 274. Finally,
restricted gene flow, a consequence of short-distance seed
dispersal and insect pollination, promotes isolation and hence
diversification of populations in different habitats (31, 32~.
A simple microgeographic speciation model applies (28~: sub-
populations of common species, presumably with considerable
genetic diversity, are isolated geographically by fire-induced local
extinction or climate change, on the periphery of the parent
population in a different habitat. This process can occur very rapidly
(even after a single fire) and, owing to limited gene flow, over small
spatial scales. In these isolated populations, a combination of
chance fixation of new genes and strong selection in a different
habitat results in rapid speciation. Predictably, the overwhelming
majority of range-restricted, terminal taxa are habitat, principally
edaphic, specialists (20, 27, 33, 35), implying a strong ecological
component to the diversification processes (21, 31, 34~.
Adaptation to pollinators has also played a major role in the
diversification of the CFR's flora (35~. This is especially true of
the region's large geophyte flora (ca. 1,500 species) where
specialist pollinators have driven speciation in several groups
(e.g., refs. 36-38~. Strong selection for specialist pollinators is
presumably a consequence of the scarcity of pollinators and
widespread pollen limitation in the infertile and fire-prone CFR
landscapes (39~. However, ecological factors, especially soil type,
may nonetheless play an overriding role in speciation amongst
geophytes, as in the irid genus Lapeirousia (33~.
Diversification of the CFR biota has also occurred in relation
to meso- and macroscale ecological gradients, also operating
over larger temporal scales than those described above. These
larger processes are the consequence of geographic isolation
driven by oscillating climate change during the Pleistocene (21,
40~. There is some evidence for ecological diversification of both
plant and invertebrate lineages in relation to the high environ-
mental diversity associated with lowland-upland gradients (6,
34, 41~. Riverine systems that breach montane migration barri-
ers, thereby linking dry interior basins with mesic coastal fore-
lands, are important for migration and exchange between these
biotas: subsequent isolation of populations may also play a role
in speciation (42~. Plants and invertebrates have also diversified
across the macroclimatic gradients evident in the CFR (41, 43~.
There may also be as yet undisclosed levels of within-species
genetic variation between geographically isolated parts of
the CFR.
Further rapid climate change is likely to cause the extinction
of many of the range-restricted and habitat-specialist members
of the actively speciating flocks in the CFR (44-47~. However,
by changing habitat characteristics and promoting population
isolation, climate change may also enhance turnover of actively
diversifying lineages. Another widespread influence is ongoing
transformation of habitats to intensive uses. The challenge for
conservation planning is, therefore, to create conditions that
Cowling and Pressey
enable evolutionary processes to continue in a rapidly changing
world (48~.
Systematic Conservation Planning
Conservation planning is a branch of conservation biology that
seeks to identify spatially explicit options for the preservation of
biodiversity (49, 50~. Alternative systems of conservation areas are,
in essence, hypotheses about effective ways of promoting the
persistence of biodiversity. It is vital, therefore, that planning
considers not only the representation of populations, species,
and other components of biodiversity pattern, but also—as we
argue below the processes that underpin these patterns. In order
for these processes to be represented in a conservation plan, they
must be explicitly identified by their spatial components [e.g., a
particular physiographical gradient across which lineages have
diversified (9, 12~.
Invariably, the conservation options arising from a plan are
constrained by a number of factors, such as the existing reserve
system (51), the extent and configuration of transformed habitat
(52), and forms of land use that are financially more viable (at
least in the short term) than conservation (53~. To be effective,
conservation planning should be systematic. Systematic ap-
proaches share the following features: they are data-driven;
target-directed; efficient; explicit, transparent, and repeatable;
and flexible (12, 54~.
A map of irreplaceability, such as the one shown in Fig. 1, is
an outcome of a systematic approach that presents options for
planning new protected areas (55~. Essentially, irreplaceability is
a measure assigned to an area that reflects its importance, in the
context of the planning domain (e.g., the CFR), for achieving a
set of regional conservation targets (e.g., a specified extent of
each habitat type). Irreplaceability can be defined in two ways
(574: the likelihood of an area being required to achieve the set
of conservation targets for the region; and the extent to which
the options for achieving a system of conservation areas that is
representative (achieves all of the conservation targets) is re-
duced if that area is lost or made unavailable.
In areas of high irreplaceability, all or most extant habitat is
required to achieve targets; in areas of low irreplaceability, there is
greater flexibility in the array of available areas required to meet
regional conservation targets (55~. In the case of the CFR (Fig. 1),
the broad pattern of irreplaceability is largely driven by agricultural
transformation. Areas comprising habitat types that have been
almost entirely transformed mainly renosterveld and allied shru-
blands of the coastal lowlands (58) have maximum irreplaceabil-
ity. All extant occurrences of these habitats are required to fulfill the
conservation target, and options for protected area establishment,
or some form of conservation action, are severely constrained. In
contrast, sites that include habitats associated with remote and
infertile mountain landscapes, which are in a largely pristine state
and where most protected areas are located (59), have low irre-
placeability: here there are numerous options to meet the outstand-
ing conservation targets.
Although the analysis in Fig. 1 provides a solid base for
systematic conservation planning, it has a major limitation. The
outcome reflects the options for achieving targets for pattern
only. The representation of biodiversity pattern (species, habi-
tats, etc.) is only one component of an effective conservation
plan; an explicit consideration of the evolutionary processes that
will maintain biodiversity in the long term is also required (11,
12), especially in a world that is increasingly threatened by
habitat loss and climate change (44, 454.
Planning for Ecological and Evolutionary Processes
The past 20 years have seen the development of systematic
conservation protocols that identify whole sets of complemen-
tary areas that collectively achieve some overall conservation
goal the "minimum set" approach (49, 60~. In this strategy, the
PNAS 1 May 8, 2001 1 vol 98 1 no 10 1 5453
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.~ ~ ~ ~ ~ ~,~ ~,~,~ ~ ~ ~.
. . ~ ~ ~ ~-~ ~.~ ~ ~ ~ ~.
.~ ~ ~-~ ~ ~.~ ~ ~ ~ ~ ~.~ ~ ~.~
~c~ ~
~:~ ~ ~ =:~ ~ ~:
: ~ ~ ~ ~—~ ~ ~:~:
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:~: ~ ~ ~ ~:~
:~ ~: i~
~:~ ~ ~ :~:~ ~ ~ ~
~ ~;~` ~ ~ ~ ~
~:~ ~ ~::~ - ~:~ ::~: :~
~v:
:~.~ ~ ~ ~ ~ ~ ~ ~ ~ ~:~
S~ ~ ~ :~ ~:~: :~ ~ :~:~::
:~ ~ ~ ~ ~ ~:~:
::: :~:~:~:: :~:~: ~:~ ~ :~ ~:~::: :~
OCR for page 66
To
Mandatory Reserve
Site Irreplaceability
>0.8 - 1
>0.4 -~0.8
>0 2 - 0 4
, .... ,,,,,,,
:
:~ it_ :~
Fig. 1. A map of site irreplaceability for the CFR. Areas (planning units comprising 1/16° cells) where existing reserves cover >50% of the area are regarded
as mandatory reserves. Totally irreplaceable units include areas of habitat that are essential to meet reservation targets, whereas units where irreplaceability
is zero comprise habitat for which reservation targets have been achieved. The analysis, driven by explicit reservation targets for 88 Broad Habitat Units (BHUs),
and mapped at 1:250,000 (56), was undertaken by using C-PLAN, a decision support system linked to a geographic information system (53).
conservation goal consists of quantitative targets for each spe-
cies (e.g., at least one occurrence) or each habitat (e.g., at least
10% of its total area). The aim is to represent the required
amount of each species or habitat in as small an area as possible.
Usually, rapid implementation of the reserve system is assumed
implicitly, so there is no basis for deciding how to schedule
conservation action among the selected areas in relation to
prevailing threats.
A more realistic scenario, however, is for implementation of
the reserve system to take years or decades, during which time
the agents of biodiversity loss continue to operate. In such
situations, strategies for maximizing representation on paper
must be complemented or replaced by those that maximize
"retention" in the face of ongoing loss or degradation of habitat.
A crucial consideration in maximizing retention is the assign-
ment of priorities based on the irreplaceability of a site and its
vulnerability to biodiversity loss as a result of current or im-
pending threatening processes (61~. In this scenario, areas with
high irreplaceability and high vulnerability are the highest
priorities for conservation action. The objective of the approach
is to minimize the extent to which representation targets are
compromised by ongoing loss of habitat and species. The same
rationale underlies some approaches to identifying conservation
areas globally (13 ).
A further step is needed, however, for conservation planning
to truly address the long-term persistence of biodiversity. The
implementation of reserve systems that are designed to retain
only biodiversity pattern will not ensure long-term conservation.
This is because these systems do not explicitly consider the
ecological and evolutionary processes that maintain and gener-
ate biodiversity (1, 3, 11, 12, 62~. The ultimate goal of conser-
vation planning should be the design of systems that enable
biodiversity to persist in the face of natural and human-induced
change. Design is defined here as the size, shape, connectivity,
orientation, and juxtaposition of conservation areas intended to
address issues such as viable populations, minimization of edge
effects, maintenance of disturbance regimes and movement
patterns, continuation of evolutionary processes, and resilience
to climate change.
Given that the implementation of reserve systems is almost
always gradual, and accompanied by ongoing loss of habitat, the
conservation of both pattern and process will require two things:
consideration of representation and design in the identification
5454 1 www.pnas.org/cgi/doi/10.1073/pnas.101093498
of potential conservation areas; and sound decisions about the
progressive implementation of conservation action so that land
use and other threats have minimal impact on the desired
outcome.
In the implementation phase of a reserve system designed for
retention and persistence, the importance of threatening pro-
cesses in compromising the achievement of both pattern and
process goals will need to be considered and balanced (12~. This
strategy should achieve greater long-term benefits for biodiver-
sity than strategies based only on the representation of pattern.
Planning for an Evolutionary Future in the CFR
Because conservation planning is a spatial exercise, an essential
requirement of planning for the maintenance of natural pro-
cesses is the identification of the spatial components of those
processes examples are habitat gradients or geographical bar-
riers that are associated with lineage turnover. To our knowl-
edge, no studies have integrated these spatial requirements into
a conservation plan. This we are attempting to do in a current
exercise for the CFR.
On the basis of our present understanding of diversification
processes in the CFR, we identified seven spatial components to
be protected to promote ongoing evolution and set targets for
each (Table 1~. These targets can be used to produce a map of
irreplaceability for evolutionary processes but, in the overall
conservation plan, are combined with requirements for repre-
senting biodiversity pattern and the continuation of various
ecological processes. The next step was to design a system of
conservation areas by selecting from areas that contain one or
more of the spatial components in Table 1. The options associ-
ated with the selection of areas were constrained by several
factors, including a pragmatic requirement to incorporate the
existing reserve system; the avoidance of excessively transformed
areas; and the need to select, where possible, areas also with high
irreplaceability for targets for biodiversity pattern. In many
instances, especially in lowland regions, habitats are so exten-
sively transformed that it is no longer possible to achieve process
targets the evolutionary future of the CFR has already been
severely compromised.
Fig. 2 shows the sequential assembly of the conservation
system designed to achieve evolutionary process targets in the
CFR. The rule applied for the design sequence was to initially
attempt to achieve targets for which there were limited options
Cowling and Pressey
OCR for page 67
Table 1. Spatial components of evolutionary processes in the CFR
Spatial component Method of identification Target Key evolutionary process conserved
Juxtaposed edaphically different Identify planning units with At least one example of each Ecological diversification of plant
habitats particular combinations of Broad specified combination of lineages in relation to fine-scale
Habitat Units (56) that reflect Broad Habitat Units in edaphic gradients (20).
strong edaphic contrasts each major climatic zone.
(limestone and adjacent acidic
substrata) known to be associated
with plant diversification
processes. Exclude"unsuitable"
planning units based on
fragmentation of native
vegetation and lack of contiguity
with other units.
Entire sand movement corridors Identify planning units containing At least one entire corridor Ecological diversification of plant
the three specific dune pioneer of each type. lineages in relation to fine-scale
habitats. Exclude any corridors edaphic gradients (20).
(sediment-sources) with limited
conservation potential of
surrounding land (particularly in
the sediment-sink or downwind
zones). Assume stands of dense
alien plants make corridors
irrecoverable.
Whole riverine corridors Identify major rivers that link inland All of any intact, or the Migration and exchange between
basins with coastal plains. Identify untransformed parts of inland and coastal biotas (42).
untransformed corridors or parts each of the major
of corridors. corridors (five river
systems; ten river
corridors).
Gradients from uplands to Identify planning units on the At least one example of each Ecological diversification of plant
coastal lowlands and interior following interfaces of upland and gradient within each of and animal lineages in relation
basins lowland: the major climate zones to steep environmental gradients
Coastal range/coastal plain (9). Gradients width must (6, 34, 41).
Coastal range/interior basin encompass at least one
Inland range/interior basin untransformed planning
Inland range/Karoo basin unit and maximize climatic
which would allow the heterogeneity.
construction of corridors
between these landscapes.
Macro-scale climatic gradients Complement gradients between Unbroken transects along all Geographical diversification of
lowlands and uplands (mesa scale) of the geographical plant and animal lineages in
with macro-scale connectivity in gradients. relation to macroclimatic
two main directions: gradients(56, 58). - --
North-south in the western CFR ~~ -
along both the coastal - =-~
forelands and inland ~ ~ ° coil
~~''~-.'.,~.~.'~'-~'.
mountains;
East-west in the southern and ; ;-
eastern CFR along coastal - ~-~
forelands, coastal mountains,
interior basins, and interior
mountains.
Mega wilderness areas Identify contiguous planning units One in the northwestern, Maintenance of all evolutionary
that encompass ca 500,000 ha of one in the southern, and processes, including
untransformed habitat, transcend one in the southeastern predator-prey processes
biome boundaries (63), and CFR. involving top predators (59).
include all or part of a riverine
corridor.
Transitions between major Where possible, expand conservation As many transitions as Exchange between
Broad Habitat Unit categories areas to encompass these possible. phylogenetically distinct biotas.
(56) and blame boundaries. transitions.
The components need to be identified geographically and given quantitative targets for conservation planning. The term `'planning units" refers to areas
used in our current planning exercise as the preliminary building blocks of an expanded system of conservation areas. They are 1/16° grid cells each covering
about 4,000 ha. About 2,510 planning units cover the whole CFR.
Cowling and Pressey
PNAS 1 May 8, 2001 1 vol. 98 1 no. 10 1 5455
OCR for page 68
_ Negotiated Reserve
4~ ~ Mandatory Reserve
4 0} F it. ~ I4 1 ~ ~ ,
~ C ~
<~0 ~
AL
~ _ _
HE
GIL
_
01
he
~ m
D
E
, 4'1 F
ClEl ~ ,
; 'I
,) ~ m 181~ ~ ~ ~ ~
AWL
\-~
I ~ H
1. 1
.. ~ ___ L
I?
.
me__
Din
_r
-
Fig. 2. Stages in the design of a system of conservation areas for the CFR that will achieve targets for biodiversity pattern and ecological and evolutionary
processes. (A) juxtaposed edaphically different habitats; (B) entire sand movement corridors; (C) whole riverine corridors; (D) upland-lowland gradients; (E)
macroclimatic gradients; (F) mega wilderness areas; (G) major biological transitions not identified in stages A-F; and (H) an additional minimum set of areas
required to achieve all pattern targets. The minimum set was identified by using a reserve selection algorithm driven by irreplaceability (53).
(e.g., unique combinations of edaphic substrata), proceeding to
targets offering greater flexibility in terms of spatial location.
Particular attention was given to achieving more than one target
within any one notional reserve. Nonetheless, the overall system
depicted in Fig. 2 is one of several options for conserving
processes and is accordingly presented as an example of the
approach that we have used. Areas contributing to process
targets were selected in the C-PLAN software system (53) as
negotiated reserves, whereas the existing reserve system is
depicted as mandatory reserves. The mandatory reserves, how-
ever, do not contribute substantially to achieving process targets.
Of the total area selected to achieve the targets, only 41% was
contributed by the existing reserve system, and the area contri-
bution of this system to each of the seven spatial components
ranged from 0-48%. Thus, in addition to being another example
of an ad hoc reserve system that is inadequate in terms of pattern
representation (ref. 59; see also ref. 51), extant CFR reserves are
not located in a manner that will sustain evolutionary processes.
5456 1 www.pnas.org/cgi/doi/10.1 073/pnas.101 093498
The components identified in Table 1 comprise the spatial
requirements of evolutionary processes at many spatial scales.
The planning units themselves, each comprising about 4,000 ha,
are sufficiently large to sustain regular, whole-patch fires (64), a
disturbance essential for the maintenance of key evolutionary
processes (22), to maintain plant and insect biodiversity (65-67),
and to maintain plant-insect pollinator relations (67, 68~. How-
ever, larger areas of juxtaposed habitat encompassing the spatial
components of evolutionary processes that operate over meso-
and macroscale ecological gradients, are required to ensure the
long-term persistence of biodiversity in the CFR. Accordingly,
we hypothesize that the system identified in Fig. 2 will ensure
ongoing diversification in the CFR by conserving the spatial
components of key evolutionary processes. The maintenance of
juxtaposed habitats over different spatial scales should impart a
measure of resilience to impending climate change (44), which
is predicted to have a substantial effect on the flora and
vegetation of the CFR (69~.
Cowling and Pressey
OCR for page 69
A key issue in conservation planning is the scheduling of
conservation action on the ground, requiring choices in both
space and time (61~. In principle, irreplaceability and vulnera-
bility to threatening processes should guide priorities for imple-
mentation: action should minimize the extent to which conser-
vation targets are compromised before conservation
management is applied (614. However, when conservation tar-
gets deal with the representation of both pattern and process, as
is the case for this study, there are no established ways of
comparing the relative risks of alternative approaches to imple-
mentation. For example, how should the outright loss of an
extensively transformed and fragmented habitat be compared
with the loss of a section of climatic gradient, comprising
adequately conserved habitat but essential for sustaining evo-
lutionary processes? Resolving these conflicts is a major chal-
lenge for conservation planning (12), and is the subject of
ongoing research. A key contribution is the establishment of
irreplaceability maps for the achievement of process targets.
Discussion and Conclusions
The system of conservation areas identified in Fig. 2 represents
a set of hypotheses about the maintenance biodiversity and
ongoing diversification in the CFR. The major prediction is that
this system will maintain more biodiversity in the long term than
alternative systems based on pattern representation only (12~. It
is not feasible, ethically or practically, to test this prediction: the
scale and nature of the problem rule out experiments. We can,
9.
10.
11
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however, monitor and, where possible, adjust the design as
results and more data become available; although, given the
rapid escalation of all components of global change, time is not
on our side (9, 11~.
The contributions of the conservation planning approach that
we have used for the CFR are the spatial identification of
evolutionary drivers and the setting of explicit targets for these
spatial components. Furthermore, in the larger project described
partially here, these considerations are being integrated more
thoroughly than shown in this indicative and preliminary ac-
count. The larger study will also have to face difficult tradeoffs
between the representation of pattern and process, as well as
between requirements for biodiversity conservation and other
socioeconomic considerations. There are no easy answers for
resolving these conflicts, nor can they be ignored.
Finally, the concepts and analytical techniques used in this
study are of general applicability. The big challenge for all
regions is to identify the spatial components of evolutionary
processes and set targets for these. Biodiversity is being lost
everywhere at an alarming rate. The current focus on pattern
representation in conservation planning will only temporarily
slow the rate of extinction. It is vitally important to plan for
evolutionary futures everywhere.
Charlotte Heijnis, Mandy Lombard, and Matt Watts provided technical
assistance. We thank the Global Environment Facility, through a grant
to World Wide Fund: South Africa, for financial assistance.
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PNAS 1 May 8, 2001 1 vol. 98 1 no. 10 1 5457
Representative terms from entire chapter:
conservation planning
