114
The shaping of the global protected area estate
While providing a general model and methodology
for determining ecoregions, the particular data layers
are not available for all parts of the world and, in any
event, the goals of WWF varied somewhat from the
original land - management oriented schemes. It was
therefore necessary to modify the approach to generate
regional ecoregional schemes that, when combined,
would provide a global WWF Ecoregional framework
(Olson et al ., 2001 ).
The Bailey/Omernik ecoregions were delimited
based on a controlling factors methodology (i.e. by
using the factors believed to control ecosystem boundaries as the proxies for their delimitation). However, an
ecoregion as defi ned in the WWF Ecoregions framework is ‘ a large area of land or water that contains a
geographically distinct assemblage of natural communities that:
a share a large majority of their species and ecological
dynamics;
b share similar environmental conditions, and;
c interact ecologically in ways that are critical for their
long - term persistence. ’ (see www.worldwildlife.org/
science/ecoregions/item1847.html )
In practice, the most expedient approach to determining these areas was to amalgamate available
regional and national habitat and distribution maps,
using expert review to refi ne the outcomes. Hence,
Omernik ’ s ecoregions were adopted for North America,
a number of pre - existing schemes were used in the
Latin American review, and in the Asian - Pacifi c region
(including Indonesia), MacKinnon ’ s biounits (above)
were combined with existing forest cover maps as the
start point in the identifi cation of ecoregional units
(Figure 5.7 ).
The upshot is that while the various regional reviews
strive for consistency of approach and end result – a
hierarchy based on habitat types in which an ecoregion is a recognizable ecosystem of regional extent
(Dinerstein et al ., 1995 ) – they necessarily have adopted
slightly different routes, data sources and criteria to
determine their units (Olson et al ., 2001 ; Jepson &
Whittaker, 2002b ). The emergent outcome globally is
that the ecoregions in the WWF scheme represent the
intersection of various pre - existing and novel biogeographical regional frameworks and major ecosystem
type analyses to generate a new synthesis that recognizes the biogeographical distinctiveness of the same
major ecosystem type in different areas of the world
(Olson & Dinserstein, 1998 ; Wikramanayake et al .,
2001 ). Thus, while being predominantly a zonal
could accommodate all WWF international and
national programmes, and it was already being used
(e.g. by TNC) to guide US strategy. It thus had both
established scientifi c credentials and the potential for
multi - agency support internationally, particularly
given its resonance with the human livelihood and
development criteria that were increasingly being
attached to biodiversity funding following the 1992
Rio conference. As a zonal approach, it also had the
virtue of being distinct from, and complementary to,
the CI hotspots scheme.
Having fi rst established the units, i.e. the WWF
Ecoregions, the overall aims of ecoregion - based conservation were stated to be to pursue a ‘ two - pronged
strategy of establishing protected areas and achieving
sustainable management of the lands and waters
outside protected areas ’ (Ricketts et al ., 1999 ).
As discussed in Chapter 4 , the approach of classifying terrestrial habitats into functional ecological units
was developed by R.G. Bailey (e.g. 1996 ) and J.M.
Omernik (e.g. 1987 ) with the purposes of optimizing
land - management goals within North America.
Ecoregions sensu Bailey (1996) are delineated at three
main levels. In the top tier are the domains, four ecoclimatic zones (humid tropical, humid temperate,
polar, and dry) obtained by simple overlay of global
thermal and moisture patterns.
These domains were subdivided again on the basis
of climatic data into 31 second tier ecoregions or
divisions. Bailey ’ s divisional system also distinguishes
between zonal and azonal ecoregions. Azonal ecoregions are, for example, wetlands or alpine ecosystems
that can occur in any zone where the appropriate geomorphology occurs (e.g. the zonal ‘ Icecap Division ’ is
matched by the azonal ‘ Icecap regime Mountains ’ ).
The third principal tier recognized landform as a
key determinant, together with maps of potential
vegetation, to refl ect the limits of recognizable meso -
ecosystems (Bailey, 1996 ). These landscape mosaics
may be further subdivided into smaller micro -
ecosystems based on edaphic factors. Omernik ’ s system
is broadly similar, with the same delineators used at the
macroscale to produce level II ecoregions and level III
ecoregional divisions informed by land - use pattern,
edaphic data and vegetation maps (Omernik, 1987 ).
While each scheme is built upon pre - existing data
layers, the decision criteria for combining these data
are subjective and the extent to which the resulting
units accurately refl ect ecological boundaries and transition zones varies (Chapter 4 ).
The shaping of the global protected area estate
While providing a general model and methodology
for determining ecoregions, the particular data layers
are not available for all parts of the world and, in any
event, the goals of WWF varied somewhat from the
original land - management oriented schemes. It was
therefore necessary to modify the approach to generate
regional ecoregional schemes that, when combined,
would provide a global WWF Ecoregional framework
(Olson et al ., 2001 ).
The Bailey/Omernik ecoregions were delimited
based on a controlling factors methodology (i.e. by
using the factors believed to control ecosystem boundaries as the proxies for their delimitation). However, an
ecoregion as defi ned in the WWF Ecoregions framework is ‘ a large area of land or water that contains a
geographically distinct assemblage of natural communities that:
a share a large majority of their species and ecological
dynamics;
b share similar environmental conditions, and;
c interact ecologically in ways that are critical for their
long - term persistence. ’ (see www.worldwildlife.org/
science/ecoregions/item1847.html )
In practice, the most expedient approach to determining these areas was to amalgamate available
regional and national habitat and distribution maps,
using expert review to refi ne the outcomes. Hence,
Omernik ’ s ecoregions were adopted for North America,
a number of pre - existing schemes were used in the
Latin American review, and in the Asian - Pacifi c region
(including Indonesia), MacKinnon ’ s biounits (above)
were combined with existing forest cover maps as the
start point in the identifi cation of ecoregional units
(Figure 5.7 ).
The upshot is that while the various regional reviews
strive for consistency of approach and end result – a
hierarchy based on habitat types in which an ecoregion is a recognizable ecosystem of regional extent
(Dinerstein et al ., 1995 ) – they necessarily have adopted
slightly different routes, data sources and criteria to
determine their units (Olson et al ., 2001 ; Jepson &
Whittaker, 2002b ). The emergent outcome globally is
that the ecoregions in the WWF scheme represent the
intersection of various pre - existing and novel biogeographical regional frameworks and major ecosystem
type analyses to generate a new synthesis that recognizes the biogeographical distinctiveness of the same
major ecosystem type in different areas of the world
(Olson & Dinserstein, 1998 ; Wikramanayake et al .,
2001 ). Thus, while being predominantly a zonal
could accommodate all WWF international and
national programmes, and it was already being used
(e.g. by TNC) to guide US strategy. It thus had both
established scientifi c credentials and the potential for
multi - agency support internationally, particularly
given its resonance with the human livelihood and
development criteria that were increasingly being
attached to biodiversity funding following the 1992
Rio conference. As a zonal approach, it also had the
virtue of being distinct from, and complementary to,
the CI hotspots scheme.
Having fi rst established the units, i.e. the WWF
Ecoregions, the overall aims of ecoregion - based conservation were stated to be to pursue a ‘ two - pronged
strategy of establishing protected areas and achieving
sustainable management of the lands and waters
outside protected areas ’ (Ricketts et al ., 1999 ).
As discussed in Chapter 4 , the approach of classifying terrestrial habitats into functional ecological units
was developed by R.G. Bailey (e.g. 1996 ) and J.M.
Omernik (e.g. 1987 ) with the purposes of optimizing
land - management goals within North America.
Ecoregions sensu Bailey (1996) are delineated at three
main levels. In the top tier are the domains, four ecoclimatic zones (humid tropical, humid temperate,
polar, and dry) obtained by simple overlay of global
thermal and moisture patterns.
These domains were subdivided again on the basis
of climatic data into 31 second tier ecoregions or
divisions. Bailey ’ s divisional system also distinguishes
between zonal and azonal ecoregions. Azonal ecoregions are, for example, wetlands or alpine ecosystems
that can occur in any zone where the appropriate geomorphology occurs (e.g. the zonal ‘ Icecap Division ’ is
matched by the azonal ‘ Icecap regime Mountains ’ ).
The third principal tier recognized landform as a
key determinant, together with maps of potential
vegetation, to refl ect the limits of recognizable meso -
ecosystems (Bailey, 1996 ). These landscape mosaics
may be further subdivided into smaller micro -
ecosystems based on edaphic factors. Omernik ’ s system
is broadly similar, with the same delineators used at the
macroscale to produce level II ecoregions and level III
ecoregional divisions informed by land - use pattern,
edaphic data and vegetation maps (Omernik, 1987 ).
While each scheme is built upon pre - existing data
layers, the decision criteria for combining these data
are subjective and the extent to which the resulting
units accurately refl ect ecological boundaries and transition zones varies (Chapter 4 ).