Environmental Engineering Reference
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(Olson et al., 2001, p. 933). Only in the endemic bird areas approach are
biogeographic units dei ned a posteriori by the distributions of the species
concerned (Stattersi eld et al., 1998). Relative to equal-area grids, biogeo-
graphic units bring advantages of ecological relevance, while megadiver-
sity countries (Mittermeier et al., 1997) bring political relevance.
However, reliance on biogeographic spatial units raises several compli-
cations. Various competing bioregional classii cations are in use (Jepson
and Whittaker, 2002), with the choice of system having considerable
repercussions for resulting conservation priorities (Pressey and Logan,
1994). Further, when unequally sized units are employed, priority may be
biased towards large areas as a consequence of species-area relationships.
Assessment of global conservation priorities should, therefore, factor out
area, either by taking residuals about a best-i t line to a plot of species
against area (Balmford and Long, 1995; Brooks et al., 2002; Werner and
Buszko, 2005; Lamoreux et al., 2006) or by rescaling numbers of endemics
using a power function directly (Veech, 2000; Brummitt and Lughadha,
2003; Hobohm, 2003; Ovadia, 2003). Nevertheless, use of a priori bio-
regional units for global conservation prioritization will be essential until
data of sui cient resolution become available to enable the use of grids.
Spatial patterns
In Figure 2.4, we map the overlay of the global biodiversity conservation
priority systems into geographic space from the conceptual framework
of Figure 2.3. Figure 2.4A illustrates the large degree of overlap between
templates that prioritize highly vulnerable regions of high irreplace-
ability: tropical islands and mountains (including montane Mesoamerica,
the Andes, the Brazilian Atlantic forest, Madagascar, montane Africa,
the Western Ghats of India, Malaysia, Indonesia, the Philippines and
Hawaii), Mediterranean-type systems (including California, central Chile,
coastal South Africa, south-west Australia and the Mediterranean itself),
and a few temperate forests (the Caucasus, the central Asian mountains,
the Himalaya and south-west China). Highly vulnerable regions of lower
irreplaceability (generally, the rest of the northern temperate regions)
are prioritized by fewer approaches. Figure 2.4B shows a large amount
of overlap between templates for regions of low vulnerability but high
irreplaceability, in particular the three major tropical rainforests of
Amazonia, the Congo and New Guinea. Regions of simultaneously lower
vulnerability and irreplaceability, such as the boreal forests of Canada and
Russia, and the deserts of western USA and central Asia are prioritized
less often.
Two general observations are apparent. First, most land (79 per
cent) is highlighted by at least one of the prioritization systems. Second,
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