Environmental Engineering Reference
In-Depth Information
Mittermeier et al., 2003b; Hoekstra et al., 2005). Species-area relation-
ships provide justii cation that habitat loss translates into biodiversity loss
(Pimm et al., 1995; Brooks et al., 2002). However, use of habitat loss as a
measure of vulnerability has several problems, in that it is dii cult to assess
using remote sensing for xeric and aquatic systems, does not incorporate
threats such as invasive species and hunting pressure and is retrospective
rather than predictive (Wilson et al., 2005). The frontier forests approach
(Bryant et al., 1997) uses absolute forest cover as a measure, although this
has been criticized as not rel ective of vulnerability
(Innes and Er, 2002).
Beyond habitat loss, land tenure, measured as protected area coverage,
has also been incorporated into two approaches (Olson and Dinerstein,
1998; Hoekstra et al., 2005). Other possible surrogates not classii ed by
Wilson et al. (2005) include human population growth and density, which
are widely thought to be relevant (Sisk et al., 1994; Cincotta et al., 2000;
O'Connor et al., 2003; Shi et al., 2005; Veech, 2003; Balmford et al.,
2001), and were integral to two of the systems (Sanderson et al., 2002;
Mittermeier et al., 2003b). None of the global conservation prioritiza-
tion templates used threatened species or expert opinion as measures of
vulnerability. Household dynamics (Liu et al., 2003) and political and
institutional capacity and governance (O'Connor et al., 2003; Smith et
al., 2003) af ect biodiversity indirectly, but have not been incorporated to
date. This is true for climate change as well, which is worrying given that
its impact is likely to be severe (Parmesan and Yohe, 2003; Thomas et al.,
2004; McClean et al., 2006). Finally, while costs of conservation generally
increase with threat, no proposals for global biodiversity conservation
priority have yet incorporated costs directly, despite the availability of
techniques to do this at regional scales (Moran et al., 1997; Wilson et al.,
2006). Two of the templates of global conservation prioritization do not
incorporate vulnerability (WWF and IUCN, 1994-97; Mittermeier et al.,
1997) and the remaining two only incorporate it peripherally (Olson and
Dinerstein, 1998; Stattersi eld et al., 1998).
Spatial units
The spatial units most commonly used in systematic conservation planning
are equal-area grids. However, data limitations have precluded their use
in the development of actual templates of global biodiversity conservation
priority to date. Instead, all proposals, with the exception of megadiver-
sity countries (Mittermeier et al., 1997), are based on biogeographic units.
Typically, these units are dei ned a priori by specialist perception of the
distribution of biodiversity. For example, 'ecoregions', one of the most
commonly used such classii cations, are 'relatively large units of land
containing a distinct assemblage of natural communities and species'
