They fail to take account of spatial heterogeneity and turnover of features from area to area (Howard et al., 1998). Conservation biology is aimed at managing populations in wild through population viability analysis, which tries to predict likely time of extinction under different management regimes (Ludwig, 1999).
Since purpose of priority areas is to minimize biodiversity loss, it is necessary to consider vulnerability and persistence including population viability in conservation planning (Gaston et al., 2002). If areas that are being managed to minimize vulnerability and maximize probability of persistence do not contain adequate biodiversity representation in first place, then biodiversity protection will have failed.
Tools for identifying priority areas fall into two distinct but interdependent classes. One comprises methods for acquiring suitable data sets, and other comprises methods for using those data sets. Considerable effort has been made in improving first class of methods, particularly in computer technology.
Software and associated activities, now available to conservation biologists and planners are tools for compiling better data sets. Examples include MASS (MacKinnon, 1992), BIOCLIM (Busby, 1991) and Conservation International’s RAP (Rapid Assessment of Biodiversity Priority Areas; Abate, 1992).
Significant improvements have been made in display and manipulation of data using Geographic Information Systems (G1S). Methods are now being combined with GIS, so that planning options and negotiations with stakeholders can be explored interactively (Ferrier et al., 2000).
Software widely used for this purpose, C-PLAN, DIVERSITY and WORLDMAP, all link iterative selection procedures and other analyses to GIS tools. Both classes of methods, those for compiling suitable data sets and those for identifying priority areas are necessary but quite different information on vulnerability or threat can be used to help set the goals of priority area selection procedures (Gaston et al., 2002).
Because resources for conservation planning are limited, not all biomes, parts of countries, whole countries, or regions can be dealt with equally or at the same time. In identifying priority area networks, preference should be given to places that are both vulnerable to a threatening process, such as land clearing for agriculture and also make an important contribution to conservation goal.
Alternatively, goal might be to represent species that are vulnerable to threatening processes, rather than all the species in a region, in which case the data set being used would contain only those species.