Hotspots have been qualified as the “silver bullet” approach to conservation, since it targets unique species richness. They also suffer from what Kent Redford has referred to as the “tyranny of the rainforest”. This due mainly on the fact that about two thirds of all species occur in the tropics, largely in tropical humid forests (Raven, 1980, in Pimm and Raven, 2000).
While the hotspots analysis is by itself a ranking exercise (hotspots over non hotspots) it further ranks hotspots utilizing numbers of endemics and endemic species/area ratios for both plant and vertebrates and habitat loss. This exercise which is acknowledged to be for “qualitative purposes in qualitative fashion” (Meyers et al., 2000), conflicts with the way ecoregions are ranked in the representative approach in which only ecoregions or Regional Habitat Units (BSP, 1995) within the same Major Habitat Types are compared to determine their relative importance.
BIODIVERSITY SUPPORT PROGRAM (BSP, 1995)
Regional geographic priorities in this exercise were determined by ranking the Regional Habitat Types within Major Habitat Types, based on the consideration and weighting of biological value and conservation status. Biological value of areas was determined through the definition of priority areas for: plants, insects, birds, herpetofauna, mammals and freshwater fish, the determination of respective taxonomic priority areas and their integration into biological priority areas. Conservation status was obtained from landscape-level features that included: presence/absence of large blocks of original habitat; percent of remaining original habitat; rate of conversion; degree of degradation and fragmentation, and; degree of protection. (BSP, 1995)
The scale of the analysis is region-wide and thus is inappropriate to be used in making investment recommendations on a smaller subregional scale or country level. It also excludes marine, freshwater and mangrove ecosystems which limits its recommendations to terrestrial priorities. (BSP, 1995). Furthermore it lacks data-driven rigor and necessarily reflects the unavoidably bias of the experts that were able to attend to the workshop.
Nevertheless the list resulting from this exercise contains a number of areas that have not received significant conservation attention in the past such as temperate forest (Mexico pine-oak and southern Chile, xeric (Caatinga in Brazil, Mexican xerics) and dry forests (Chaco Argentina, Paraguay and Bolivia and Cerrado of Brazil), which were determined of high priority for biodiversity conservation at the regional level.
THE WORLD BANK (Dinerstein et al., 1995).
This priority setting exercise (as well as the BSP and Global 200 that use the representative approach) elevates as a first principle, maintaining the representation of all ecosystem and habitat types in regional investment portfolios. Second it recognizes landscape-level features as an essential guide for effective conservation planning. This assessment integrates two distinct data layers: biological distinctiveness and conservation status. The biological distinctiveness of the ecoregions was assessed based on species richness, endemism, beta diversity, biological phenomena and relative rarity of habitat type. The conservation status was evaluated using the same parameters that were used in the BSP exercise (snapshot conservation assessment), but were further modified to final status after considering potential threats over the next 20 years to ecoregions based on their type, timeframe, spatial scale and intensity. (Dinerstein et al., 1995)
Of all four terrestrial priority setting exercises analyzed, this one is the most geographically detailed, since it was the only one developed at the ecoregion level (although the scale of the published map makes it difficult to use). An ecoregion is defined as a geographically distinct assemblage of natural communities that share a large majority of their species, ecological dynamics and similar environmental conditions and whose ecological interactions are critical for their long term persistence (Dinerstein et al., 1995).