|
|
 |
|||||||||||
|
|
 |
|
|||||||||
|
|
 |
 |
Within this section:
|
|
|
Home Practical Application of Biodiversity Surrogates and Percentage Targets for Conservation in Papua New GuineaComparison with other approaches We have determined that RMUs totaling 10% of the area of PNG could represent a 1172-cluster-level of biodiversity in the absence of any costs or constraints. That hypothetical analysis provides a biodiversity target for real-world planning. Faith et al. (2001a) describes a priority set of areas that achieves this same level of representation in the presence of cost and constraints (a total area of 16.8% of the country and a "timber cost" of 93218 units). It will be useful to contrast this approach with two more conventional ways that a 10% target might have been implemented. In one case, we examine a scenario where protected areas adding up to approximately 10% of the total area are formed from a combination of the existing protected areas, plus gradual additions of new areas that are not in demand for other land uses. We simulate that result by starting with the existing set of protected areas and adding areas with lowest timber volume ratings until the 10% area level is achieved (Figure 6a). Opportunity costs would be low, having used areas not attractive for other land uses, but the total biodiversity representation was only about 80% of the representation target set in the way described above. The country would be credited with achieving its 10% target, but not in fact perform well in actual biodiversity protected in nominated protected areas. Further, the shortfall in other cases could well be greater than the 20% found here. In the second scenario, we examine an approach that directly attempts to address biodiversity representation, but does so inefficiently. We suppose that the pre-defined vegetation types are used as biodiversity indicators, and the target is interpreted as requiring 10% representation of each one of these types (Figure 6b). We find that a set of areas selected to achieve this target only represents about 2/3 of the representation target that was set using the method described above, yet the level of forgone timber volume is more than 100,000 units (compared to 93,218). Targets of 10, 12, or 15%, expressed simply as percentages of total area, continue to be advocated (e.g., Balmford et al. 2000; Howard et al. 2000). Such targets continue to allow protection of the least productive and least threatened landscapes (see also Pressey 1994; Margules and Pressey 2000). Further, these targets are misleading as a basis for making recommendations about the costs of biodiversity representation. Fifteen percent of the total area could be very cheap or very expensive in terms of opportunity costs, yet Balmford et al. (2000), for example, assume that any 15% of total area is equally costly. These difficulties lend support to the argument that standard implementations of 10% targets may not represent biodiversity all that well, and may not appropriately balance other land use opportunities.
|
|
|
|||
|
|
|||||||||||
