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HomeResearch and CollectionsBiodiversity & Systematics

A Biodiversity Conservation Plan for Papua New Guinea Based on Biodiversity Trade-offs Analysis

Results

The Current Best Set of Biodiversity Priority Areas
A set of biodiversity priority areas, which meets the 10%-based target and satisfies the objectives of minimising foregone opportunity costs, while avoiding areas of high land use intensity and high population density, including existing protected areas and preferring CNA high priority areas, is shown in Figure 2a. While this level of biodiversity representation could be achieved in our baseline analysis using only 10% of the country, achieving this same goal given costs, constraints and preferences meant that approximately 16.8% of the country was required. The summary properties for this set are listed in Table 2.

Timber volume
Biodiversity priority areas will inevitably be subject to review and re-evaluation over time, to incorporate new knowledge on biodiversity as it is accumulated and to take account of changing economic and social conditions. These planning methods are designed to function as an aid to the conservation decision-making process in an ongoing way. The data sets should be updated and the analyses run again at regular intervals.

One example of such a re-analysis would be the search for substitute areas for those originally selected, but later assessed as inappropriate for biodiversity protection because they have been logged over (see below). The procedure is to delete a nominated area and then use TARGET to search for one or more replacements. We carried out an initial search for substitutes for any of the areas that were in the set but had high timber volume ratings. In summary, area 2384 in the original selected set had a timber index value of 1890. Substitute areas 2410 and 2452 together contribute the same features to the biodiversity goal, but have timber index values of 702 and 3.2 respectively. The new set of 398 areas had a total timber value cost of 93,218 units as opposed to the original 94,403 units (these results are reflected in Table 2 and Figure 2). Nix et al. (2000) further discuss how the methods can be used to identify different solutions depending on the emphasis placed on different attributes and different goals.

Figure 2b highlights the low degree of overlap of these biodiversity priority areas with areas having high potential for timber production, as estimated using the timber volume index map. The analysis identified a set of biodiversity priority areas that not only achieved the target level of biodiversity representation but also minimized the implied forgone forestry opportunities.

Many of the priority areas that do overlap with high timber volume areas are those that were determined to be essential (discussed below). These areas would have to be in any priority set that achieves the biodiversity target, consequently they would be selected no matter what their assessed timber volume. Other current priority areas may have substitutes that could be selected instead. However, because TARGET has tried to find the solution having least opportunity cost, in most cases the substitute area (or areas) would be expected to have a higher opportunity cost. An example of a successful substitution is described below.

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Agricultural potential
The map in Figure 2c highlights the low degree of overlap of the biodiversity priority set with the areas having agricultural potential. While agricultural potential was not used as an "opportunity cost" in the TARGET analyses, some preference was given to the selection of priority areas with low potential. The total number of RMUs having an agricultural potential rating according to our simple index is 1510. Only 110 of these RMUs are within the priority set.

Conservation needs assessment areas
Figure 2d illustrates the high degree of representation of the CNA priority 1 areas by the current best set of priority areas. This is not an unexpected result, since RMUs coinciding with CNA priority areas were preferred to RMUs, which did not fall within CNA priority areas. Only the CNA priority 1 area in the West Sepik does not appear to overlap with the biodiversity priority set. However, areas from the biodiversity priority set do occur in the Toricelli Range and on the Sepik River floodplain, to the immediate north and south of this CNA area. The degree to which the set of priority areas represents an effective refinement of the CNA process is also revealed by examining the extent to which they overlap the individual "hotspot" areas designated by taxonomic experts as part of the CNA study. Table 3, based on data from Beehler (1993), summarises the very high representation, in the current best set of priority areas, of the key biodiversity areas identified by experts in CNA study.

An alternative was to use the CNA areas as an independent test of our biodiversity surrogates. A weak test could be made by not including them in the TARGET analysis, and overlaying the selected set of priority areas to see how well they coincided with a set of areas chosen by experts for their conservation value. However, this was rejected as it would have meant excluding potentially valuable information on biodiversity held by experts, from our analysis. While the current analysis demonstrates how all available information can be used, including expert opinion, a separate re-analysis has been carried out to evaluate correspondence between our surrogates and the CNA areas (Faith et al. 2001b).

Representation of rare species
The representation of at least one area known to contain each of 11 rare and threatened species was included in the biodiversity target. The representation of Queen Alexandra's Birdwing Butterfly, Ornithoptera alexandrae, is shown in Figure 3, as an example. The overall geographic spread of this species was, perhaps fortuitously, well represented in the priority area set.

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