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Within this section:
 Introduction
Some recent papers
Biodiversity
Conservation
Phylogenetic
inference
Biological
monitoring
The PNG papers
Some older papers
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Home Research and CollectionsBiodiversity & Systematics
A Biodiversity Conservation Plan for Papua New Guinea Based on Biodiversity Trade-offs Analysis
Opportunity costs
Index of timber volume
A Forest Inventory Mapping (FIM) system (McAlpine and Quigley 1998) evolved from PNGRIS. It was developed to provide information on the type and extent of the forest resource and its use by the forest industry. It is a national coverage at a scale of 1:100,000. Information on forest and non-forest vegetation types, land tenure, timber volumes and other variables is recorded within Forest Mapping Units, or FMUs. FMUs are generally smaller than RMUs and each FMU is coded as one and only one vegetation type. For this study, FMUs were overlain on RMUs and the area of each FMU (i.e., vegetation type) within each RMU was recorded. Not all of the information in FIM is generally available, especially information on timber volumes and proposed timber concessions. However, an index of timber volume was made available for this project by the PNG Forest Authority on a scale from 0 for very low volume to 5 for very high volume. These values were aggregated to the level of the RMUs using a weighted sum of
the FMU values. For example, if an RMU contained FMUs of rank 3 with area of 100 km2, and FMUs of rank 0 with area 50 km2, then the combined RMU value was 3x100 + 0x50 = 300. These values were then log-transformed. The rank values were multiplied by the proportion of the FMU in a given RMU and the resulting values summed over RMUs. This is not an estimate of timber volume per unit area and it means that larger RMUs may have high timber volume estimates, even when timber volume per unit area is low. Figure 1a is a map of timber volume indices. This map corresponds well with Map 1 of the National Forest Plan for Papua New Guinea (PNGFA 1996).
Agricultural potential
This was a simple model proposed by the PNG Department of Agriculture and Livestock. RMUs with slope classes 1- 4 (from less than 2° up to 10-20°) and drainage classes 1 and 2 (well-drained and imperfectly drained) in PNGRIS were designated as having agricultural potential and all other RMUs were designated with none. Figure 1b is the resulting presence/absence map showing the 1525 RMUs with agricultural potential under this simple model. Clearly, there is scope for improving this model, and this should be followed up as part of the implementation of BioRap in PNG. Excluding areas of seasonal inundation and/or developing models for different agricultural products are two examples of how it could be improved. In the analyses, preference was given to the selection of RMUs having low agricultural potential (see later chapter).
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