Ecoregional Assessment of Biological Diversity in East Kalimantan

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East Kalimantan Ecoregional Assessment: Chapter 1 – Background & Analysis Process Viability Index of Target Ecological System Occurrences Terrestrial targets As described above, the viability index for each target system, Lowland Limestone Rainforest for example, was evaluated for the following variables in this ecoregional assessment: area of the occurrence; shape of the occurrence; condition of the forest within the occurrence; and two factors representing the landscape context of the occurrence, namely its isolation and condition of the buffer zone within a 2 km wide zone around the occurrence. Further discussion with ecologists indicated that, for terrestrial system occurrences, these five factors should be weighted because some are more important than others for assessing the viability of a conservation target occurrence. These ecologists suggested that the most important factor was the condition of the forest within an occurrence, followed by (in order of decreasing importance) area of the occurrence, condition of the buffer zone around the occurrence, its isolation, and finally, its shape. Table 1.2 indicates the weighted percentages we utilized to reflect the relative importance of these five factors towards assessing occurrence viability. Table1.2. Reference table to determine viability index loadings (weighting) to apply for the five factors involved in determining the viability index of a target terrestrial ecological system. Factor / Rank loading Very Good Good Poor Very Poor Condition inside 40 30 10 0 Area 30 20 10 0 Condition outside 15 10 5 0 Isolation 10 8 3 0 Shape 5 3 1 0 In the case of Area, Isolation and Shape, the viability ratings for each occurrence are entered as absolute values into the Viability Index database. For example, if an occurrence has a Poor Area rank, Very Good Isolation rank and Good Shape rank then the values that are entered into the viability index database for these factors are obtained from Table 1.2 and are: 10, 10, and 3, respectively, as highlighted in blue above. Condition both inside and outside of a targets occurrence is more complex, and being more important to the determination of viability, should reflect gradations of current condition rather than absolute values. These are calculated as follows: Condition inside- If there is an occurrence with only a single condition, for instance all the forest is in Good condition, then the value inserted into the viability index database is obtained from the above reference Table 1.2; for a value of 30. If there are two areas within an occurrence that are in different condition, for example, one side burned and the other untouched by fire, then the loading from Table 1.2 for each condition is multiplied by the proportion of the occurrence. These two values are then added together and become the value that is entered into the viability database for that occurrence. As an example, in Fig.L, 30% of the occurrence area is ranked as Very Good (loading value 40) and 70% of the area as Good (loading value 30). The rank that is entered into the viability index database for this occurrence is: (40 x 0.30) + (30 x 0.70) = 33. 27
East Kalimantan Ecoregional Assessment: Chapter 1 – Background & Analysis Process Condition outside – This is very similar to the above calculation but the area considered is the area of the 2 km buffer zone around an occurrence, and the loading value from Table 1.2 will be different. As an example, in Figure L, assume that 20% of the buffer area of an occurrence is Poor (Loading value of 5) and 80% of the area is Good (loading value 10). Then the viability rank that is entered into the viability index database for this occurrence is (5 x 0.2) + (10 x 0.8) = 9. Using the above example for a hypothetical occurrence, the viability index would be summed as follows: Factor Viability Rank Condition inside 33 Area 10 Condition outside 9 Isolation 10 Shape 2 Total Rank Score 64 Figure L: Viability Indices of Karst Forest The distribution of the Total Rank score (weighted) for each occurrence in each target ecological system type is again grouped into quartiles. The lowest, 75% Very Good (dark green). The Folio Text in Appendix V, Figure _._ shows a flow chart of the processes involved in calculating the Viability Index of each element occurrence. 28
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Ecoregional Assessment of Biological Diversity in East Kalimantan

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