Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 1 – Background & Analysis Process
appears to be no competing land use proposed for them at this time. Also, a very large percentage of this ecosystem type is
already included in existing conservation protected areas such as Kayan-Mentarang National Park.
** The goal for these targets is set higher than recommended for widespread target systems because their current areas
have been greatly reduced in extent in just the last 50 years. The percentages also reflect that we are seeking “viable
occurrences” which already limits the amount that can be captured meeting these criteria given ongoing threats and habitat
degradation.
*** One example of a Major River would be selected for each of the four stratigraphic units.
Priority Setting (Ranking) of Target Ecological System Occurrences
Terrestrial targets
Evaluating and then ranking a group of factors related to actual or potential viability of the
terrestrial conservation target occurrences facilitated setting priorities for these targets. In the
U.S., rankings would normally be generated by Natural Heritage Programs or through expert
advice that would suggest the area required for a viable population of a target species to
persist in, say, Limestone Rainforest occurrences – or the distance between Mangrove
occurrences that would begin to exceed the functional range of the mangrove assemblage of
birds. In East Kalimantan such information is generally lacking. Therefore, we grouped the
value for each occurrence of an ecological system type based on where the value lies in the
quartile distribution of all values for its type across the planning area. This grouping is based
on the logic that the life history strategy of animals in East Kalimantan has evolved to reflect
the habitat patch variability within the region.
Target ecological system occurrences with smaller areas that fell in the lowest quartile could
reasonably be expected to be less able to maintain viable populations of a suite of animals
when compared to larger areas of that same system type that fell into the uppermost quartile.
For example, a Mangrove occurrence that was a long distance from other Mangroves, such
that it fell into the highest quartile for distance between occurrences, could be expected to
have poor migration potential (both in and out) for mangrove birds, insects or primates
compared to occurrences that were closer and fell into lowest (least distant) quartile.
There is some difficulty with this logic when it comes to habitat occurrences that have been
recently fragmented, such as Peat Swamp Forests and the matrix Lowland Rainforest.
However, because the boundaries of these units in this assessment are defined by the
subcatchment areas and not the existing actual patch size, recent incidents of fragmentation
may not bias the statistics as much as might be supposed, except perhaps in the determination
of condition, discussed later in this report.
The occurrence factors considered are as follows:
1). Area
Theory of nature reserve design argues that larger areas are better than smaller ones for the
conservation of biological diversity. But, theories also suggests that several smaller areas of
similar size grouped together within a large single area may, in some circumstances, be a
preferred option, particularly if the risks of frequent burning, contagious disease vectors or
other environmental factors relying on contiguity are high (SLOSS principle). It is unlikely in
the case of Lowland Rainforest ecological dynamics that many disjunct habitat patches
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