Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems
because they were adjacent to the Mahakam River and afforded that system some ecological
support from particularly bat pollinators or were grouped inside a proposed protected forest
area.
In stratigraphic unit 4, 59.4% of the occurrences were selected. The two largest of these had
Very Good viability rankings. One was selected because it was in the upper catchment area
of the largest river in this unit, the Kerang River, and the other was chosen because it was the
largest coastal occurrence. A small occurrence with Good viability was included because it is
an important element of the Wain River delta and the Balikpapan Bay ecosystem.
The majority of these occurrences (58%) were in the lowest precipitation zone of < 2000
mm. There were five RePPProT subdivisions that are located in these Lowland Limestone
Rainforests indicating some substrate heterogeneity, although the predominant substrate was
the RePPProT type KPHS: karst plain/hill system followed by SDBS: sand dominated beach
system.
Most of the Limestone Karst Forest occurrences selected for the portfolio were not associated
with the target Major River systems. The exception was an elongate occurrence adjoining the
Mahakam River. Most were selected because they were large occurrences, and/or were
associated with selected Heath Forest, Important Bird Areas and/or protected forest areas.
The largest patches of Lowland Limestone Rainforests are in the Sangkulirang-Mangkalihat
Peninsula and these are well represented in the portfolio. It is clear from the Landscape
Context ratings for Lowland Limestone Rainforest occurrences, that many of them are
buffeted by threats from outside, particularly wildfires and logging, but that the other threats,
while currently minor, have great potential to cause a substantial impact on the quality of the
habitat inside these visually stunning and ecologically critical landscapes.
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