Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems
The selected occurrences attempt to attain the 60% goal of representation in each
stratigraphic unit, in each RePPProT subdivision of this forest type (N = 5), and in each of
the three precipitation zones where they occur (See above Table A). Deviations from these
goals result from the preferential selection of element occurrences that have a Very Good or
Good viability index.
The extent of Heath Forest varied greatly in each stratigraphic unit, with 73% of the total
area occurring in Unit 2. The goal of 60% could be met throughout the portfolio because
most of these occurrences had a high viability rating. Most were relatively large units, not
particularly irregular in shape and all were in good condition having avoided the wild fires of
1983/1984 and 1997/1998, and having soils largely unsuited to conversion for agricultural
purposes. Until recently they were seldom cut and few people live in the vicinity.
Several of the Heath Forest occurrences were physically connected with other key element
occurrences of other targets. For example, a large coastal area of Heath Forest was linked by
‘stepping stones’ of Heath with the selected Peat Swamp Forest around the mouth and
brackish waters of the Berau River. The southern part of the body of these coastal
occurrences was included in the portfolio, as well as the small ‘stepping stones’ with Good
viability rankings.
Some of these occurrences were rated as having Poor and Very Poor viability- even though
they were in Very Good condition inside their elements. Their low rating was based on their
small size, relative isolation and, in one occurrence, its irregular shape. Another was
conjoined with the Malinau River, a small branch of the Segah River; the larger element with
Good viability was included.
Two other areas in stratigraphic units 1 and 2 were closely positioned to the Lower Montane/
Montane Rainforest system occurrences already selected. These were also included in the
portfolio as important watersheds for one of the target Major Rivers (Kinjau River) as well as
being located within an Important Bird Area. These two occurrences were also included in
the portfolio because their viability was considered as Good and Very Good, respectively.
The large, irregularly shaped occurrences immediately to the east of the Malinau River
occurrence are isolated from the other target ecological systems selected for the portfolio,
although they are close to an isolated occurrence of Lowland Limestone Rainforest and fall
within a restricted forest (hutan lindung). One element occurrence is grouped with these two
isolated Limestone occurrences to form a portfolio grouping which is unrelated to a target
Major River.
The small cluster of occurrences on the Sangkulirang Peninsula had low viability rankings
(even though their current internal condition was Very Good) and therefore was not included
in the portfolio.
20