Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems
Conservation issues and threats
• Conversion
Conversion of Freshwater Swamps, particularly for rice cultivation, is the major threat to
this ecosystem. MacKinnon et al. (1996; Table 3.1) reports that the extent of this forest
type in East Kalimantan has shrunk from an original area of 422,000 ha to 195,000 ha in
1996. Much of this conversion has occurred over the last 20 years. Our analysis shows
however that there is, as of 2001, an extent of approximately 350,700 hectares in this
province. This may be a factor of better satellite imagery available today than what was
utilized for McKinnon’s report.
• Logging
These swamps contain trees of high commercial value, so logging is an ongoing threat to
this target ecological system. Commercial forest concessions (HPH in Bahasa Indonesia
acronym) completely cover the single occurrence of this community type.
• Altered Hydrology
The structure and long-term viability of these swamps is threatened by alterations to
water levels in the major river systems and more frequent flooding episodes. This is a
consequence of changes in the hydrology of watersheds concomitant with wholesale land
clearing and targeted clearing of riparian vegetation for agricultural purposes.
• Wildfires
Wildfires over the last decade in East Kalimantan have encouraged dramatic changes in
the floristic composition and structure of Swamp Forests. Fires favor the Paperbark,
Melaleuca cajuputi, a fire resistant, understory tree species with inflammable bark. This
species is found throughout South East Asia and Australia and often forms pure stands as
a fire disclimax community.
Occurrence Unit Determination
Significant Freshwater Swamp forest was identified first using LandSat imagery to locate this
ecological system in the province. The ECA team then consulted with individual experts and
literature sources to verify classification and condition.
Freshwater Swamp Forest occurrences were determined by the secondary water catchment
areas (sub das) to which they belong. Thus, if a sub das contained several patches of such
forest, these were regarded as a single occurrence. This is logical, because Freshwater
Swamp Forests are frequently flushed out by rivers and rely less on rain to sustain their
moisture than do Peat Swamp Forests. Thus all such patches in a sub das likely share a
common hydrologic and nutrient connectivity. Further, they often support a variety of
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