Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 1 – Background & Analysis Process
Selection of Stratigraphic Units
Using both of the previous definitions for landscapes, it is apparent that the physiography of
East Kalimantan is dominated by major river systems and their catchment areas. It is also
noted that these major river basins, their component ecological systems and their
subdivisions, tend to be repeated throughout the Province. It could then be argued that, at the
provincial scale, most of East Kalimantan is a combination of very similar landscapes, each
dominated and ecologically integrated by a major river system.
In the north and central
regions these river systems
are fed by upper catchment
areas in the long north-tosouth
Iban Range bordering
Serawak and Mt. Belayan
to the north of the middle
Mahakam area. The
complexity of the
landscapes has also been
molded differently to some
extent by the Pleistocene
drainage patterns, which
dominate the middle
Mahakam area and its
vicinity. Further, the
limestone areas of the
Sangkulirang/ Mangkalihat
Peninsula also exert a great
influence on that area.
There are also major east to
west trends in climate as
evidenced by rainfall
patterns (Figure J) and
physiography.
Figure H: Major River Systems of East Kalimantan
To capture this
heterogeneity, the East
Kalimantan planning area
was divided into four
stratigraphic units (Fig.I),
which are an aggregate of
the major water catchment
areas. The boundaries of these watershed aggregates define the four stratigraphic unit
polygons. Because of this, these units also capture the major east to west trends in climate
within their boundaries. They are generally described north to south as follows:
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