Ecoregional Assessment of Biological Diversity in East Kalimantan

East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems
with dominants up to 40 meters, which are commonly buttressed. Common species are:
Hopea andersonii, H. dasyrachis and Shorea multiflora and also the non-dipterocarp species
Brownlowia glabrata and Palaquium sericeum. Shrub layer is sparse, with woody climbers
and epiphytes sparse or rare (Anderson and Chai 1982). In East Kalimantan, they almost
always are found on the RePPProT land system type OKI (steep sloping limestone outcrops),
but occasionally also on KPR (rolling hills with highly fractured karst).
Surveys by KPSL-UNLAM (group from University of Lambung Mankurat) in Sangkulirang
Peninsula, East Kalimantan, found no vertebrate fauna restricted to karst country, but have
fauna typically found in the surrounding lowland forest matrix. These include Banteng,
Orangutan, Bornean Gibbon, Sambar deer, Muntjak deer, and Mouse Deer. MacKinnon et
al. (1996) reports that the Serow, Capricornis sumatraensis, an agile goat-like animal may
also be present in these hills and states that pockets of endemic invertebrates are also likely to
occur there. Derek Holmes (in MacKinnon et al. 1996: 311) considered that the Karst Forest
supports an interesting and unusual semi-montane bird fauna, even though the area is lower
than 200 meters and the highest summits reach only 600 meters. Leo Salas (pers. comm.
2003) a tropical forest ecologist working in the region, reports that Pigtail Macaques and
Silver Langurs occupy the cliff walls of the extensive karst occurrences in the Sangkulirang
area, exhibiting unique mountain-climbing abilities and utilizing caves as shelters.
New surveys completed in November 2004 discovered several newly described species of
invertebrates and one new fish species limited in distribution to the caves of the Sangkulirang
Peninsula (Scott Stanley, pers. comm.) This discovery represents the incredible value of this
landform/forest system type to the biological diversity and ecology of the Borneo landmass.
Much remains to be explored throughout this island and it should not be surprising that more
endemic, newly described species will be found.
The karst forest is characterized by the presence of caves, generally infrequently encountered
elsewhere in East Kalimantan. These caves have their own assemblage of vertebrate and
invertebrate fauna that is yet to be fully explored. Recent cave survey expeditions by TNC in
July/August 2004 have found at least 22 species of bats in this area (S. Stanley, pers.comm).
Such cavernicolous bat species are likely to include Megachiroptera that are important
pollinators of many tropical tree species and important dispersers of their seeds. Such fruit
bat species are known to travel distances of up to 80 km a night to feeding areas (Stuart and
Marshall 1976); hence the importance of these caves to the ecology of the surrounding karst
forest and surrounding lowland forest cannot be underestimated. These fruit bats may also
represent a crucial component for some of the more economically important fruit species
such as the highly sought after Durian fruit (Artocarpus heterophyllus). The caves of this
area have also been the focus of French anthropologists who have discovered globally
significant human cultural artifacts, wall paintings, and indications of occupation over
several millennia (Fagé and Chazine, 2001)
Scattered ranges of limestone hills, large boulders and outcrops are scattered throughout
Borneo. However, the Karst country of the Mangkalihat Ranges in the Sangkulirang
Peninsula is the most extensive in Southeast Asia outside Irian Jaya (now Papua). Anon
(1979) considered that the extensive karst landscapes comprising the Mangkalihat Peninsula
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