Ecoregional Assessment of Biological Diversity in East Kalimantan

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East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems in the southernmost river are much damaged and generally have a Poor or Very Poor viability index. The mangrove forest selected for the portfolio contains the only element of the Kayan River delta found in this Unit and all of that in the Berau River delta. Additionally a small group of coastal mangroves growing directly on limestone substrate in the central northern part of the Sangkulirang peninsula is included to represent this unique ecosystem. All the small islands which have mangroves in the Derawan Island chain (Kepulauan) and Kepulauan Muaras are also included because these mangroves are important structural elements that stabilize these islands and their ecosystems which are so important as rookeries for sea turtles, mostly Green Turtles (Chelonia mydas) and for other small island and fringing reef communities. Stratigraphic Unit 3 - The large patch of mangrove in the Mahakam and Samarinda Bay deltas are well represented in the Portfolio. The Mahakam mangroves are severely degraded in the near-coastal areas by fish and prawn ponds, however, mangroves to the inland side of the Nypa palms, which mark the major brackish water interface, appear to be in reasonable condition and apparently have suffered only opportunistic cutting for firewood. Stratigraphic Unit 4 - Mangrove patches are captured in several places in this small stratigraphic unit – despite being fed by relatively small rivers, they have much potential for providing important habitat for many of the focal species at this southernmost portion of the planning area. The patches of mangrove forest here tend to be more linear – tracking the terminal flow courses of the rivers that feed them perpendicular to the coast rather than parallel as in the former occurrences represented in the portfolio. It remains to be seen whether the effect of this configuration affords these forests more or less susceptibility to the threats of conversion to tambak or cutting for firewood and charcoal purposes. Overall, mangroves in the proposed portfolio of sites are poorly represented in lands having any protected status. In an attempt to not grossly over-represent the East Kalimantan goal for mangrove occurrences, much of the coastal strip mangrove is not well represented. These small coastal mangrove patches, which were possibly contiguous or almost so as recently as the middle of the twentieth century, undoubtedly played an important role in physically stabilizing the East Kalimantan coast as well as being important in the ecological dynamic of the coastal zone. More detailed and timely Conservation Area Planning at a later date may incorporate these smaller coastal patches in conservation initiatives related to the larger delta patches identified in this portfolio. 7
East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems B. Freshwater Swamp Forests Description Freshwater Swamp Forests are found on alluvial soils that are flooded for long periods of time with fresh water. Freshwater swamps are widespread throughout Kalimantan and occupy about 7% of the land surface area (MacKinnon and Artha 1981). They are associated with coastal swamps, inland lakes and huge low-lying river basins. These are associated in East Kalimantan with coastal Peat Swamp Forest near Mangrove Forests from the mouth of the Sesayap River, in the most northern stratigraphic unit, to a distance of approximately 90 km inland. These forests are less acidic and more nutrient rich than either Peat Swamp Forests or Heath Forests. Freshwater Swamps usually have taller trees and are more species rich than Peat Swamp Forests. They are extremely heterogeneous in soils and vegetation, although a few centimeters of peat may occur. This heterogeneity is borne out by the fact that all 10 aggregated RePPProT system types identified in this planning process are present underlying the single Sesayap Freshwater Swamps occurrence. Floristic composition varies from floating grass mats, such as are common in the Mahakam lakes area, to pandan and Palm Swamp, scrub and forest. Prime Freshwater Swamp Forest has trees with an average height of 35m, some lianas and epiphytes. They share many species with lowland dry forests but are generally less rich in taxa. Forest structure is less layered and the trees are smaller and shorter. The most important trees in this type of forest are Campnosperma, Alstonia, Eugenia, Canarium, the tall legume Koompassia, Calophyllum and Melanorrhoea. The swamp Sago palm, Metroxylon sagu, also thrives there (Whitmore 1984). Faunal diversity is usually higher in Freshwater Swamp Forests than in Peat Swamp Forests. There can be good densities of primates in these forests, which are most common along the rivers. The most common primate found in this forest type is the Long-tailed Macaque, Macaca fascicularis. 8
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Ecoregional Assessment of Biological Diversity in East Kalimantan

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