Danau Sentarum National Park is characterized by lakes and a variety of swamp forests that are unique, and unlike comparable habitats in Indonesia or Southeast Asia. Structurally, it was once very similar to the Mahakam Lakes in East Kalimantan, but the latter area is severely degraded. Three main swamp forest types are recognized on the basis of structure: dwarf swamp forest, stunted swamp forest, and tall swamp forest. Within each of these, various vegetation types are recognized on the basis of dominant species. Basic structural types are closely linked with depth and duration of flooding. Aquatic vegetation is virtually absent, due to a combination of severe fluctuation in water levels and low nutrient levels in lake waters. Plant species diversity of each habitat is low, but due to diversity in habitat types, overall plant diversity is relatively high and 262 species are recorded for swamp forests. DSNP harbors 30-40 endemics or restricted range species. The most serious immediate threats to the integrit y of these forests are fires and illegal logging, while swidden cultivation on levees forms the main threat to the riparian habitat.
BACKGROUND
Swamp habitats in Indonesia
Large areas of non-marine swamp occur in the lowlands of Sumatra, Borneo, and Papua, extending over a total area of 23-3 5 million hectares (Euroconsult, 1984; Silvius et al., 1987; RePPProT, 1990; IIED, 1994), and form one of the largest areas of tropical swamp world-wide outside of Amazonia (WCMC, 1992; Maltby, 1997). These swamps consist of two main types, namely peat swamp forest and freshwater swamp forest. The former is characterized by peat soils, which by definition have an organic matter content of at least 65 percent, while the latter occurs on predominantly mineral soils. More than three-quarters of all peat land in Southeast Asia occurs in Indonesia, and with a total area of 17-27 million hectares, it accounts for more than half of the world's total of tropical peat land (Maltby, 1997).
Most of Indonesia's non-marine swamps are near coastal areas and were forested before the advent of large-scale commercial logging in the 1980s and 1990s. Isolated swamps further inland, in the middle or upper basins of larger rivers, are far less common. Papua very extensive swamp forests are broad, inland extensions of coastal freshwater swamp forests, and due to the rugged, mountainous nature of the interior, inland swamps are either absent or consist of medium to high altitude bogs (Paaijmans, 1976; Petocz, 1989). Most swamps of Sumatra follow a similar pattern: peat- and freshwater swamp forests are found along most of the east coast and extend far inland, with wooded medium to high altitude bogs found in the central mountain range (Scholz, 1983; Silvius et al., 1987). Due to a flat topography, lowland swamps have developed far inland on Borneo and are well-developed in the middle-upper reaches of the island's longest rivers, especially along the Mahakam and Kapuas (Silvius et al., 1987). While forested swamps along the Mahakam have largely deteriorated over the past decades, those in the upper...