Lee Kong Chian Natural History Museum

Nee Soon Swamp Forest


Found in the southeast of Seletar Reservoir in the Central Catchment Nature Reserve (CCNR), the Nee Soon Swamp Forest (NSSF) is the only substantial primary freshwater swamp forest remaining in Singapore Island. Other areas which used to have freshwater swamp forest habitats but were converted for other land uses include Jurong, Mandai and Pulau Tekong. With an estimated area of about 87 ha (some areas have experienced varying degrees of dicturbances in the past), the NSSF covers the lower areas of a few shallow valleys with slow-flowing streams that drain towards the Seletar River. In between the valleys are higher grounds with dryland forests.

As a result of periodic to semi- permanent flooding, a shallow layer of peat covers most of the ground of this place where the soils are water-logged, anaerobic and unstable. The water here is slightly more acidic (pH <5.5) and flows slower than forest streams. Though clear, the water is stained in a dark-tea colour due to tannins leaching out from decomposing plant matter.

The structure of the forest is rather varied, with patches of dryland forest plant species as well as flooded patches which are dominated by trees with stilt roots, plank-like buttresses and pneumatophores to adapt to flooding and unstable soils, such as Xylopia fusca and Palaquium xanthochymum. Furthermore, almost a third of Singapore's recorded vascular plants (more than 700 species) occur here in NSSF. Among them, some of the plants occur nowhere else in Singapore, including the Singapore Kopsia (Kopsia singapurensis) and the orchid (Bulbophyllum macranthum).

Approximately 16% of Singapore's fauna are found only or mainly in the Nee Soon Swamp Forest. The forest also supports the highest diversity of native freshwater organisms in Singapore, with 48% of Singapore's freshwater fishes, 71% of the amphibians, 47% of the freshwater prawns, and 57% of the freshwater crabs. Some examples include the Dwarf Bumblebee Catfish (Parakysis longirostris), the Masked Swamp Frog (Limnonectes paramacrodon), the Torrent Prawn (Macrobrachium platycheles), the critically endangered dragonfly Potbelly Elf (Risiophlebia dohrni), and the endangered Spotted Eel-loach (Pangio muraeniformis).

The Nee Soon Swamp Forest is unique because it houses endemic species found nowhere else in Singapore and the world. Among these is the swamp forest crab (Parathelphusa reticulata) which is currently found only in a small patch of the forest. The crab species was described in 1990 and has one of the smallest distribution among all crab species. NSSF is also the place where the endemic subspecies of the Cream-coloured Giant Squirrel (Ratufa affinis affinis) was last sighted in the year 1995. Feared to have become extinct locally, this species is one of the largest squirrels around the region and was named by Sir Stamford Raffles in 1821.

Being part of the CCNR, the forest is protected by the National Parks Board. It is also kept pristine thus far due to the presence of firing ranges and firing buffer zones under the Ministry of Defence that restrict human access. Though NSSF is a refuge for many rare organisms and is high in conservation value, this last remnant of freshwater swamp forest in Singapore is particularly of concern due to its small size and the fact that it is highly sensitive to disturbances. If this place is lost, many species would become nationally or even globally extinct.


Lim, K. K. P., D. C. J. Yeo & P. K. L. Ng, 2011. Nee Soon Swamp Forest. Pp. 54-55. In: Ng, P. K. L., R. T. Corlett & H. T. W. Tan (editors), Singapore Biodiversity. An Encyclopedia of the Natural Environment and Sustainable Development, Editions Didier Millet, Singapore, 552 pp.

Yeo, D. C. J., L. K. Wang & K. K. P. Lim, 2010. Private Lives: an Exposé of Singapore's Freshwaters, Raffles Museum of Biodiversity Research, National University of Singapore, Singapore, 240 pp.

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