Central Catchment Nature Reserve: Green gems

The Central Catchment Nature Reserve has diverse plant and animal species, some unique to Singapore
Lea Wee Straits Times 2 Jun 13;

The largest of four nature reserves here, the Central Catchment Nature Reserve is home to ancient forest trees, crystal-clear freshwater streams and cooling freshwater swamp forests.

The forested area, covering more than 2,000ha, supports a rich variety of plant and animal species, some of which are found only in Singapore.

It is no wonder then that when news broke earlier this year that a proposed MRT line might run through the reserve, nature lovers expressed dismay.

The Land Transport Authority (LTA) clarified in a letter to the Straits Times Forum on Friday that the detailed alignment of the proposed Cross Island Line has not been decided and that it will carry out detailed studies first.

Less than 0.5 per cent of Singapore's original forests remain and they are almost entirely found at the Central Catchment Nature Reserve and Bukit Timah Nature Reserve, which together make up the Central Nature Reserve. These undisturbed primary forests have been called the green lungs of Singapore, as they remove the undesirable greenhouse gas, carbon dioxide, from the air and replace it with life-giving oxygen.

Primary forests are known for their extremely high species richness, said Dr Shawn Lum, president of Nature Society (Singapore) and a lecturer in plant biology at the National Institute of Education.

More than 2,000 plant species have been recorded from Singapore and more than 80 per cent are found in the primary forests, he said.

Protected by the continuous canopy of the primary forests, plant and animal species thrive in the network of freshwater streams and swamp forests at the Central Nature Reserve.

Such a network of streams and swamps is found only at this reserve and nowhere else in Singapore, said Mr Tony O'Dempsey, who holds a bachelor in applied science (surveying) and is a member of the society. The network is especially extensive at the Central Catchment Nature Reserve, which houses the 87ha Nee Soon freshwater swamp forest, the largest of its kind here.

Freshwater swamp forests are unique habitats, and plant and animal species have evolved in ways adapted tothe oxygen-poor and water-logged conditions. For instance, some plants have stilt roots to keep them stable on soft ground while others have pneumatophoric roots which pop up above ground to allow them to "breathe".

Freshwater swamp forests also act as filters to trap silt and sediments from freshwater streams before they flow into reservoirs, said Dr Leong Tzi Ming, a zoologist and author of the book, Our Fragile Rainforest.

There are four reservoirs at the Central Catchment Nature Reserve - MacRitchie, Upper and Lower Peirce Reservoirs and Upper Seletar Reservoir.


The nature group, Cicada Tree Eco-Place, will be organising free public walks through MacRitchie forest trails from this month onwards. Those interested can e-mail contact@cicadatree.org.sg

Spotted tree frog

(Nyctixalus pictus)

Unlike other frogs which breed in ponds, this colourful frog species breeds in pools of water found in the tree holes of mature forest trees. Its slow-growing tadpoles thrive on the organic debris.

It is one of 25 native frog species which have been recorded in Singapore, mostly from the Central Nature Reserve. Two species were first officially described in Singapore.

The Giant Hawker

(Tetracanthagyna plagiata)

The world's largest dragonfly, it has a wingspan of 15cm, as long as an outstretched adult hand.

It likes to hover over streams, hunting flies and other prey. Its larvae feed on small fish and shrimps, and has the unusual habit of feeding on land rather than underwater.

So far, it can be found only at freshwater streams at the Central Catchment Nature Reserve, probably because of the more extensive network of such streams there. Its presence is a good indicator of the health of a freshwater stream.

There are more than 100 species of dragonflies and damselflies in Singapore, most of which are found only in the Central Nature Reserve. Nine species were first officially described in Singapore.

Meranti Nemesu

(Shorea pauciflora)

The Meranti Nemesu belongs to the dipterocarp family, the most dominant group of trees found in primary forests here and the region. They tower above the surrounding canopy, soaring above the other trees in the forest, easily reaching 40m and higher.

They take centuries to regenerate and their average age is 200 to 400 years old.

Unlike the coastal hill dipterocarps found at the Bukit Timah Nature Reserve, the ones at the Central Catchment Nature Reserve are lowland dipterocarps, which are less common here. They are greatly threatened in the region because they are more vulnerable to logging and conversion to oil palm and other plantation agriculture.

The richest and largest remaining pockets of lowland dipterocarp forest in Singapore, and possibly the surrounding Riau island region, are found at MacRitchie. A small patch of Shorea curtisii, which is known to be a coastal hill dipterocarp and is found on Bukit Timah, can also be found here. These are believed to be relics from over 10,000 years ago, when the sea level was lower and the area was a hill. This patch of Shorea curtisii is considered by foresters to be one of the most remarkable parts of the island’s nature reserves.

Tongkat Ali

(Eurycoma longifolia)

This unassuming- looking small tree has been said to have various medicinal properties, but the most well-known one - which has been scientifically proven - is to enhance sexual performance.

It is found only in primary forest and mature secondary forest. It forms part of the understorey of the forest, which include shrubs, herbs and the forest floor. The understorey is where decomposers such as fungi and termites are busy at work, breaking down dead leaves and branches so that these can be returned to the soil and taken up by the plants. It is nature's way of providing fertiliser for the forest.

Chilli Padi Crab

(Geosesarma peraccae)

This 3cm-long crab derived its name from its fiery red colour.

Unlike other freshwater crabs which scavenge for food in the water, it climbs trees regularly in search of vegetative scraps.

It is found only in moist, water-logged areas around freshwater swamps. Its population here is confined to a few pockets of freshwater swamps at the Central Catchment Nature Reserve.

More than 20 species of freshwater crabs and prawns have been recorded at the Central Nature Reserve. At least three of these freshwater crab species are found only in Singapore, including the Johora singaporensis (which was named after the country).

Malayan Pangolin

(Manis javanica)

Also known as the scaly anteater, its body is covered with a coat of "armour" or keratinised scales. It is one of the few mammals in the world which does not have any teeth. It feasts on only termites and ants, using its long and sticky tongue to lick them out from their nests.

The species is also found in the region but its population is threatened by rampant poaching and smuggling for the wildlife meat trade.

There are 53 mammals recorded in Singapore, more than half of which are found in the Central Nature Reserve. Mammals such as the Flying Squirrel and the Lesser Mousedeer help plants disperse seeds far and wide.

Two subspecies which are found only in Singapore are the Cream-coloured Giant Squirrel and the Banded Leaf Monkey.


Source: Dr Leong Tzi Ming, a zoologist, botanist Dr Shawn Lum and Mr Tony O’Dempsey, both from the Nature Society (Singapore).