Sunday, January 18, 2009

Central Catchment Nature Reserve

The Central Catchment Nature Reserve is the biggest nature reserve in Singapore, covering an area of 3043 hectares, though the area includes five reservoirs - MacRitchie, Upper Seletar, Lower Seletar, Upper Peirce and Lower Peirce reservoirs. The area was designated to be a nature reserve when the Nature Reserve Ordinance was enacted in 1951. However, the area was already protected since the early 1900s as a catchment area when the various reservoirs were constructed.

MacRitchie Reservoir

Most part of the nature reserve is covered by secondary forest, except for about 154 hectares of small primary dryland rainforest patches scattered around the reserve, and 87 hectares of primary freshwater swamp forest in Nee Soon.

According to The Natural Heritage of Singapore by Hugh T.W. Tan, L.M. Chou, Darren C.J. Yeo and Peter K.L. Ng, the Central Catchment Nature Reserve primary dryland forests are of the lowland dipterocarp forest type, of which the large dipterocarp trees, which are members of the meranti family (Dipterocarpaceae), are the most common tree species. Since the forest is characterised by a high proportion of the taller trees being in the red-meranti group of meranti species (Shorea spp.) and keruing (Dipterocarpus caudatus), it is further classified as the red meranti-keruing forest subtype. In Peninsular Malaysia, this type of forest occurs from sea level to about 300m attitude.

Dos & Don'ts
  1. Stay on the trail! Wandering off the trail may result in trampling of the flora and fauna.
  2. Bring water and some light snacks, but avoid eating or drinking when there are monkeys around.
  3. Do not feed any animals, as they may become very dependent on human to feed them, and forget how to find food on their own. Some animals, such as the macaques, may even learn to snatch food from human.
  4. Keep your volume down, or you may disturb the very animals you want to see, and they may hide away from you.
  5. Take nothing but photos, leave nothing but foot prints. Bring your litter out with you, and never take anything from the forest. Poaching has resulted in severe reduction in the population of much wildlife in many places.
  6. You may want to consider wearing long pants, e.g. light track pants etc. There could be mosquitoes.
  7. Please bring insect repellent. Mosquito pads are usually not very useful for such outdoor activities as the mosquitoes can be quite aggressive.
  8. Please bring a cap/hat in case of sunny weather, and raincoat/poncho in case of wet weather. I would also recommend bringing a few plastic bags to keep your electronic products in case it rains.
  9. Bring a camera along, but remember to have a plastic bag to keep it dry in case it rains.

Getting Started

The Central Catchment Nature Reserve includes several parks near the reservoirs with trails and boardwalk.

Boardwalk in Central Catchment Nature Reserve
Some of the boardwalks cut through the forested area, while others were built by the sides of the reservoirs.

HSBC TreeTop Walk
The main attraction of Central Catchment Nature Reserve is probably the TreeTop Walk. It can be accessed from Venus Drive, off Upper Thomson Road. A longer route will be from MacRitchie Reservoir Park via the MacRitchie Nature Trail.

And while you take your time strolling along the trail, do look out for any interesting wildlife by the sides.

The Forest Floor

Most parts of Central Catchment Nature Reserve are covered with secondary forests, though fortunately many of them are already very mature with continuous canopies. As such, there's usually very little undergrowth on the forest floor except at the edges, or perhaps, near the various trails when the canopy was broken. Mushrooms such as the one above can sometimes be seen, and they play the important role of breaking down dead plants, return them to the soil.

Pitcher plant (Nepenthes ampullaria)
Rainforest floors usually have little nutrients in the soil, and thus plants with the ability to obtain alternative sources of nutrients, such as this pitcher plant (Nepenthes ampullaria). Pitcher plants secrete a watery or syrupy fluid in their pitchers to drown insects attracted to them. The lower part of the pitcher contains glands to absorb nutrients from the captured prey.

Fern (Gleichenia truncata)
By the sides often trail, it is quite common to find various types of ferns growing, such as this Gleichenia truncata. Ferns are non-flowering plants, and they reproduce from spores.

Terrestrial flatworm (Bipalium sp)
Sometimes, if you are lucky, you may also spot terrestrial flatworms (Bipalium sp.) sliding over moist ground.

Giant forest ant (Camponotus gigas)
The giant forest ant (Camponotus gigas) is one of the biggest ant in the world! While they forage mainly at night, they are commonly spotted in the day too.

Jewel beetle
Many species of jewel beetles (Family Buprestidae) used to be found in our forest, but now, only the smaller species can still be regularly sighted. Their glossy iridescent colours, though beautiful, have unfortunately resulted in them being ended up in many insect collectors' collection.

Trilobite beetle (Duliticola hoiseni)
The trilobite beetle (Duliticola hoiseni) is an endangered beetle, but occasionally they can still be spotted on rotting wood, most often seen after rain. They are threatened by degradation of forest habitat, and in some places, also over-collection by collectors.

Singapore tarantula (Phlogiellus inermis)
The Singapore tarantula (Phlogiellus inermis) is not commonly seen by general users of the Central Catchment Nature Reserve, largely because it is usually found in leaf litter where its prey can be found, especially near the base of tree trunks in waste-land and gardens.

Harvestman (Order Opiliones) is a close relative of spiders. It's also known as daddy long legs. Like the spiders, it also has eight legs, but different from spiders, its two main body sections are nearly joined, and they also have no venom or silk glands.

Common sun skink (Mabuya multifasciata)
Forest skinks (Family Scincidae) can be a common sight if you look closely along the trails. The common sun skink (Mabuya multifasciata) can often be seen sunning itself along the path or running into the undergrowth when disturbed.

Clouded monitor lizard (Varanus bengalensis)
The clouded monitor lizard (Varanus bengalensis) can sometimes be seen foraging on the forest floor on smaller animals. They are mildly venomous, and are seen by scientists to be closely related to snakes.

Water stick insect (Ranatra sp.)
Since the Central Catchment Nature Reserve encompasses a few reservoirs, we can expect to find all kinds of aquatic life if you carefully into the shallow waters. This is a water stick insect (Ranatra sp.). It has strong front legs to catch prey like little fishes, tadpoles or other aquatic insects.

Forest snakehead (Channa lucius)
In some of the streams leading into the reservoirs, the forest snakehead (Channa lucius) can sometimes be seen. Snakeheads are characterised by their torpedo-shaped body, large scale-plated head and long dorsal and anal fins.

Copper-cheek frog (Hydrophylax raniceps)
And when you are near water bodies, amphibians can often be spotted or heard. The copper-cheek frog (Hydrophylax raniceps, formerly confused with Rana chalconota) exhibits different colours in the day and night. In the day, it is bright green on the back, but at night, it becomes greenish-yellow with brownish spots.

The Understorey

Leaf litter plant (Agrostistachys longifolia)
The understorey consist of a variety of taller shrubs and young trees. Little light reaches this area too. The leaf litter plant (Agrostistachys longifolia) has an interesting way to obtain more nutrients for itself. It has a roseate of leaves, allowing it to trap fallen leaves. When the leaf litter decomposes, the plant will extract the nutrients from it.

Thottea grandiflora
The Thottea grandiflora bears pretty flowers hanging down like purple lampshades.

Tongkat Ali (Eurycoma longifolia)
The Tongkat Ali (Eurycoma longifolia) can also be found here. This is a treelet that can grow up to about 15m tall. Historically, the roots of this tree has been used as a herb for its suggested aphrodisiac properties.

Tree ferns (Cyathea sp.)
Tree ferns (Cyathea sp.) in Singapore never really grow very tall, unlike the ones in Malaysia. They can be recognised from their large fronds on a distinct trunk.

Climbing fig (Ficus sp.)
Climbers, such as this climbing fig (Ficus sp.) are also a common sight in the Central Catchment Nature Reserve. These climbers do not extract nutrients from the host plant, but just climb on it for support to reach out for sunlight.

Green tree snails (Amphidromus atricallosus perakensis)
The plants were not the only organisms that climb though. Green tree snails (Amphidromus atricallosus perakensis) are sometimes spotted on the trees or buildings, but they are much harder to spot on the trees since they blend in nicely with their green coloration.

Red assassin bug (Cosmolestes sp.)
The assassin bug (Cosmolestes sp.) are regularly spotted stalking insects among the plant leaves. It has a dagger-like beak which it uses to stab its prey, injecting paralysing saliva into it, and breaking down its internal tissue into a partially digested liquid.

Tortoise beetle
The tortoise beetle (Subfamily Hispinae) is a type of leaf beetle which feeds on leaves or flowers.

Short-banded sailor (Phaedyma columnella singa)
Butterflies are a common sight in the Central Catchment Nature Reserve. The above is probably a short-banded sailor (Phaedyma columnella singa).

This a a dragonfly which I have not been able to identify so far. Dragonflies are commonly spotted by the water's edge.

Damselfly (Coeliccia octogesima)
So are the damselflies. This Coeliccia octogesima is a forest species, and is thus not usually seen in the more open areas. Unlike most of the other species of damselflies that I've seen, this one held its wings apart instead of holding them together vertically.

Long-spined spider (Macracantha arcuata)
With so many flying insects, we can also find many of their predators around. The long-spined spider (Macracantha arcuata) lives predominantly in primary rainforest, and thus is not commonly spotted along the trail.

Green-crested lizard (Bronchocela cristatella)
The green-crested lizard (Bronchocela cristatella) used to be the most common tree lizard in Singapore, but has largely replaced by the more aggressive changeable lizard, an introduced species.

Long-tailed Macaques (Macaca fascicularis) feeding on Dipterocarp fruit
Larger vertebrates like the long-tailed macaque (Macaca fascicularis) can also be seen at the Central Catchment Nature Reserve. Please do not feed these monkeys if you see them, as they have become more dependent on human for food, and are known to snatch food from people. They have sufficient food in the forest, so please leave them alone, so that they will eventually learn to leave you alone too.

Tree shrew (Tupaia glis)
Common tree shrews (Tupaia glis) can be spotted scampering among the shrubs and young trees. Sometimes mistaken to be squirrels, tree shrews are not rodents, but are placed in their own order, Scandentia. You can differentiate them from squirrels by their longer, pointy snouts.

Colugo (Cynocephalus variegatus)
A much harder to spot animal will be the colugo (Cynocephalus variegatus). It possess a thin membrane stretched to the ends of the tail and each limb, this animal is able to glide from tree to tree!

The Canopy

Tiup tiup (Adinandra dumosa)
Since most part of the Central Catchment Nature Reserve is covered with secondary rainforest, the canopy is often the topmost layer seen by visitors. The tiup tiup (Adinandra dumosa) is a common secondary forest tree that can be found at the edge of the reserve. The flowers are cream-coloured with a long style each, and never open fully.

Mempat (Cratoxylum maingayi)
Several tall mempat (Cratoxylum maingayi) can also be found in the reserve. This native one is closely related to the ones we can usually find planted on our roadsides. It too, is deciduous, and after it shed its leaves, the entire crown will be covered with reddish young leaves and pink flowers.

Singapore Durian (Durio singaporensis)
The Singapore Durian (Durio singaporensis) can be found along Petaling Trail. The seeds do not have much flesh surrounding them like the commercial durian species.

benjamin's fig (Ficus benjamina)
Sun-loving species of fig trees, such as this benjamin's fig (Ficus benjamina), can be commonly found at the edge of the reserve. However, many of the primary forest species are much less common these days, since their dispersal agents like the bigger hornbill and forest pigeon species are now extinct in Singapore. Fig trees, however, remain an important source of food and shelter for many animals in the forest, since they flower regularly and have lots of hiding places for small animals among their aerial roots.

Giant rattan (Plectocomia sp.)
At the canopy, we do not only see the crown of trees, but sometimes, we can find climbers too. The giant rattan (Plectocomia sp.) is one of them. Rattans are climbing palms belonging to the Palmae family, and many of them can be use to make into furniture and handicrafts.

The Emergent Layer

While most part of the Central Catchment Nature Comprises secondary rainforest, there are still a number of small patches of primary forests, and it is in these small patches where one can find the forest giants.

These giant towering trees, the dipterocarps, are taller than the canopy. These trees often flower in synchrony, usually once every 3 to 8 years. The flowering is often triggered by a prolonged dry spell.

Shorea flowers
These are the flowers of a Shorea sp.

These are the fruits of the same Shorea sp. Dipterocarp fruits often have wing-like structures to allow them to be dispersed by wind.

These fruits belong to Anisoptera megistocarpa.

The Dipterocarpus kunstleri can also also be found here, and these are the fruits. They are rather large, and each wing is at least 10cm long.

These were the biggest dipterocarp fruits, probably a Dipterocarpus grandiflorus, I have seen so far in the Central Catchment Nature Reserve. Each was more than 20cm long!

The Transitional Forests

Many parts of the Central Catchment Nature Reserve are seen are transitional forests - meaning, they are recovering from the previous logging and have become mature forests, on the way to become a more species rich forest.

They show that if given time, a degraded forest can recover. However, it can never return to its former glory, at least, not even in a few thousand years' time. That's because many of the seed dispersal agents are already extinct in Singapore, and these plant species which relied on these agents are fast disappearing from our forest.

True enough, we can manually replant these trees, but a forest is never complete without its fauna. Till the day when the big predators like leopards and tigers, and huge herbivores like elephants and deers, and big birds which disperse seeds like hornbills (which one species has returned to our northern forests) and big pigeons, our forest, sadly, will never be complete.


Hugh Griffith said...

Thanks for a spectacular, informative tour.

Ron Yeo said...

Thanks for the compliment, Hugh :)

Anonymous said...

nice blog:)

Ron Yeo said...

Thanks :)

Anonymous said...

Great tour, super commentary & photographs

Ron Yeo said...

Thanks for visiting my blog! :)

Anonymous said...

Wow, this is amazing!

I hope you don't mind that I use one of your pictures for my blog (I linked your blog).

Here is my blog

Koenigia said...

I'm visiting Singapore in September and as a biologist this has to be on my 'must see' list! Thanks for the informative tour!

Ron Yeo said...

Don't mention it. Thanks for visiting my blog, and hope that you will enjoy your stay in Singapore! :)