MacRitchie’s irreplaceable habitats and biodiversity

A place like no other in Singapore; read on to find out about why it is so special.

Pristine forest habitats

The area in concern is a legacy left behind by the declaration of a Municipal Catchment for MacRitchie Reservoir in 18671. This mature regrowth forest is almost 150 years old now, forming an important seed bank for the regeneration of surrounding forests.

Situated in the core area of the Central Catchment Nature Reserve (CCNR), it also sports patches that make up a significant proportion of Singapore’s remaining primary lowland dipterocarp forest. Only 0.49% (2 km2) of this vegetation type is left in Singapore1. What is remaining cannot afford anymore impact.

The proposed Cross Island Line (CRL) also passes near natural stream systems. These streams have vastly different biophysical characteristics such as lower temperature, pH and velocity, as compared to the concretized waterways we are more acquainted with. Many native freshwater organisms can only thrive in these natural streams, beyond which hardier alien species that have been introduced by Man have largely taken over.

MacRitchie biodiversity


Throughout Singapore’s history of development, especially since the 19th century, we have lost about a third of our native forest fauna along with extensive deforestation2. Primary and mature regrowth forests in CCNR today still house more than half of the country’s residual native biodiversity2, representing their last population strongholds. Further extinction would mean loss of seed dispersal agents, stunted forest regeneration, ecosystem degradation, etc.

Learn more about MacRitchie’s threatened flora and fauna here.

Impacts of tunneling

CRL impacts

Works associated with the construction of CRL threaten to damage the irreplaceable habitats and biodiversity of MacRitchie Forest. Tunneling, although seemingly of little impact to surface ecosystems, can in fact cause problems related to alteration of underground hydrology, disturbance to fauna by ground-borne noise, and loss of pressure to surface, requiring extensive works above the affected site.

Site investigation. Of greatest and most immediate concern are site investigation works to determine if the substrate is suitable for tunneling. The operation of boring machines and the geophysical surveys can potentially be damaging. Noise, soil compaction, alteration of forest microclimate, loss of topsoil to erosion, siltation and toxic contamination of stream systems are all possible consequences should site investigation works proceed. Read the Environmental Impact Assessment (EIA) report for more details.

Next: Forest fragmentation

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1 Nature Society (Singapore), 2013. Cross Island Line Discussion and Position Paper. Retrieved from
2 Brook, B. W., Sodhi, N. S., & Ng, P. K. L., 2003. Catastrophic extinctions follow deforestation in Singapore. Nature424(6947): 420–426.

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