I wish to add to senior transport correspondent Christopher Tan's lucid and rational commentary ("Cross Island Line debate misses elephant in room"; yesterday).
I have spent much of my time photographing and writing about the forests in Singapore and in the region.
While intact forests in the region offer unparalleled biodiversity, it does not mean the fragmented forests in Singapore have nothing to offer.
On the contrary, some things are easier seen in Singapore than anywhere else, for instance, flying lemurs and oriental pied hornbills.
The proposed Cross Island MRT Line (CRL) will cut through the core of our forests in MacRitchie.
The forests in MacRitchie are still revered by many as one of the last bastions of our natural heritage.
We have already lost many species of flora and fauna. Even soil investigation studies will have an irreversible effect on the forests.
Digging deep may affect the drainage and water supply to the forests, and the deleterious results may not be known until years later.
Escape routes along the proposed CRL tunnel will inevitably be built, which means more damage will be done to the forests in order to accommodate them.
There are lessons learnt from the construction of the non-elevated Bukit Timah Expressway (BKE), which separated the Bukit Timah Nature Reserve from the Central Catchment Nature Reserve.
An eco-link was built to try to mitigate the loss from the separation. But as an afterthought, it is a costly intervention.
I urge the authorities to abandon the idea and work on a line that skirts Thomson Road instead.
To recover what has been lost, nature needs a helping hand - it does not need further fragmentation; it needs time and protection to regenerate.
Chua Ee Kiam (Dr)