24 June 2010

How much mangroves are left in Singapore now?

We now know the answer, thanks to a wonderful paper by Yee, A. T. K., W. F. Ang, S. Teo, S. C. Liew and H. T. W. Tan!
Here's what I learnt from this valuable paper.

How much mangroves do we have left?
The study found that the total area of mangrove forest in Singapore is estimated to be 6.59 km2 (659 ha), which is about 0.95% of Singapore’s total land area. This does not include remnants of mangrove patches that are not influenced by the tides (either land-locked or within a reservoir).

Where are most of our mangroves?
The mangrove forest patches are mostly clustered at the north of Singapore, the authors say "presumably owed to the lower wave energy in the Straits of Johor, making the establishment of mangrove propagules easier, and allowing better growth of the trees."

Where is the largest mangrove in Singapore?
The largest fragment of mangrove forest is found at Sungei Buloh Wetland Reserve, with size of 1.17 km2 (116.8 ha).

How does this compare with the past?
The area of mangrove forests in 1819 was estimated to be 75 km2 (7,500 ha) Most of the mangrove forest area (approximately 70 km2), was found on the mainland.
During the British colonisation, about 11.60 km2 of mangrove forest was lost to charcoal and firewood exploitation, and land reclamation. After Singapore separated from Malaysia in 1965, rapid urban development and land-use changes occurred to meet the urgent and growing needs of a developing nation. During this period of national growth, mangrove forests suffered considerable losses owing to conversion to prawn ponds, further land reclamation projects, and damming rivers for the creation of the coastal reservoirs.

It was hard work to retain even the tiny proportion of remaining mangroves!

The authors say:
"Due credit must be given to various governmental, non-governmental organisations for mangrove protection and reforestation. The successful protection and preservation of mangrove forests in any country can only come about through the political will and commitment by the government with the participation of its citizens. This is usually demonstrated through public awareness and education of the natural environment by the citizens, followed by the gazetting of these areas by the government as reserves, thus rendering legal protection.

The first mangrove forest reserves in Singapore were established in 1885, though by then most of these areas were already badly degraded. However, this protection did not persist long as most of these reserves were abolished in 1938, being exploited for shrimp farming, and making way for various urban developments (Tan et al., 2010). The last stronghold of legally protected mangrove forest in Kranji was lost for reservoir damming in 1973. So by 1992, mangrove forests in Singapore were estimated only to cover 4.83 km2. The imminent threat to this habitat and its ecosystem services was later realised by the Singapore government because efforts to preserve the remnant mangrove forests were shown through the official gazetting of the mangrove forest area at Sungei Buloh in 2002 and also the incorporation of mangrove forest strips in urban parks (e.g., Admiralty Park, Pasir Ris Park,
Sengkang Park and Woodlands Town Park)."

Indeed, it is thus heartening to hear the recent plans for a bigger and better Sungei Buloh. As well as the serious effort to protect the mangroves at Pulau Tekong!

Read the paper on Nature in Singapore on the Raffles Museum of Biodiversity Research website: Yee, A. T. K., W. F. Ang, S. Teo, S. C. Liew & H. T. W. Tan, 2010. The present extent of mangrove forests in Singapore. Nature in Singapore, 3: 139–145. [PDF, 594 KB]

Thanks to Siva for the alert on the paper.

Here's some photos of my favourite mangroves in Singapore, those growing in the unlikeliest of places!

Mangroves are growing on the artificial seawall on Pulau Hantu! There are also a few mangrove trees in the Pulau Hantu lagoon.
Mangroves on the seawall on Pulau Hantu

Three rare Api-api jambu (Avicennia marina) have settled on the Semakau Landfill!
Api-api jambu (Avicennia marina)

Mangroves have been allowed to grow back along Sungei Api Api, next to HDB flats. Awesome!
Mangroves at Sungei Api Api next to HDB flats

I saw this rare Mentigi (Pemphis acidula) with some mangroves, growing wild on a remote reclaimed shore at Changi East.
Pemphis acidula

More photos of our mangroves and mangrove plants on wildsingapore flickr.

Read more about our mangroves on the wild fact sheets.


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