When it comes to wetlands in tropical Singapore, the first thing that comes to mind is usually the mangroves lining along Singapore’s remaining natural coastlines. However, you may not have come across the freshwater swamp forests that used to cover 16% of Singapore’s land mass.

Figure 1. Map of primeval vegetation in Singapore

In an introduction video by NParks, the Deputy Director of the Singapore Botanic Gardens cited freshwater swamp forest to be “one of the rarest ecosystems that you can find in our city in nature”. However, by the turn of the 21st century, only 1.5% of the primeval freshwater swamp forest remained. Yet, these habitats host some of the unique biodiversity that gave its name as a biodiversity hotspot in the region.

Figure 2. Swamp forest crab, Parathelpusa reticulataI, found in Nee Soon Swamp Forest. It is regarded as critically endangered and is one of the three endemic crabs of Singapore (Credit: Zhi Wan)

 

Restoring a wetland

Given the dire state and small size of our last remaining freshwater swamp forest, the Nee Soon Swamp Forest, efforts have been made to make this unique ecosystem accessible to the general public at the Keppel Discovery Wetland in the Botanical Garden. The intention is to expose the visitors to the different ecosystems in Singapore and our local natural heritage.

Figure 3. Pulai Marsh, one of the key features of the Keppel Discovery Wetland (Credit: Shein)

On my trip to the Keppel Discovery Wetland with the GE4224 class, I was struck by the scenic view of Pulai Marsh (Figure 3).  The water bodies were created by flooding and damming the ponds to replicate the waterlogged condition. As a form of passive restoration, water from a natural spring was diverted to feed the marsh and ensure a continuous supply of water and nutrients. Part of the wetland conservation efforts, propagules were taken from both local and regional wetlands and planted to recreate the wetland vegetation of the freshwater swamp forest landscape. The Lipstick Palm found at the discovery wetland can be easily recognised by its vivid red stem and the palms and were in fact the descendants of the last remaining population in the Nee Soon Swamp Forest (Figure 4)!

Figure 4. Lipstick Palms, Cyrtostachys renda, in Keppel Discovery Wetland (Credit: Letitia)

Roadblocks and the way forward

Restoring a wetland swamp forest has its complications. While the waterlogged condition created at Keppel Discover Wetlands does replicate a key characteristic of the wetlands, abiotic factors such as sunlight, water acidity, and shade also affect and determine the living organisms in the water. These elements are harder to control and requires strategic planning and monitoring to assist native wetland habitants to thrive. With a quick glimpse of the pond, you will quickly notice the abundance of hydrilla. While these hardy aquatic plants are commonly seen in reservoirs, an abundance of these non-native aquatic plants are unwelcomed and damaging to sensitive wetland fish and plants. Moving forward, further research on the common characteristic of wetland ecosystem and unique species adaption can help to direct efforts to recreate a more conducive environment for wetland inhabitants and a hostile one to invasive species like the hydrilla. Let’s bring justice to the wild diversity of flora and fauna present in our least remaining swamp forest!

 

Figure 5. Nee Soon Swamp Forest (Credit: Fangling)

Written by: YU FANGLING