SINGAPORE - The tiring and unpaid labour of clearing swathes of 2m-tall elephant grass originating from Africa is how some people are spending their time along the northern part of the Rail Corridor.

Since Feb 10, volunteers for the Nature Society (Singapore), or NSS, have started planting native saplings in place of these invasive stalks, with the dream that the 1.3km stretch between the Kranji War Memorial and Sungei Kadut Avenue will become forest decades from now.

They join a global movement, known as rewilding or returning degraded landscapes to their natural state, in a bid to help ecosystems recover.

In Singapore, the authorities are expanding such projects by involving community groups in the long-term cultivation of the forest from seedlings to trees.

Along the Rail Corridor, volunteers from organisations including the United World College of South East Asia, as well as nearby residents of Hillview and Hindhede, regularly participate in removing invasive species and planting local flora.

National Parks Board (NParks) group director of conservation Lim Liang Jim said: “We want to build up a community of stakeholders, a community of stewards so that protecting our natural capital is literally in the hands of every individual in Singapore.”

Each native tree and shrub planted by volunteers is strategically selected for its ability to restore the natural rainforest, short-circuiting the process needed for a bare patch of land to evolve into secondary forest, said Mr Lim. With the climate changing, ensuring more diversity among plants also strengthens the forest to deal with periods of heavy rain or drought. This is why a variety of resilient species is planted, he added.

Since 2020, NParks has set up community nurseries in several places, including Dairy Farm Nature Park and Rifle Range Nature Park, where volunteers can learn and help in the processes of seed collection, plant propagation, cultivation and nursery management.

Along the Rail Corridor, volunteers in the NSS Rewilding Project have been roped in to propagate and plant up to 5,000 trees as well as track their growth, said project lead Ngo Kang Min.

The former Keretapi Tanah Melayu railway land holds special meaning for the group, which began its campaign for the 24km route to be turned into a green corridor in 2011, she added.

Dr Ngo, who has spent more than 15 years researching forest ecology, said: “Almost every habitat in Singapore can be found along the Rail Corridor – mangroves, grasslands, primary rainforest – because it goes past Bukit Timah Nature Reserve, secondary forest and swampland.

“The fact that all these different habitats are in this one stretch is the value we see in the Rail Corridor.”

By planting trees to create a continuous forest canopy, NSS hopes that the greened plot will attract wildlife like straw-headed bulbuls, which can be heard piping from the trees lining the Rail Corridor in Hillview, south of the rewilding site.

Over the past few years, Singapore’s forests have become a stronghold for the songbird species, which remains critically endangered globally even as the Republic houses up to a third of the world’s population.

Said Dr Shawn Lum, president of NSS: “It’s not just about planting trees, but establishing a functioning ecosystem that can allow species to move up and down the corridor.”

The saplings provide food and shelter for wildlife, which in turn helps to disperse their seeds, making the Rail Corridor not just a transport conduit for humans and cargo in the past, but of flora and fauna as well.

The Rail Corridor is one of the most important ecological connectors here linking the Southern Ridges, the Central Catchment Nature Reserve, the Western Catchment forest and forests flanking the north shore of Singapore, said ecologist David Tan.

Genetic similarities have been detected in some species living in the Southern Ridges and Central Catchment Nature Reserve, which suggest that the Rail Corridor has facilitated exchange between these forest areas that are far apart, he added.

Such movement is crucial for maintaining genetic diversity and preventing inbreeding among flora and fauna.

Likewise, animals like the forest-dwelling common palm civet are critical vehicles for native flora to flourish along the Rail Corridor.

Said wildlife ecologist Fung Tze Kwan: “Civets are important seed dispersers as they can feed on fruits in one area and move along the Rail Corridor and other park connectors and defecate seeds. This helps with regeneration.”

As habitat restoration paves the way for nature to rebound in the corridor, the authorities are also keeping an eye out for potential flashpoints between humans and wildlife, as they do in Singapore’s parks.

So far, there has been no sign of conflict along the pathway.

Said NParks’ Mr Lim: “A lot of the human traffic (in the Rail Corridor) is transient... so we don’t see monkeys hanging about because there’s nobody standing here to feed them. So hopefully it remains that way.”