Trees play an important role in creating a livable environment, says NParks Conservation Group director Adrian Loo. “They serve as natural air filters, they reflect radiant heat and cool surfaces and [provide] ambient temperatures through shade and evapotranspiration; and help to mitigate the urban heat island effect and climate change,” he said. “Healthy forests also play a role in regulating the water cycle, slowing down floodwaters and cleaning the water that flows into waterways.”

The city also plans on more than doubling the amount of its “Nature Ways,” which aim to make the streets cooler and more aesthetically pleasing while replicating some of the habitat value of forests by planting trees, shrubs and ground cover along sidewalks.

“The planting along these Nature Ways [is] not only designed to cool the environment (with a higher leaf area index), but also attract butterflies, garden birds and small mammals, bringing biodiversity and nature into our urban landscape,” Loo said.

One of the many denizens of Singapore's forests is the mangrove pitta (Pitta megarhyncha). Image by JJ Harrison via Wikimedia Commons (CC BY-SA 4.0)
One of the many denizens of Singapore’s forests is the mangrove pitta (Pitta megarhyncha). Image by JJ Harrison via Wikimedia Commons (CC BY-SA 4.0)

Carbon storage champions

There’s another, not-so-local benefit to restoring mangroves: healing the global climate. Getting excess carbon out of the atmosphere through reforestation is a key strategy of multinational efforts to curb climate change. And research indicates that, pound for pound, mangroves can sequester far more carbon than rainforests do.

“Mangroves can store three to five times more carbon per hectare than other forest types can do,” Friess said.

Just why are mangroves so good at carbon storage? Friess said it’s because they are particularly effective at locking up carbon in soil.

“In a normal forest, leaves and branches would die, fall to the forest floor, and quickly get broken down by bacteria and fungi, which releases the carbon back into the atmosphere,” Friess said. “Mangrove soils are waterlogged so they have a different microbial community, so organic matter is not broken down and the carbon stays locked up in the soils.”

Mangrove roots hold in soil and prevent erosion while acting as a buffer to stormy seas. Image by Rhett Butler/Mongabay.
Mangrove roots provide sanctuary and nurseries for many marine animals, like this giant mudskipper (Periophthalmodon schlosseri). Image by Bernard Dupont via Wikimedia Commons (CC BY-SA 2.0).

Friess and his colleagues found that even at their current reduced extent, Singapore’s mangroves held 450,571 metric tons of carbon. However, this is not enough to compensate for the city-state’s emissions. A report by the National Environment Agency states that the city-state released 48.6 million tons of CO2 in 2014, the last year for which data are available.

Friess says the fact these mangroves are still found in modern metropolises such as Singapore gives him hope that they can hang on and make a comeback in other coastal cities as well.

“It gives you an idea of how resilient they are and that they can cope with these modified urban conditions,” he said.

Professor Lian Pin Koh, a conservation scientist and director of the new Centre for Nature-based Climate Solutions at the National University of Singapore, says natural measures like reforestation are hugely important because they are immediately deployable.

“Nature had already done the research and development, the proof of concept and even the implementations at scale of carbon capture and storage,” Koh said. “Manmade solutions are still many years and perhaps even decades away from becoming commercially viable and operational at scale.”

Scaly-breasted munia (Lonchura punctulata), one of the many bird species that inhabit Singapore's forests. Image by David Li.
Scaly-breasted munia (Lonchura punctulata), one of the many bird species that inhabit Singapore’s forests. Image by David Li.

When it comes to gauging the success of reforestation projects like One Million Trees, Jurgenne Primavera, former co-chair of the IUCN Mangrove Specialist Group, prefers to focus on science and ecology rather than targets or quotas. She said that problems with reforestation projects often arise when the wrong species are planted at the wrong sites. But she adds there are key signs when reforestation has been done effectively.

“High survival and growth rates and healthy forests of the correct trees species,” Primavera told Mongabay. “For mangroves, for example, these would be Avicennia marina and Sonneratia alba along coastlines facing the open sea. For terrestrial species these would be native species and not exotics.”

To safeguard the trees, NParks carries out regular inspections and offers best-practice workshops to organizations across the island. But Adrian Loo said that for the One Million Trees project to be considered effective, everyone needs to be involved: “The success of the project is also measured by our ability to instill a sense of stewardship among Singaporeans — towards our trees and environment.”


Banner image: Grey-headed fish eagle (Ichthyophaga ichthyaetus) by David Li.

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Article published by Morgan Erickson-Davis
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