Deforestation and removal of mangrove areas for conversion to aquaculture, agriculture, urban and coastal development have led to mangrove forests being once considered one of the most threatened habitats on the planet. Lesser known is how mangroves are actually one of the most productive and biologically diverse ecosystems in the world, with millions of people in coastal communities relying on them for fisheries, fuel wood, medicines and coastal protection.

However, recent international efforts have turned this habitat into an emerging conservation success story. Joining in these efforts is Associate Professor Dan Friess and his research team from the Department of Geography at NUS Faculty of Arts and Social Sciences. A coastal geographer, he is passionate about conserving mangroves and their ecosystems so that they may continue protecting delicate sea life, coastlines and help in the fight against climate change. Assoc Prof Friess is also concurrently Deputy Director of the NUS Centre for Nature-based Climate Solutions that brings together an interdisciplinary group of researchers for policy-relevant research and education on nature-based solutions for climate mitigation and adaptation in the Asia-Pacific. In addition, he is Deputy Director of the NUS Bachelor of Environmental Studies programme and a member of the International Union for Conservation of Nature Mangrove Specialist Group.

We sat down with him on 26 July – the United Nations’ International Day for the Conservation of the Mangrove Ecosystem – to talk about his love for mangroves, why they matter and how the community can play an important role in their conservation.

Why are you interested in mangroves?

Assoc Prof Friess: Mangrove forests are much more than just a topic of academic interest. My first field projects quickly showed me how crucial this ecosystem is to coastal communities – the food we ate came from the mangrove, the places we slept in were built using mangroves, the villages we stayed in were protected from storms by mangroves. The livelihoods of many coastal communities are strongly linked to resources that can be extracted from the forest. So, I am interested in mangroves because there is always an opportunity for our research to be translated into on-the-ground and policy actions that will improve people's lives.

Why are mangroves so important to climate mitigation and adaptation, and coastal protection, for Singapore?

Assoc Prof Friess: Mangroves are an important nature-based solution in our fight to mitigate climate change. They sequester high carbon dioxide out of the atmosphere at high rates, and they are able to store this carbon at high densities because the carbon does not get broken down once it accumulates in their waterlogged soils. Even though mangroves do not cover a huge area globally, they are able to store carbon more efficiently than other forests, so mangroves are able to make a small, but meaningful contribution to our climate change mitigation efforts.

In tandem with mitigating climate change, we also have to adapt to its effects. Mangroves help us do this by trapping sediment floating in the water, which deposits on the mangrove surface. By this mechanism, the surface of some mangroves may be able to rise at the same rate as sea-level rise. This is not something that seawalls can do, so mangroves might be a more flexible and "future-proof" form of coastal defence. Also, mangroves are great at coastal defence, because their tangled aboveground roots act as a sponge to incoming waves. Our recent modelling study showed that Singapore's mangroves can reduce wave heights by as much as 75 per cent during a storm.

You had mentioned that mangroves are difficult to restore once they are lost, why is that so?

Assoc Prof Friess: Mangroves are harder to restore than many other types of forests, because the sea is a very tough place to live. Only a few tree species around the world have evolved to tolerate some level of tidal flooding, waves and high salinity. So, mangrove restoration means more than just planting, it means fixing the local environment so that mangroves are in the right conditions to grow.

Mangrove deforestation can substantially change the physical environment, so restoration often requires a degree of engineering. Hence, it is much more cost-effective to protect mangroves that we have, rather than try to replace the ones we have lost.