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Peat Soils vs. the Forests Above: Which Holds More Carbon?

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At first glance, tropical peat soils might not seem all that exciting. Dead branches and leaves that have not fully decomposed because of waterlogged conditions? Once upon a time, even I might have found this, well, boring.

Peat soils can be difficult to relate to. Unlike the tropical forests they support, we cannot walk in their midst and stare at the surrounding majesty. Instead, the closest we can get is to walk upon them, with the swampy ground pulling at our boots. “Save the Mud!” doesn’t have quite the same ring as, “Save the Forests!” But once you know the facts, things can get pretty exciting because tropical peat stores crazy amounts of carbon.

This peat swamp forest in Sumatra, Indonesia may seem exciting, but underneath these walkways is where the real action happens.  Flickr user: CIFOR

This peat swamp forest in Sumatra, Indonesia may not seem exciting, but underneath these walkways is where the real action happens. Photo: CIFOR

The carbon story

The amount of carbon held in tropical peat is estimated around 88.6 billion tonnes worldwide—if all this carbon were released into the atmosphere as carbon dioxide, it would be the same as burning all proven oil reserves from Saudi Arabia, Venezuela, Canada, Russia, and the United States. That’s a scary amount of heat-trapping emissions.

Yet these huge numbers are difficult to comprehend. I only truly began to understand the necessity of protecting these ecosystems when I compared it to the carbon stored in the forests above the peat. On average, even peat that is only 1 meter (~3.3 feet) deep stores more carbon than its aboveground vegetation. This is especially problematic because there are some actors, such as the Indonesian government, that differentiate between peat of less than 3 meters (~9.8 feet) and peat which is more than 3 meters. Aside from protected areas, Indonesia only safeguards the latter. But as can be clearly seen from the figure below, even peat of just three meters can contain around ten times as much carbon as the forest above it.

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Aboveground peat swamp forest biomass is estimated to sequester 100-150 tonnes of carbon per hectare. And while carbon concentrations of peat vary based on vegetation, depth, water table, and location, a conservative estimate is about 500 tonnes of carbon for every meter depth per hectare. This means that even one meter of peat contains more than three times the amount of carbon as the forest above.

Oh, and one other terribly important point. Most lowland peatlands in Southeast Asia are dome-shaped. This means that while some peat in the dome (near the edges) may be on the shallow side, other peat (closer to the center) may be much deeper. Yet draining or destroying the shallower peat around the edges of the dome would likely have cascading effects elsewhere, putting deeper peat at risk as well.

Save the Mud!

To me, understanding the significance of peat means one important thing: we must do everything we can to protect remaining tropical peat soils, regardless of their depth.  Whether this means pushing Indonesia to expand peat protections, asking businesses commit to using palm oil that is free of any form of peatland destruction, or changing certification standards, there is too much carbon at risk to do anything less.

Posted in: Global Warming, Tropical Forests Tags: , ,

About the author: Lael Goodman is an analyst with the Tropical Forest and Climate Initiative at UCS. She conducts research and analysis to support reducing tropical deforestation as a way to mitigate climate change. Specifically, Ms. Goodman focuses on deforestation caused by the palm oil industry and protecting tropical peatlands. See Lael's full bio.

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  • Yosef Riadi

    Nice. Simple and easy to understand. If I may suggest perhaps you could also compared carbon sequistered in mangrove forest and aboveground forest too as the they store carbon differently. Yes it is tricky as some mangroves grow deep in peat forest too. Anyway nice reading your piece.

    • Lael Goodman

      Thanks, Yosef. I agree that it is important to know the carbon-sequestering capabilities of many different types of wetlands, as these systems have been undervalued for far too long. Thanks for the suggestion and for reading!

  • richard

    Thanks for clarifying something which I suspect very few of us really know much about. More reasons for UCS members to support efforts being made to save peat!

    • Lael Goodman

      Thanks Richard- for the feedback and for reading!

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