Checking latest measurements and satellite data prior to Congo peatlands expedition. Credit: Kevin McElvaney/Greenpeace
Davenport, I.J., McNicol, I., Mitchard, E.T.A., Dargie, G.C., Ifo, S.A., Milongo, B., Bocko, Y.E., Hawthorne, D., Lawson, I.T., Baird, A.J., Page, S.E., Lewis, S.L. 2020. First Evidence of Peat Domes in the Congo Basin using LiDAR from a Fixed-Wing Drone. Remote Sensing. 2020, 12, 2196.
First Evidence of Peat Domes in the Congo Basin Using LiDAR from a Fixed-Wing Drone
Plain language summary
In February 2019, we flew a drone across a vast area of peat swamp forest in the central Congo Basin to map the surface of the peatland for the first time. We found evidence of a dome shape, with the peatland being at a higher elevation in the middle than at the edges. This shape is typical of peatlands that are caused by high rainfall collecting on the ground surface, resulting in slow decomposition of dead plants and the formation of peat. This new information helps tell us how the peatland may be affected by future environmental and land use change.
Our ground surveys had previously identified the central Congo peatlands as being the world’s most extensive tropical peatland, storing 30.6 billion tonnes of carbon. We believed that this peat swamp forest is wet because it is rain-fed, rather than being wet because of inputs of water from rivers, but satellite-based remote sensing did not show the dome shape typical of other rain-fed tropical peatlands. By using a fixed-wing drone flown inwards from the edges of the peatland, we were able to measure ground elevation extremely accurately, to within a centimetre, using a laser altimeter, and identify a dome about 2-3 metres high.
The height of the dome is shallower than other rain-fed peatland domes, which reach as high as 20m in South-East Asia. This difference is probably because the rainfall in the central Congo Basin is around half that of many Asian and other tropical peatlands. Expeditions on foot deep into the interior of the peatland, combined with the drone data, show that this area of peatland formed in a shallow basin 3-4 metres deep and 40 kilometres wide. The peat began forming about 11,000 years ago, as this part of the world got warmer and wetter, according to radiocarbon dating of the peat samples.
Dargie, G.C., Lawson, I.T., Rayden, T.J., Miles, L., Mitchard, E.T.A., Page, S.E., Bocko, Y.E., Ifo, S.A., Lewis, S.L. 2018. Congo Basin peatlands: threats and conservation priorities. Mitigation and Adaptation Strategies for Global Change. 24(4), pp.669–686.