Beneath the mangrove roots: measuring carbon without cutting down trees

You might picture him behind a remote sensing screen. Kevin Koriantsoa prefers an auger. As a carbon engineer at Bôndy, he measures the stock of the Ma Honko mangroves by taking core samples, without felling a single tree. Three questions.

Kevin Ravelosamiariniriana Koriantsoa spends part of his year on Ma Honko, in the mud and salt of the mangroves. What he brings back: measurements, figures, and carbon read directly from the wood of the trees.

What exactly are you measuring at Ma Honko?

Two things. The carbon stock present in the mangrove ecosystems, including the soil, through sample collection and forest inventories. And tree growth, via dendrochronology: we read radial growth from wood cores. The second measurement sheds light on the first, because it indicates future sequestration potential, not just the current stock.

How do you take samples without damaging the site?

Our interventions are non-destructive. No trees are cut down; we use core sampling to take small specimens. Soil is collected from small areas and then backfilled after sampling. The principle is to leave the site exactly as it was before the team arrived.

Why fieldwork instead of remote sensing?

Both approaches exist and they complement each other. However, this is the first study of the Ma Honko site. Without real, local data, a model remains just a hypothesis. Fieldwork reduces uncertainty and provides the baseline upon which estimation models can be calibrated, then expanded via remote sensing and GIS on a larger scale.

The protocols followed are those of the CIFOR (Kauffman and Donato, 2012) and published research on Malagasy mangroves, from Jones et al. in 2014 and 2016 to Ratefinjanahary et al. in 2025.