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Locals beat satellites to map carbon in Amazon

Locals beat satellites to map carbon in Amazon Jose MV Fragoso/Stanford University
04 Mar
Basic ecology fieldwork techniques may allow indigenous groups to beat satellite data on carbon storage in the Amazon

When researchers visit the Amazon the priority isn’t usually teaching fieldwork techniques. But a research team from Stanford University turned the forest into a classroom to better understand the Amazon’s carbon storage potential.

Based in Guyana, the team taught basic ecology techniques to measure carbon capture to indigenous people. Results from the research suggest that satellites used to monitor carbon capture may be underestimating the region’s potential by as much as 40 per cent.

‘The girth of trees was measured by indigenous people trained by project scientists,’ says project leader Jose Fragosos. ‘This measurement is needed to calculate the biomass of a tree.’

Two field workers per site sampled all trees with a girth greater or equal to 10cm. In total 604 plots were sampled across 20 villages and control sites.

‘The carbon density for these trees in plots was calculated using a standard calculation for this field of research,’ says Fragosos. ‘These real “ground-based” carbon densities and sites were then overlaid on a map we created using satellite imagery that identified the occurrence and distribution of eight classes of vegetation.’

By adding ground-based carbon data and locations to the map, along with the vegetation, the team could assess carbon stock levels over the broader region. Locals were taught to understand that all life is based on carbon using black charcoal from a burnt twig.

‘A handful of leaders had heard the term carbon and carbon stocks, but seemed generally unaware what this actually meant in physical terms,’ says Fragosos. Lessons in survey plotting, cataloguing plant species and measuring trunk circumferences followed.

‘In my estimation almost none of the field researchers we first trained were aware of carbon storage in the Amazon or elsewhere,’ says Fragosos. 

‘The serious nature of this lack of knowledge is exemplified by a statement from one of the most knowledgeable indigenous leaders from the Rupununi region, who stated that if Europeans were willing to pay for carbon stocks, maybe we could bottle our air and sell them that as well,’ he added.

Satellites may underestimate carbon storage because the satellites use broad vegetation classification, such as ‘forest’ or ‘grassland’, says Fragosos. Vegetation classes are more finely grained in some cases, he adds.

Satellites can also miss small-scale similarities and differences in forest and vegetation types, or different forest management strategies.

‘In our work we show there are potential underestimations in satellite-derived forest carbon values, but the more important point is that satellite-only estimations are probably not as accurate as on-the-ground measurements,’ says Fragosos. Measurements from the ground should be used to calibrate satellites measurements to improve accuracy, he adds.

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