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What is ground-truthing?

STRI associate scientist Catherin Potvin unfurls a multicolored map and Javier Mateo, one of her Ph.D. students from McGill University, checks the expedition’s GPS coordinates. "The plane passed over about 300 meters that way," he says, pointing deeper into the forest in the remote eastern part of the province of Panama. Potvin’s team of local and international experts gathers its gear and crosses into the swath of forest directly measured with airborne Light Detection and Ranging.

Forest GEO Carbon Map

Armed with machetes, compasses and tapes to measure the circumference of trees, Potvin’s team hacks into the bush and marks off one-hectare patches of forest. They then break into smaller groups and record the girth, height and species of the largest trees in the plot. The data is later crunched into the mathematic equations used to estimate the carbon stock of each hectare.

On a good day, the team measures two or three plots. Oppressive heat, fallen trees, thick shrubs, wasp nests and weak GPS signals slow their progress. Yet this is an essential step to verifying the carbon stocks on the map produced by STRI and the Carnegie Airborne Observatory. Known as ground-truthing, the results Potvin and local communities produce will help improve the accuracy of the carbon estimates.


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