Estimating the absorptive capacity of a tree requires three measurements: height, circumference, and wood density, which varies by species.
As an assistant looks through binoculars at birds that might hit the drone, the machine flies a path plotted in a computer program.
“We collect data or capture (images) every three seconds,” explained FORRU field research officer and drone operator Vorayut Takeev.
“The overlapping images are then rendered into a 3D model that can be viewed from different angles.”
The section of woodland being surveyed is part of a decades-long project led by Elliott and his team to reforest an area of about 100 hectares by planting a handful of key species.
Their goal was not large-scale reforestation, but rather to develop best practices: planting native species, encouraging the return of animals that brought seeds from other species, and working with local communities.
The 3D model of the drone is a powerful visual representation of their success, especially compared to nearby untouched control plots.
But it is also being developed as a way to avoid labor-intensive ground surveys.
“Once you have the model, you can measure the height of each tree in the model. Not samples, but each tree,” Elliott said.
A forest’s carbon capacity goes beyond its trees, however, as leaf litter and soil also serve as stores.
So these have also been collected for analysis, which Elliott says shows that his reforested plots store carbon at levels close to nearby unaffected woodland.