From the air, the Amazon forest may just seem like a big swath of green, one tree much like the next. But look closely, and it’s a lot more complicated than that. Depending on the species and its precise location, trees will have different chemical compositions, grow at different speeds, and take on greater and lesser roles in sequestering the carbon that causes climate change.
You get a sense of this arboreal variety in the maps here. Taken in Peru, they’re the latest images from the Carnegie Airborne Observatory, a special twin-engine plane that flies above the most environmentally-important forests in the world. The CAO–which we first covered here–uses pulsing lasers to map forests in 3-D, and an onboard spectrometer that measures for chemical characteristics.
“These maps are colored to show the different chemicals in the forest canopy. By looking at their chemical signatures, we determined that different colors represent different species or communities of species,” says Greg Asner, who leads the research at the Carnegie Institution for Science.
In the image showing the Amazon river system, the trees in red contain more “growth chemicals” than the ones in green and yellow. That means they’re probably sequestering carbon at a faster rate than their neighbors, and therefore can be expected to become larger, relatively speaking, over time. The differences are explained by variations in elevation and underlying soil content. “This new work shows us that forests change in terms of their composition. The chemicals we detect in the canopies give us a rate of carbon dioxide uptake by the trees,” Asner says.
The CAO maps should help make conservation more cost-effective, showing which trees are most important from an environmental point of view. “By knowing where forests change in composition, conservation can focus on saving a portfolio of different forest types instead of making the mistake of saving just one or a few,” Asner says.