Josef Kellndorfer and Wayne Walker of the Woods Hole Research Center recently worked with the U.S. Forest Service and U.S. Geological Survey to create this highly detailed map of all the trees in America. Over six years, researchers assembled the national forest map from space-based radar, satellite sensors, computer models, and a massive amount of ground-based data. The darkest greens reveal the areas with the densest, tallest and most robust forest growth.
Forests in the U.S. were mapped down to a scale of 30 meters, or roughly 10 computer display pixels for every hectare of land (4 pixels per acre). Kellndorfer estimates that their mapping database includes measurements of about five million trees. The map possibly provides the highest resolution and most detailed view of forest structure ever assembled for any country.
“Forests are a key element for human activity,” says Kellndorfer. “Resource managers need to see forests down to the disturbance resolution—the scale at which parking lots or developments or farms are carved out by deforestation. We have to know how much we have, and where, in order to conduct sound management and harvesting.”