Posted on behalf of Adam Mann

Researchers have mapped a new dimension of the world’s forests: their height. The map, described in a paper in press at Geophysical Research Letters, will help estimate the total biomass in the Earth’s forests, an important component of understanding the global carbon cycle.

Over the course of 7 years, Michael Lefsky of Colorado State University used three NASA satellites – ICESat, Terra, and Aqua – to create a one of a kind map of the planet. He employed a technique called LIDAR, which estimates tree height by observing how much longer it takes a laser beam to return from a tree’s base than from its top.

Even after analyzing more than 250 million laser pulses, Lefsky had only plotted 2.4% of the Earth’s forests. But from this small sliver, he was able to generalize the results for the whole globe, combining the LIDAR data with another dataset acquired by the Terra and Aqua satellites.

The final image highlights the world’s tallest trees; 40-meter Douglas fir, redwoods, and sequoias found in the Pacific Northwest that far surpass the shorter, 20-meter spruce, fir, pine, and larch of boreal forests in the Earth’s northern latitudes. Between these extremes are 25-meter tropical rain forest trees and the oak, beeches, and birches common in deciduous forests in Europe and much of the United States.

Image: Michael Lefsky