NASA Creates World's First Global Forest Map Using Lasers

NASA Satellite Maps Trees Photo
Image by Jesse Allen and Robert Simmon

Scientists, using three NASA satellites, have created a first-of-its-kind map that details the height of the world's forests.

The data was collected from NASA's ICESat, Terra and Aqua satellites. The latter two satellites are responsible for most of NASA's Gulf spill imagery. The data collected will help scientists understand how the world's forests both store and process carbon. While there are many local and regional canopy maps, this is the very first global map using a uniform method for measure.

NASA Satellite Photo
Image by NASA/Scientific Visualization Studio/Chris Meaney

The laser technology called LIDAR was used to capture the data. It is capable of taking vertical slices of surface features. It measured the forest canopy by shooting a pulse of light at the surface and observed the time it took to return in comparison to the time recorded for the tree top.

Image by Jesse Allen and Robert Simmon

"LIDAR is unparalleled for this type of measurement," said Michael Lefsky of the Colorado State University, responsible for capturing the data. He explains that it would have taken weeks to capture this data in the field where LIDAR can capture it in seconds.

The map is based on data from more than 250 million laser pulses collected over 7 years.

The new map confirms that the world's tallest forests are clustered in the Pacific Northwest of North America and some parts of Southeast Asia. Temperate conifer forests--which are moist and harbor species such as Douglas fir, western hemlock, redwoods, and sequoias--have the tallest canopies (over 131 feet high). Undisturbed tropical rain forests are about 82 feet high, around the same height as oak and birch trees.

NASA Satellite Maps Trees Photo
Image by Jesse Allen and Robert Simmon

"What we really want is a map of above-ground biomass, and the height map helps get us there," said Richard Houghton, an expert in terrestrial ecosystem science.

But what about the carbon? Humans release over 7 billion tons of carbon every year. The atmosphere gets most of it (3 billion tons) while the ocean gets around 2 billion itself. But scientists have long wondered where the remaining 2 billion tons of carbon goes. They suspect forests capture most of it through photosynthesis, with younger forests absorbing more than older ones.

Surely, we can speculate what this kind of map can tell us about climate change. But as Lefsky points out, "This is a really just a first draft."

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Source: NASA