Using satellite data, scientists have produced a first-of-its kind map that details the height of the world's forests. Although there are other local- and regional-scale forest canopy maps, the new map is the first that spans the entire globe based on one uniform method.
The map, based on data collected by NASA's ICESat, Terra, and Aqua satellites, should help scientists build an inventory of how much carbon the world's forests store and how fast that carbon cycles through ecosystems and back into the atmosphere.
This new global depiction shows the world's tallest forests clustered in the Pacific Northwest of North America and portions of Southeast Asia, while shorter forests are found in broad swaths across northern Canada and Eurasia. Temperate conifer forests which are extremely moist and contain massive trees such as Douglas fir, western hemlock, redwoods, and sequoias have the tallest canopies, soaring easily above 40 meters (131 feet). In contrast, boreal forests dominated by spruce, fir, pine, and larch had canopies typically less than 20 meters (65 feet). Relatively undisturbed areas in tropical rain forests were about 25 meters (82 feet), roughly the same height as the oak, beeches, and birches of temperate broadleaf forests common in Europe and much of the United States.
"This is a really just a first draft, and it will certainly be refined in the future," said Michael Lefsky, the remote sensing specialist from Colorado State University who made the map. Lefsky described his results in a scientific report that has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
The forest-height map has implications for an ongoing effort to estimate the amount of carbon tied up in Earth's forests and for explaining what sops up 2 billion tons of "missing" carbon each year. Humans release about 7 billion tons of carbon annually, mostly in the form of carbon dioxide. Of th
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NASA/Goddard Space Flight Center