Scientists have produced a first-of-its kind map of the height of the world's forests by combining data from three NASA satellites. The map will 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. Maps of local and regional forest canopy have been produced before, but the new map is the first that spans the entire globe using one uniform method. The map was based on data collected by NASA's Terra and Aqua satellites, along with the Ice, Cloud and land Elevation Satellite, or ICESat.
Michael Lefsky, a remote-sensing specialist from Colorado State University in Ft. Collins, produced the final product. Lefsky describes his results in a journal paper to be published next month in Geophysical Research Letters. The new map shows the world's tallest forests are clustered in North America's Pacific Northwest and portions of Southeast Asia. Shorter forests are found in broad swaths across northern Canada and Eurasia. The primary data Lefsky used was from a laser technology called lidar on the ICESat.
Lidar can capture vertical slices of forest canopy height by shooting pulses of light at the ground and observing how much longer it takes for light to bounce back from the surface than from the top of the forest canopy. Since lidar can penetrate the top layer of forest canopy, it provides a detailed snapshot of the vertical structure of a forest. "Lidar is unparalleled for this type of measurement," Lefsky said. "It would have taken weeks or more to collect the same amount of data in the field by counting and measuring tree trunks that lidar can capture in seconds."
Michael Lefsky, a remote-sensing specialist from Colorado State University in Ft. Collins, produced the final product. Lefsky describes his results in a journal paper to be published next month in Geophysical Research Letters. The new map shows the world's tallest forests are clustered in North America's Pacific Northwest and portions of Southeast Asia. Shorter forests are found in broad swaths across northern Canada and Eurasia. The primary data Lefsky used was from a laser technology called lidar on the ICESat.
Lidar can capture vertical slices of forest canopy height by shooting pulses of light at the ground and observing how much longer it takes for light to bounce back from the surface than from the top of the forest canopy. Since lidar can penetrate the top layer of forest canopy, it provides a detailed snapshot of the vertical structure of a forest. "Lidar is unparalleled for this type of measurement," Lefsky said. "It would have taken weeks or more to collect the same amount of data in the field by counting and measuring tree trunks that lidar can capture in seconds."
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