Laser to Map U.S. Forests
College Park, Maryland--ATo monitor the impact of deforestation on global climate, researchers must first determine the amount of carbon locked up in the world's trees. By pointing a laser at a forest and timing how long it takes reflected photons to return to the aircraft, researchers can determine the elevation of leaves, branches, and the ground--information useful for estimating total carbon.
Scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, developed the Laser Vegetation Imaging Sensor (LVIS) several years ago. The laser cuts a kilometer-wide swath, says Ralph Dubayah, a geographer at the University of Maryland, College Park. By training the instrument on Costa Rica in 1998, Dubayah's team was able to map the forest floor and estimate tropical biomass more accurately than with previous methods. This week the LVIS system is being used to map Maryland forests, and in the next few weeks scientists will turn its beam on forests in North Carolina, New Hampshire, and California.
This is the first aerial system that can take the measure of a forest from canopy to ground, says Russell Congalton, a forester at the University of New Hampshire, Durham. Researchers will have even more data to crunch next year if NASA's budget allows for the launch of a five-laser enhanced LVIS system into space. These lasers would create the first global maps of forest biomass and allow researchers to further refine global climate models.
--Kate O'Rourke