These are the days of lasers in the jungle
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COMMENTARY
Open Access
These are the days of lasers in the jungle Joseph Mascaro1*, Gregory P Asner2, Stuart Davies3, Alex Dehgan4 and Sassan Saatchi5
Abstract For tropical forest carbon to be commoditized, a consistent, globally verifiable system for reporting and monitoring carbon stocks and emissions must be achieved. We call for a global airborne LiDAR campaign that will measure the 3-D structure of each hectare of forested (and formerly forested) land in the tropics. We believe such a database could be assembled for only 5% of funding already pledged to offset tropical forest carbon emissions. In a precious 152 minutes on the Lunar surface, Neil Armstrong and Buzz Aldrin raced to collect rocks, dust and photographs that are an enduring fascination in museums and laboratories—testament to the awesome effort expended to touch them. They left behind a discarded landing assembly, sprawling trails of footprints, and the flag of the United States. But they also left behind a science experiment about the size of a coffee table. This hunk of honeycombed metal may be the most important scientific legacy of the Apollo Program. It’s called a laser retroreflector, and it revolutionized our understanding of the Moon [1]. Laser ranging technology is straightforward: it works like radar or sonar but with lasers. Point a laser at a target and collect the reflected light bouncing back; with a stop watch fit for Einstein, you can measure the time delay between the laser shot and the return bounce to determine the distance to your target. Since the experiment began, we’ve learned that the Moon’s orbit is widening by 3.8 centimeters per year, slowing the rotation of the Earth by about 2.3 seconds per century. These changes give us the leap second, and in a few million years will make February 29th obsolete. The revelation has also dramatically influenced our thinking about the formation of the Earth-Moon system some 4.5 billion years ago. Just as the Moon’s history was disrobed by laser ranging 50 years ago, Earth’s tropical forests are giving up their secrets to the light. Airborne light detection and ranging— called LiDAR—has over the last ten years become a key tool that ecologists use to understand physical variation in * Correspondence: [email protected] 1 American Association for the Advancement of Science, 1300 New York Ave NW, Washington, DC 20001, USA Full list of author information is available at the end of the article
tropical forests across space and time [2,3]. Like an MRI of the human brain, LiDAR probes the intricate threedimensional architecture of the forest canopy, unveiling carbon that forests keep out of the atmosphere, and also the mounting threats to that carbon storehouse: drought, fire, clandestine logging and brash gold-mining operations [4]. Even the quintessential natural disturbance of the sunfilled light gap—long thought to enhance the incredibly high species diversity of tropical forests—has been deconstructed by laser technology [5]. Laser ranging in tropical forests is such a game-changing te
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