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Now Playing: Hawaii Forests—in 3-D!

New technology helps protect the Islands’ natural resources.


At this very moment, scientists around the globe are trudging through forests, shooing away mosquitoes and sweating bullets in a laborious effort to study Earth’s ecosystems. So imagine their excitement over a new high-tech device that can create 3-D images of every plant and tree within 40,000 acres—all in one day. Dubbed the Carnegie Airborne Observatory (CAO), the machine can provide each species’ location, height and chemistry, saving researchers countless hours in the field and giving environmental conservationists vital information to protect Hawaii’s forests and other natural resources. 

Dr. Greg Asner directs the CAO, a project supported by the Carnegie Institution of Washington. Asner lives part time on the Big Island, and maintains a laboratory at the Institute of Pacific Islands Forestry in Hilo, where he developed the science behind the technology.

The system works its magic by firing a laser through a hole in the bottom of a twin-engine aircraft. As the plane flies over the forest (at roughly 7,000 feet above ground), the laser sweeps back and forth like a broom. Its light bounces off the different levels of vegetation, producing a 3-D image of the entire forest, from the tips of the canopy down to the ground. A hyperspectral imager—or ultra-fancy camera—shows the chemistry of each plant, letting scientists know whether a species is native or invasive and how fast it’s growing. Since CAO’s accuracy is within 50 centimeters, a researcher can note a particular tree’s coordinates and walk right up to it.

An aerial view of the Nanawale Forest Reserve on the Big Island, as seen by the Carnegie Airborne Observatory. Various colors indicate that there are about 15 to 20 species of plants and trees in the area photographed.

image: courtesy Carnegie Airborne Observatory

1 The Nanawale Forest Reserve is made up of mostly native ohia trees. 2 Pink and red colors show highly invasive trees and shrubs, such as guava trees and melastoma (considered a noxious weed), moving from a landowner’s property into the forest reserve. 3 The right half of the landowner’s property is cleared land, while the left half includes some exotic plants.

“Our science explores ecosystems and how they are changing with, say, the introduction of an invasive species or with climate change,” Asner says. “You can use the CAO to map invasive species for containment, or to search for a rare species. [Environmental managers] can make informed decisions on where to put their limited time and money.”

Since January, CAO has been cruising the Big Island skies. The ongoing project—funded by a handful of sources, including NASA, the Hawaii Division of Forestry and Wildlife and the U.S. Forest Service—has provided information on the island’s forest inventory, invasive species and underlying terrain.

Says Asner, “I want people to realize that we need to make some rapid advances in order to take care of what we have left.”

Want to see more images? Find them at cao.stanford.edu.

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Honolulu Magazine January 2020
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