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Giving foresters wings: Stephen Logan is working to advance unmanned aerial system technology

Looking up from the road, a stand of pine trees may look healthy as they tower over the rusty soil. 

But a view of the trees from a different angle reveals a different story: A swath of needles the color of the soil that are embedded deep among the healthy trees. The infestation of beetles couldn’t be caught without some serious boots-on-the-ground investment—or, it could be caught in minutes using an unmanned aerial vehicle, or UAV.

Stephen Logan“We had been doing a lot of work with satellite imagery. It’s got pretty good resolution, but it’s nothing close to what UAVs can do,” says Stephen Logan (BSFR ’98, MS ’05), forest certification and quality assurance group manager with F&W Forestry. The international company handles all aspects of forestland management, and for more than a decade Logan has worked to keep the company’s technology on the cutting edge to assist landowners.

“So, our first benefit (to using UAVs) was getting high-resolution imagery of the property we’re managing,” adds Logan. “The second was up-to-date data, because a satellite image is often a year or more old. Or, you pay several thousand dollars to task a satellite to fly over and take imagery.”

Today, technology is making inroads in forest management through many fronts, including UAVs. Just as we apply it to make our lives easier through tracking packages or setting reminders, technology is also making the lives of landowners and foresters easier by calculating harvested area, confirming protection of wetlands in relation to harvest areas or even identifying potential beetle damage before it’s visible.

When Logan first graduated from Warnell, drone technology was not part of a forester’s toolbox. In fact, mapping and GIS classes were just beginning.  When he came back to the University of Georgia for his master’s in forest biometrics, though, the idea was more of a reality. Since then, Logan has stayed on the forefront by developing new ways to incorporate the high-resolution imagery and spatial analysis into forest management.

A map showing four ways an area is imagedGetting high-resolution photos is only the beginning, Logan says. Today, in addition to training new UAV pilots around the world for F&W, Logan also researches ways to add value to the images they’re collecting. For example, he is now flying UAVs with multispectral image capabilities, such as near-infrared technology, to combine visible and invisible portions of the electromagnetic spectrum into images that tell more of the story under the canopy.

“You can create NDVI—normalized difference vegetation index—and you can tell the difference in chlorophyll levels in foilage. One thing we found that’s been really helpful is when there’s been insect damage—we can fly those areas and detect the beetle infestation before you can see it with your eyes,” he says. “That’s something we couldn’t have done before, period. That’s been helpful when the trees are stressed.”

Logan is now working to advance the technology to perform tree counts. By combining high resolution imagery, multispectral data and machine learning, he and partner companies are working to create programs that can identify trees and their height from overhead.

If a forester’s time spent cruising can be augmented with remotely sensed information such as tree counts and heights, says Logan, it reduces field time while potentially increasing accuracy—a win for all involved.

“When this first got going, I was working with open-source technology to try and figure out how the technology could benefit us in forest management because the shortcomings using planes and satellites were obvious,” says Logan. “So, once UAVs started to take hold and become available for commercial use, we were poised to take advantage of this new tool, and it has just grown from there.”

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