Seeing the forest in a brand new way

BLUE RIVER — Scaling a 280-foot Douglas fir in the H.J. Andrews Experimental Forest, biologist Matthew Betts can spot evidence of the animals that depend on the old-growth tree, from the arthropods that burrow into the bark to the woodpeckers that dig them out.

He and the professional tree-climbers on the site last week use a system of ropes, harnesses, carabiners and other equipment to inchworm their way up to the canopy, where earlier the climbers had dropped a tape measure to size up the tree.

But measuring the exact height of a tree, and counting the layers and extent of the branches that provide habitat, is a labor-intensive endeavor.

"It just takes an incredible amount of time," said Betts, an assistant professor of landscape ecology with Oregon State University. It could take 15 minutes to measure one tree, he said.

But using a growing technology that involves shooting lasers from airplanes to accurately and quickly create three-dimensional maps of the ground and vegetation below, Betts and other researchers are discovering more about the forest ecosystems in Oregon.

"It allows us to see the forest in new ways," said Thomas Spies, a research forest ecologist with the U.S. Forest Service's Pacific Northwest Research Station.

While in oceanography, it's hard for researchers to figure out what's on the deep ocean floor, he said, in forestry it's the opposite — scientists need to know more about the canopy. And the new technology, called "light detecting and ranging," or LIDAR, will help them get a more detailed picture of life 250 feet up above the forest floor, without the need to scale individual trees.

LIDAR involves flying over areas in aircraft with specialized equipment that can shoot thousands of pulses to cover the forest.

"It creates basically a rain of laser pulses," Spies said.

The pulses travel until they hit something — whether it's the top of a tree, lower branches, shrubs below or the bare ground — and then they bounce back up to the plane. By calculating how far the pulses traveled, the equipment can determine the shapes and sizes of the area below.

"It's like draping a very light cloth across a canopy," Spies said. The cloth would catch on the peaks of the canopy, but fall down into the gaps between branches and vegetation as well.

So through the LIDAR mapping process, researchers can get a three-dimensional portrait of the forest. Over large areas like the 15,000-acre Andrews Experimental Forest, LIDAR costs about $2 per acre.

And with those maps in hand, scientists can start asking questions that would have been difficult to investigate previously.

Betts, for example, has worked on identifying bird habitat based on the structure of the forest layers. Once researchers know which types of habitat birds favor, they can use LIDAR to see how much of that habitat exists within a forest and make estimates of the bird population.

And they can also track how much habitat is lost for specific species over time, Betts said.

LIDAR also could be useful in helping to take detailed measurements of trees in spotted owl habitat, he said, and then making predictions about where other owls could be either currently or in the future.

"Often the assumption is that all old growth is spotted owl habitat," he said. "But all old growth isn't equal."

LIDAR also could be used to estimate how much carbon the trees in a forest contain, Spies said, as people consider the value of forests in storing greenhouse gases.

"There's a lot of interest in understanding when, where and how much carbon is stored in forests of different kinds," he said, noting that not all types of trees will store the same amounts of carbon.

Or forestry researchers can use the technology to spot where trees are growing the tallest, and then identify what kinds of growing conditions can lead to the biggest trees, Spies said. In Central Oregon, the Deschutes National Forest and other agencies have been working together to hire contractors to map much of the national forest, along with other areas, said Helen Maffei, forest health specialist with the national forest.

"We'll have most of the forest done by the end of next summer," she said.

For her, the excitement is that the LIDAR images can provide that three-dimensional map of large areas.

"It's pretty cool," she said. "It can give you better ideas, and more detailed images, of the ground and topographic features."

LIDAR could show forest specialists where there are areas that are prone to landslides, or where roads need to be repaired, she said.

And Maffei said she's hoping to be able to map the biggest trees on the forest — something that previous mapping techniques have not had the resolution to reveal.

"Especially the really ancient ones that we call relic trees, those are the ones that spotted owls seem to be really interested in," she said.

Knowing where the tallest of the tall trees are could help the forest determine where to locate timber projects, or where to prioritize firefighting efforts, she said.

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