Laser technology used to measure biomass of giant Californian redwood trees

Oct. 15 (UPI) — For the first time, researchers have executed a three-dimensional survey of the world’s biggest trees, using laser technology to precisely measure the volume and biomass of Northern Californian redwoods.

Researchers detailed the feat in a new paper published Thursday in the journal Scientific Reports.

California’s giant redwood trees play an outsized role in above ground carbon sequestration, and have a larger impact on their ecosystems than their more diminutive neighbors.

“They are also very hard to measure and so tend to be underrepresented in measurements and models of above ground biomass,” Mat Disney, professor of geography at University College London, said in a news release.

Researchers used ground-based lasers to measure the biomass of large coastal redwood trees, Sequoia sempervirens, at three forest sites in Northern California. Scientists hope the data will help them more precisely monitor the impacts of climate change on redwood forests.

“Big questions within climate science in response to rising CO2 levels are whether and where more trees should be planted and how best to conserve existing forests,” said Disney, lead author of the new study. “In order to answer these questions, scientists first need to understand how much carbon is stored in different tree species.”

Traditional means for measuring tree biomass require either cutting and weighing trees piece by piece or by scaling up manual measurements — methods ripe for error.

The latest survey allowed scientists to chance to test the laser system that will be deployed on NASA’s GEDI mission, an effort to map forest carbon from space.

The colossal 1,400-year-old redwood known as the Colonel Armstrong tree was among the trees scanned by the GEDI lasers. The tree measures 288 feet tall, more than 11 feet wide and weighs 110 tons.

When researchers compared the laser-based biomass measurements with those made via 3D crown mapping, a more involved, fine-scaled measuring method involving expert climbers, they found the data agreed to within 2 percent.

Scientists suggest future tree survey could combine selective 3D crown mapping efforts with laser-based measurements.

“Estimating the biomass of large trees is critical to quantifying their importance to the carbon cycle, particularly in Earth’s most carbon rich forests,” said co-author and NASA scientist Laura Duncanson.

“This exciting proof of concept study demonstrates the potential for using this new technology on giant trees — our next step will be to extend this application to a global scale in the hopes of improving GEDI’s biomass estimates in carbon dense forests around the world,” said Duncanson, an assistant professor at the University of Maryland.

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