AAAS: “AI reveals vast ‘ghost forests’ along U.S. coast.” Spencer Rhea, an ecologist at Duke University, + colleagues gathered to investigate “ghost forests”—otherworldly stands of bleached dead trees drowned by flooding or poisoned by saltwater that is intruding inland in the Albemarle-Pamlico Peninsula of North Carolina. “They had been led here by a new map of ghost forests, created with the help of artificial intelligence (AI), that identified individual dead trees standing along the east coast of the United States.
Posted as a preprint in May, the map counted millions of dead trees across 36,000 square kilometers of coastal forests, many in areas where ghost forests had not been documented before.” But the aerial view couldn’t show exactly what killed specific stands of trees, which is why, wearing waders, they had to brave the muck + mosquitoes to collect samples. “It is forensics for tree death,” says Duke ecologist Emily Bernhardt, a leader of the NASA-funded project, which in a nod to Dr. Seuss is called THE LORACS, for Tree Health Evaluated using LiDAR, Optical, and Radar Applications across Coastal Systems. Their answers could help identify other forests at risk of becoming ghosts, a process expected to reduce biodiversity and release planet-warming carbon stored in the trees, including root systems.
Henry Yeung, a doctoral student at the University of Virginia (UVA), spent hundreds of hours identifying more than 50,000 dead trees in aerial images of the coastline between South Carolina and Maine.”He then used these hand-labeled trees to train a deep learning algorithm to spot their pale color and the distinctive shadows of their bare branches in other images.” Scanning the images on its own, the algorithm counted nearly 12 million dead trees standing near the coast, as well as other patches of ghost forest farther inland along estuaries. “Not all of the AI-counted trees were killed by water; some were victims of insects or disease.”
Such AI mapping could be extended to identify ghost forests worldwide. “If you’re losing forests in a similar way [to the U.S. east coast],” he says, “then that’s a big chunk of carbon storage.” So—sea level rise [SLR], more intense storms, + infiltration of salt into aquifers all help increase carbon emissions, demonstrating the interaction of multiple climate hazards.
