Dead and dying coastal trees drowned by intruding saltwater are giving researchers a new window into how forest ecosystems respond to rising seas — and what that trajectory means for timber-producing coastlines across the globe. That is according to research presented this week at the American Chemical Society’s Spring 2026 meeting in Atlanta, where a University of Delaware team outlined new findings on water cycling through so-called “ghost forests.”
Ghost forests — clusters of bare, bleached trunks left standing after saltwater intrusion kills salt-intolerant trees — are spreading rapidly along the US eastern seaboard. A December 2025 Nature Sustainability mapping study, conducted at the individual-tree level, identified more than 6 million dead trees concentrated in low-lying Atlantic coastal zones, with salinisation, rather than direct flooding, as the primary driver.
The Delaware team, led by undergraduate environmental engineering student Samantha Chittakone, is focusing on stemflow — the rainwater that travels down branches and trunk surfaces into the soil below. Their research tracks how dissolved organic carbon composition shifts as a healthy coastal forest transitions into a ghost forest, using stemflow as a direct tracer of canopy condition and its link to subsurface groundwater chemistry.
“Walking through these coastal forests, surrounded by nature, is beautiful,” Chittakone said. “However, it is disheartening to see the healthy trees becoming less prevalent as you approach the shoreline and the effects of rising sea levels become apparent.”
The commercial stakes are significant. In South Carolina alone, ghost forests now run along beaches, estuaries and tidal rivers — a spread state forestry authorities have flagged as a direct threat to a $23 billion industry. Salt is one vulnerability that the state’s otherwise storm-resilient coastal forests cannot adapt to.
Earlier research by North Carolina State University put a number on the damage. The transition from coastal forest to marsh along the Albemarle-Pamlico Peninsula produced 130,000 metric tonnes of aboveground carbon loss over just 13 years — equivalent, by US EPA calculations, to the annual emissions of roughly 103,000 passenger vehicles. Researchers noted that aboveground carbon decline along shorelines could serve as an early-warning signal for sea-level rise before mature tree mortality even begins.
The phenomenon is far from a North American problem. Similar ghost forest formations have been documented in European and Australian coastal zones, where saltwater intrusion, storm surges, and flooding are compressing geological-scale processes into decades. The USDA’s Climate Hubs programme has found that sea-level rise is raising water tables tens to hundreds of metres inland from tidal boundaries — stressing root systems and converting forested wetlands to standing-water wetlands within years rather than generations.
For the Delaware team, stemflow samples collected from mid-Atlantic sites will be cross-referenced against groundwater dissolved organic carbon tracers to determine how quickly soil chemistry shifts as canopy health declines — a methodology the researchers say can detect forest transition before visible tree death begins. With six million dead trees already mapped along the US Atlantic coast, the detection window is narrowing.
