Researchers Trace Ancient Cypress Threats as Tree Decline Spreads

An ancient coastal forest in North Carolina and declining trees across Pennsylvania and New York illustrate different pressures on forest ecosystems, from saltwater intrusion to invasive pests and disease. Research published in a new preprint documents at least 871 years of tree growth at Smith Creek, where scientists are investigating threats to bald cypress trees.

According to Coastal Review, the oldest documented tree in the Wilmington area stands within a Smith Creek forest connected to the Cape Fear River. Researchers warn that prolonged saltwater exposure could eventually kill the ancient trees, transforming forested wetlands into marshland.

The study, led by Madison Gerdes, a master's student at the University of North Carolina Wilmington, used tree-ring records to reconstruct environmental conditions over centuries. The findings have not yet undergone peer review.

Researchers extracted narrow wood cores using an increment borer, which removes a thin cylinder without killing the tree. By matching patterns of wide and narrow rings across multiple trees, they established a chronology spanning 871 years. The oldest sampled tree, identified as SMC012, could be older because researchers could not reach its center, likely due to a hollow trunk.

Gerdes described the scientific value of the records in revealing environmental history.

"We can do this kind of environmental storytelling with these trees," said Madison Gerdes, the study's lead author.

Forest ecologist Monica Rother, who advised the research, said the findings establish a significant record for the region. Fifteen sampled trees were more than 500 years old.

"These are the oldest scientifically dated trees in the Wilmington area," said Monica Rother, a forest ecologist at the University of North Carolina Wilmington.

An analysis covering 675 years identified repeated periods of suppressed growth, including episodes associated with drought and low precipitation. Researchers found that unfavorable conditions sometimes affected all sampled trees simultaneously.

Gerdes said the trees' long history of surviving environmental pressures makes the latest threat particularly concerning.

"Look at everything that they have endured, but now they're facing this new threat from saltwater intrusion and humans," said Madison Gerdes.

Bald cypresses tolerate more salt than many trees in southeastern tidal freshwater wetlands, but that resilience has limits. Their canopies provide wildlife habitat, while the wetlands store carbon and help reduce flooding and storm impacts.

Gerdes emphasized the forest's dependence on its dominant tree species.

"The bald cypress are the forest. Without the cypress there is no forest environment," said Madison Gerdes.

Rother said a shift from forested wetland to marsh would not eliminate ecological value, although some functions associated with trees would be lost.

"Both of those systems have value to them," said Monica Rother.

Rother also distinguished the ecological roles of the two environments.

"But there are things that trees provide that a marshland wouldn't," said Monica Rother.

Farther downstream, researchers have already documented a transition toward ghost forest conditions. Sediment evidence suggests salinity had increased by the mid-20th century, and saltwater levels may have become stressful for trees by the 1960s.

Tree-ring records from the downstream site show increasingly frequent and prolonged growth suppression. The latest documented period extended from 1985 through 2022. Researchers linked the decline to prolonged saltwater exposure, with relative sea-level rise and decades of dredging in the Cape Fear River contributing to changing tidal conditions. They could not determine the individual contribution of each factor.

Rother said repeated stress could eventually prevent trees from recovering.

"There must be a threshold where if the trees are suppressed too often and for too long, then eventually they'll die," said Monica Rother.

The upstream stand remains relatively healthy, but researchers are monitoring recent growth slowdowns. They have not established whether rising salinity is responsible, and vulnerability may vary with tree age and growing conditions.

Gerdes expressed concern about whether the oldest trees could withstand the changing environment.

"It's a little scary to be like, look at everything that they can survive, but maybe not this," said Madison Gerdes.

Elsewhere, a report published by River Reporter on October 13 described visible tree decline affecting autumn foliage in its coverage area. The article identified emerald ash borer infestations, beech leaf disease and tar spots on silver maple leaves as three distinct issues affecting local trees.

The emerald ash borer attacks ash trees through larvae that feed within them, disrupting their ability to transport water and nutrients. Some landowners and loggers harvested ash trees before severe deterioration left the standing wood spongy and of little practical use.

Beech leaf disease, caused by a microscopic foliar nematode, damages developing leaf buds. Infected leaves develop dark stripes, turn brown and curl. According to River Reporter, affected saplings can die within one or two years, while larger beech trees may take five to 10 years to die. The disease has been found throughout Pennsylvania and in surrounding New York counties.

Silver maples showing tar spots present a different problem. The spots can alter autumn leaf appearance, but the report noted that they do not threaten the trees' overall health.