Tree damage due to Hurricane Sandy
Wikimedia Commons

Hurricane Sandy turned many East Coast forests into tree graveyards overnight, but one study says that removing them all may not be a good idea.

New Jersey and New York lost thousands of trees to Hurricane Sandy. “They were uprooted, they were snapped,” says Lawrence Hajna, a press officer at the New Jersey Department of Environmental Protection. State parks “focused on removing any hazardous trees that would impact public areas” including trails and visitor centers, he adds. Trees not in the way were largely ignored.

However, the fate of broken non-hazardous trees on private land is more variable. If past storms are any indication, these trees are likely destined for the axe for cleaning purposes. But “the forest does not need us to clean,” says Audrey Barker-Plotkin, an ecologist at Harvard and author on the study. And will “probably recover more quickly and less dramatically if we leave it alone.”

In 1938, the “Great New England Hurricane” swept through New England devastating major forests. The largest post-hurricane cleanup effort in United States history was organized. In the years following, the ecosystem struggled to recover and its problems were studied.

The hurricane was initially blamed for these issues, says Chris Peterson, a plant biologist at the University of Georgia unrelated to the study. However, the investigations back then were one-sided, with no pre-storm measurements to compare with the post-hurricane landscape, notes Barker-Plotkin.

Curious about how forests respond naturally to hurricanes like 1938, researchers set up their own hurricane. It was truly a “unique” experiment in terms of the forest area affected and the long-term aspect, says Peterson.

A two-acre forest patch was identified for the tree slaughter and pre-disturbance measurements were taken: tree counts, species identification, and soil measurements. Then came the truck, cable, and winch. Cables were attached to trees and pulled in a northwesterly direction, reflecting the 1938 damage patterns.

Approximately 80 percent of the forest canopy was damaged across the experiment site. Specifically, 276 trees were toppled over, and those trees then partially damaged an additional 325 trees during their fall. An adjoining forest area was left untouched and served as a control site.

Following the “pulldown,” researchers expected the collapsed trees would die immediately. But the trees were stubborn, producing new leaves up to four years following the disturbance, reports the new study in the journal Ecology. Pre- and post-experiment soil measurements revealed carbon and nitrogen systems were unaffected by the artificial hurricane.

Keeping the damaged trees untouched “was really important because it helped the forest system keep a level of production…preventing things like nutrients from leaking out of the soil,” says Barker-Plotkin.

Total biomass levels on the disturbed site also recovered quickly. “We think [these levels] will probably be back to pre-disturbance amounts by year 30 [2020],” says Barker-Plotkin. However, it will take much longer for the experiment site growth levels to catch up to the control site, explains Barker-Plotkin.

Researchers were fortunate that no natural storms disturbed their experiment. If a storm were to sweep through, Barker-Plotkin expects the experiment site would fare better than the control. Older trees are more susceptible to being blown over than younger, shorter trees, reported researchers.

Tree growth was faster in the first few years following the disturbance, says Barker-Plotkin, and then slowed down. The type of trees driving forest growth also changed over time, observed researchers. At first, young trees drove growth. After five to ten years, the older trees took over.

Barker-Plotkin admits the study results are less relevant for managing urban tree environments and more for large private and public woodland properties. Around 64 percent of New Jersey woodland (over 1.3 million acres) and more than 80 percent of New York forest (over 14.8 million acres) is privately owned.

On those properties, clearing away broken trees and converting them into usable timber, called “salvage logging,” is a real moneymaker and commonplace. Besides money, cleanup efforts are driven by people’s perception of damage. Often private landowners opt to clear fell trees to prevent “waste,” says John Scanlon, Massachusetts Division of Fisheries and Wildlife manager and unrelated to the study.

But waste is a matter of perspective, says Scanlon. Damaged forests still provide diverse communities to wildlife, adds Scanlon. “In nature, nothing goes to waste.”

Tags: Environment, forests, hurricane damage