Hydrology, Cryosphere & Earth Surface Research Spotlight

Impact of Hurricanes and Nor’easters on Coastal Forests

Scientists trace severe storms’ effects through tree ring growth patterns.

Source: Journal of Geophysical Research: Biogeosciences

By Sarah Witman

As climate change continues to make hurricanes and other storms across the globe more frequent, long lasting, and severe, on average, scientists are looking to pinpoint the impacts of these storms on the ecosystems where they occur. In 2017, for example, GPS data of Houston showed a depression in Earth’s crust almost 2 centimeters deep caused by massive flooding from Hurricane Harvey. When Hurricane Irma passed through Florida later that year, it tore up seagrass beds and mangrove forests. And, to some extent, the Gulf Coast is still recovering from wetland loss and erosion caused by Hurricanes Katrina and Rita in 2005.

Coastal regions, where these effects are felt the most, are home to some of nature’s most valuable—and vulnerable—ecosystems. The U.S. Mid-Atlantic coastal region is made up of wetland forests, saltwater and freshwater marshes, bays, and estuaries. Forests comprise about 70% of land cover in the region.

Here Fernandes et al. investigated the impact of hurricanes and nor’easters on coastal pine forests in Virginia. The researchers used annual tree ring data and a mathematical model to analyze the forests’ response to severe storms over the past few decades.

For the most part, the width of the tree rings signified age, regional climate trends, and other effects on the individual tree. In some cases, however, the team found that the rings showed signs of growth disturbances matching up with the timeline of known storms.

Specifically, the team looked at seven examples of severe storms that hit the Virginia coastline between 1904 and 2015: the Chesapeake-Potomac Hurricane of 1933, the Ash Wednesday nor’easter of 1962, the 1998 nor’easter, Hurricane Isabel in 2003, Hurricane Ida in 2009, Hurricane Irene in 2011, and Hurricane Sandy in 2012.

The researchers observed that ring growth declined following the years that these storms occurred. The magnitude of these declines, they found, correlates well with the magnitude of the storm in terms of storm surge height and wind speed. These declines continued for about 3 years after the storm, after which ring growth started to recover.

This study is an interesting look at coastal forests’ response to severe storms, as well as their resilience—something that becomes ever more important as climate change alters the frequency and severity of storms. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1002/2017JG004125, 2018)

—Sarah Witman, Freelance Writer

Citation: Witman, S. (2018), Impact of hurricanes and nor’easters on coastal forests, Eos, 99, https://doi.org/10.1029/2018EO095599. Published on 03 April 2018.
© 2018. The authors. CC BY-NC-ND 3.0