For some residents of the North Carolina coast, the 2014 Independence Day weekend will be remembered not for fireworks and family cookouts, but for damage assessment and cleanup following the high winds and heavy rain that downed trees when Hurricane Arthur came ashore on July 3.
U.S. Forest Service researchers believe that Arthur did relatively little harm to the state’s coastal forests, but they will continue to watch for delayed impacts of the storm using the satellite imagery-based ForWarn—a forest disturbance monitoring tool which provides maps that compare current vegetation greenness with that of the previous year, the last three years, and the past decade. Of greater concern to the researchers and ForWarn users in North Carolina are the lingering effects of another storm — 2011’s Hurricane Irene.
Irene made landfall over eastern North Carolina on August 27, 2011, and significant flooding followed. About a year later, Rob Trickel, head of the Forest Health branch of the North Carolina Forest Service, saw something peculiar in eastern North Carolina highlighted on a ForWarn map. “In September 2012, I was perusing ForWarn and the Forest Disturbance Monitor*. Since the Pains Bay Fire on the coastal plain the year before, I made it a point to periodically check out that part of the state on ForWarn maps to see how green up was progressing,” says Trickel. “On that day, I noticed an area of disturbance along the sound just east of the Pains Bay Fire. I thought at first, ‘Did I miss that part of the fire?’ before realizing that this was not fire-related.”
Trickel would soon travel to a meeting on the coast, so he made plans to check out the area in person. Meanwhile, his investigation continued. “I went back and looked through the ForWarn map archives because I knew this place to be a grassy, scrubby area with scattered pond pines, swampbay, and red maple and other hardwoods,” says Trickel. Based on the ForWarn maps, the greenness of the vegetation appeared to have started declining a year earlier, in September of 2011. “When I realized this, I hypothesized that the disturbance was related to saltwater storm surge from Hurricane Irene.”
While driving to that meeting, Trickel and another NC Forest Service staff member observed the disturbance highlighted on the ForWarn maps firsthand. “We saw classic signs of salt damage. Many of the pines and hardwoods were dead and had already lost their leaves. Leaves on trees that were clinging to life were off-color. The scrubby understory was a mixture of living and dead shrubs and grasses,” remembers Trickel. “After talking to some locals who said the area was inundated with water after Irene, there was no doubt that this was salt damage that could be traced back to the storm surge from the hurricane.” Today, according to Trickel, most overstory trees in this area are dead, their leaves gone and bark sloughing off. Though these coastal North Carolina forests may eventually recover, they might require the assistance of land managers along the way.
This particular example of disturbance demonstrates not only the power of weather and climate in shaping forests, but also the power of online tools and relationships that make remote monitoring of forests possible. Steve Norman, a research ecologist with the Forest Service Eastern Forest Environmental Threat Assessment Center, has been using ForWarn to watch vegetation in areas hit by wildfire and hurricanes. “What I find remarkable is how well we can track the post-disturbance response from space, and how it differs from recent fires or other past hurricanes,” he says. “Sites like these coastal forests are particularly important to monitor over the long term because they are vulnerable to sea level rise, hurricanes, and wildfire. New technologies like ForWarn and information sharing through a network of users and land managers on the ground can help with that.”
ForWarn is a collaborative effort involving multiple federal and university partners. Learn more about the ForWarn assessments of the Pains Bay Fire and Hurricane Irene disturbances. For more information, contact Bill Hargrove, Eastern Threat Center research ecologist and ForWarn project director, at firstname.lastname@example.org.
*The Forest Disturbance Monitor is a complementary tool developed by Forest Service Forest Health Protection. Visit the Forest Health Protection Mapping and Reporting Portal to learn more.