In the spring of 2017, NASA researchers flew over the Florida Everglades and Puerto Rico to measure how mangroves and rainforests grow and evolve over time. Five months later, hurricanes Irma and Maria tore through those study areas, creating a unique opportunity to investigate the devastating effects of storms on these ecosystems and a window into their gradual recovery.
In early December 2017, a research team flew over the Everglades and found that an estimated 60 percent of their mangrove study areas were heavily or severely damaged. In late April 2018, the team will return to Puerto Rico to conduct an airborne survey of the rainforests there to quantify the damage and identify sites vulnerable to landslides.
These photos of southeastern Florida reveal swaths of leafless trees, broken branches, and uprooted mangrove trees. The images, which show the Ten Thousand Islands mangrove ecosystem, were acquired on March 28, 2017, and December 1, 2017 by the Goddard Lidar, Hyperspectral and Thermal Imager (G-LiHT).
“It is staggering how much was lost. The question is: which areas will regrow and which areas will not,” said Lola Fatoyinbo, a remote sensing scientist at NASA’s Goddard Space Flight Center. “This is an opportunity. With all these data, we can really make a difference in understanding how hurricanes impact Florida’s mangrove ecosystems.”
The research project was originally designed to examine how freshwater ecosystems, such as sawgrass marshes, are transitioning to saltwater ecosystems. Such changes, which can result from sea level rise and coastal erosion, can affect soil microbes, vegetation, and even the aquifers that Miami draws from for its drinking water.
The team of scientists worked with local land managers—including staff at the Everglades National Park and Florida Fish and Wildlife—to plan data-collecting flights with G-LiHT, which combines high-resolution photographs with a lidar to measure the height and health of vegetation. They twice surveyed roughly 1,300 square kilometers (500 square miles) of southern Florida wetlands.
The scientists also have been using Landsat data to measure the extent of hurricane damage to forests in Florida and Puerto Rico over the past 30 years—particularly areas where vulnerable forests have been or could be replaced by open water. Landsat can provide immediate views of storm damage, while the 45-year archive of Landsat imagery can also show forest destruction and recovery over time.
“We want to know how fast this transition is happening,” said David Lagomasino, a remote sensing scientist at Goddard. “Combining the spatial changes measured by satellite with the structural information we measure from the air, we can estimate where the key habitats are that are most vulnerable.”
“We had this amazing dataset; then the hurricane went through,” Lagomasino added. Hurricane Irma swept through the Everglades National Park on Sept. 10, 2017, with winds of 140 miles (225 kilometers) per hour. “Hurricanes are a natural part of the ecosystem, and we know that the ecosystem does return for the most part. But not 100 percent.” When mangrove trees are destroyed and do not recover, neighboring ecosystems often face an increased risk from storm surges and saltwater intrusion.
In their preliminary analysis, Fatoyinbo, Lagomasino, and colleagues found large gaps in the canopy with snapped branches and uprooted trees. In hardest hit areas, G-LiHT found that the average height of the forest canopy was shortened by 1 to 1.5 meters (3 to 5 feet). The team now plans to compare data sets from before and after the hurricane to see how the areas that were under stress before the storm (from development and saltwater encroachment) recover, if at all. Lagomasino also intends to examine damage patterns and to estimate tree mortality.
NASA images by the Goddard Lidar, Hyperspectral and Thermal Imager (G-LiHT) science team. Story by Kate Ramsayer, NASA’s Goddard Space Flight Center.