Aerial photographs taken before and after the storm showed researches the extent of forest canopy damage.
When Hurricane Irma hit southern Florida in September of 2017, the storm buffeted coastal mangrove forests with winds over 116 mph – strong enough to rip off leaves, break branches, and snap tree trunks in half. Of the mangrove forest damaged by Hurricane Irma, about 83% recovered after the first year. But the rest didn’t, leaving scientists wondering why some trees didn’t bounce back.
Using NASA data collected before and after Hurricane Irma, researchers found that storm surge and trapped seawater – not wind – ultimately caused the trees to die. Trees survived in places where salty ocean water brought in by the hurricane was able to drain, they write in a paper published June 28 in Nature Communications. But in areas where the saltwater was trapped in low lying areas without enough drainage, the mangroves couldn’t recover. The findings suggest that improving the flow of water near submerged mangroves or flushing them with freshwater could help restore mangroves after a hurricane.
Mangroves have adapted to live along the coast. These forests act as a barrier to protect inland areas and coastal communities during a storm. Some species have a network of above-ground “prop roots” that support the tree while others have roots that look like long fingers poking out of the ground, providing extra support to stabilize the tree and provide oxygen to the root system. These semi-submerged root networks are also an important nursery habitat for fish and other marine species.
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Image via NASA Goddard Space Flight Center
