UCLA-led research examined records dating to 1700s to discover how mangroves expand and retreat with climate cycles.
Mangroves are tropical, salt-tolerant trees that grow in the intertidal zone of coastal waters. They don’t tolerate cold weather, particularly extreme freezes, during which they die and get replaced by coastal salt marshes.
In the 1980s, a series of freezes caused the most recent major die-off of Floridian mangroves (and citrus crops, which also fare poorly in cold weather). Since then, previous research showed, mangroves have flourished and expanded further from the tropics. As global temperatures continue rising, noting where mangroves and similar trees and vegetation flourish can serve as a marker to monitor the effects of climate change.
A new study led by UCLA’s Kyle Cavanaugh of how Florida’s mangroves and salt marshes are affected by changes in climate, both man-made and natural, illustrates the complex interplay between our changing climate and living natural systems.
The paper, which was published in PNAS, found that decades-long, natural climate cycles have determined the northern extent of Florida mangroves for at least the past 250 years. Freeze events that took place approximately every 10 to 30 years caused die-offs, during which mangroves were replaced by salt marshes until warmer trends spurred regrowth.
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Image via NOAA