Mangroves are making a comeback across the world after decades of loss, thanks in part to warming temperatures. Louisiana could benefit from the spread of the rooty aquatic tree, which would provide unique protection against erosion in vulnerable coastal areas.
A new study from Tulane University found that, after deforestation and coastal development in traditional habitats such as southern Florida hit mangrove populations hard, vitally threatened forest ecosystems are now having a renaissance.
“After decades of loss, we’re finally seeing a global turning point for mangroves,” Zhen Zhang, a postdoctoral scholar at Tulane’s School of Science and Engineering and lead author of the study, said in a news release. His work was published this month in the academic research journal Science.
“What we’re seeing now is a real shift. Mangroves are now showing a net increase globally, and the rate of degradation is slowing,” said Daniel Friess, an earth and environmental sciences professor at Tulane and director of its Mangrove Lab.
For his study, Zhang looked at more than 40 years of satellite data to track the growth of mangrove forests worldwide, ending their decline by naturally expanding into new territories. Mangrove forests shrunk nearly 2,900 square kilometers from the 1980s through 2010, but gains in acreage over the past 16 years have reversed the trend.
Louisiana coastal restoration also stands to benefit from becoming a new home for mangrove forests, their resilience showing promise as a “powerful nature-based solution for climate mitigation and coastal protection,” said Zhang.
Mangroves haven’t historically had a large presence in Louisiana, where salt marsh grasses dominate its coast. But species such as black mangrove are naturally moving further north as temperature trends climb, and they are being spread through coastal restoration efforts. Their woven, basket-like root structure can help delay coastal erosion by minimizing wave impacts onshore.
Healthy mangrove forests also store huge amounts of carbon dioxide, keeping the greenhouse gas from entering the atmosphere and contributing to global warming.
“When mangroves are cleared, large amounts of long-stored carbon are released into the atmosphere. But when deforestation stops, mangroves can continue to accumulate carbon naturally over time,” Zhang said. “There’s a major climate benefit in both avoiding emissions now and allowing future carbon storage.”
With the trees moving in, researchers across the state are working to better understand how these new Louisiana residents are changing the coastal environment.
Scientists and students at Tulane’s Mangrove Lab are studying the ecosystem benefits mangroves can provide, including carbon absorption and fisheries habitats.
Louisiana State University researchers and students at the Wetland and Aquatic Biogeochemistry Laboratory are researching how the trees alter the existing Louisiana coastal landscape, from microscopic organisms to entire ecosystems.
“While some mangroves are still being lost, this could make them a rare conservation success story and an important source of optimism for climate action,” said Friess.
