As sea levels continue to rise, coastal areas face threats of submersion and increasing salinity. To assess this disequilibrium (when ecosystems are not aligned with the conditions they are experiencing), a multidisciplinary team of scientists including researchers from the Yale School of the Environment evaluated the resilience of mangroves in the Florida Everglades. They found a surprising result — the disequilibrium could increase carbon capture over the next century as scrub mangroves expand inward, amounting to a 12%, increase (131 metric tons) of carbon annually.
The findings, published in the Journal of Environmental Management, could help inform best management practices for future conditions and improve our understanding of the importance of transitioning fresh water ecosystems to more saline environments, noted Sparkle Malone, assistant professor of ecosystem carbon capture at YSE and member of the scientific leadership team at the Yale Center for Natural Carbon Capture who coauthored the study.
“We expect that mangroves will need to continue moving further inland. If this occurs, it could enhance carbon capture in those new locations. We must ensure that we provide adequate space for them to transition and avoid creating barriers that would hinder their movement into these areas,” she said.
The study, conducted in partnership with the Florida Coastal Everglades LTER program based at Florida International University’s Institute of Environment, examined three specific ecosystems: a grassy area called a marl prairie; a mixed zone of freshwater and saltwater known as an ecotone; and a type of wetland characterized by salt tolerant trees called scrub mangroves. In their analysis, the researchers introduced the concept of “climate debt,” which is the difference between the current state of an ecosystem and its optimum state if it were fully adapted to new environmental conditions.
“When predicting the impact of sea-level rise and climate change on these ecosystems, one might assume that they are under the most stress and at high risk of decline. However, when we examine how these ecosystems are responding to the changing conditions, then predictions look very different,” Malone said.
Newsletter
Biweekly, we highlight three news and research stories about the work we’re doing at Yale School of the Environment.
The researchers discovered that the ecosystems are responding differently to rising sea levels. Scrub mangroves continue to be effective in absorbing carbon even as water levels increase. In contrast, marl prairie and ecotone systems exhibit a decline in carbon sequestration, with marl prairie experiencing the greatest climate debt due to limited ability to adapt to higher water levels.
The findings highlight the need to tailor management practices to the specific needs of each ecosystem type as part of ongoing efforts to restore the Everglades, the authors note.
"Restoring freshwater systems is very important and will continue to be essential. However, as we consider the changes that will result from rising sea levels, we must ensure that our efforts to restore freshwater systems align with the necessary adaptations along the coastline,” Malone said. “This may mean that some areas need to transition to more saline ecosystems. What was once seen as a sign of poor restoration may, in the future, be viewed as a positive step towards restoration. This represents a significant change in mindset," Malone said.
