Michelle So, Contributing Photographer

Researchers from the Yale School of the Environment recently published a paper in the Global Change Biology on mangrove forest resilience to natural disasters such as hurricanes.

Mangroves are a type of tropical forest found in coastal regions such as the Everglades of Florida. They are often the first barrier of defense when tropical storms or hurricanes come into an area.

“We found that mangroves initially lost carbon, both from high respiration rates and also reduced amounts of photosynthesis due to hurricane damage,” Dr. David Reed, associate research scientist at the Yale School of the Environment, said about the study. 

The ability of a forest ecosystem to recover after a hurricane is highly dependent on how it is able to transfer the energy from what it intakes into energy. 

Just like humans and animals, plants also breathe and respire, taking in oxygen and breathing out carbon dioxide. Plants, however, have the ability to remove that carbon through photosynthesis, turning gaseous wastes into usable and storable sugars and nutrients. 

The difference in carbon taken in by a plant and carbon lost via respiration is known as net carbon exchange.

Net carbon exchange is “at a very simple level, is a measure of the land surface breathing,” said Reed.

Greener, more vegetated ecosystems that have higher rates of photosynthesis and lower rates of respiration absorb more carbon dioxide than they produce. These are known as carbon sinks.

“Generally, the quicker the forests recover, the quicker they can recover their abilities to promote ecosystem services, not only like sequestering CO2 from the atmosphere, but also buffering storm surge, among others,” Tiffany Troxler, an associate professor in the department of earth and environment at Florida International University, said.

Intuitively speaking, rates of photosynthesis are controlled by how much leaf surface area a tree has; the greater the green, the quicker the photosynthesis. 

However, high-speed winds in hurricanes could damage the trees, reducing the leaf area and undermining their photosynthetic ability. The mangrove study monitored the canopy leaf cover area before and after a storm. The defoliation as a result of the hurricane landfall events was significant.

However, “mangroves are resilient and can recover quickly, and we found that after four years the ecosystem is back to where it was before the hurricane landfall,” Reed said.

According to Reed, mangroves are relatively large carbon sinks compared to other ecosystems. Although mangroves don’t take up much physical space — about 57,000 square miles of mangrove remain on the planet — they serve an important role in the global carbon cycle.

Liza Comita, the Davis-Denkmann professor of tropical forest ecology and co-director of the Yale Center for Natural Carbon Capture, wrote to the News regarding the importance of mangrove conservation.

“Mangroves are ecologically and economically important ecosystems: they provide protection from storms and flooding, store carbon, and serve as nursery grounds for fisheries,” Comita said.

She added that the Environmental Leadership and Training Initiative at Yale is currently developing an online course titled “Mangroves: Conservation, Sustainable Use, and Restoration” to provide knowledge and guidance for practitioners from around the world.

Troxler emphasized the importance of this science, as conservation of the mangroves is crucial to ensuring these coastal buffers remain in place.

“Hurricane season is often a stressful time… [and] we’ve been lucky for some time here in Miami where we haven’t had anything over a category four hurricane since 1992,” Troxler told the News. “Conserving and protecting existing mangroves and recovering mangrove forests where they’ve been lost can help reduce the impacts of these powerful storms.”

Troxler currently works with the Intergovernmental Panel on Climate Change, or IPCC, on their national greenhouse gas inventories. By monitoring greenhouse gas emissions from various countries, the IPCC is able to craft policy accordingly to prevent exceeding limits and reinforce emission regulations.

The study, Troxler says, is important in “this policy context” in that it provides crucial information about what ecosystems are more resilient to impacts of extreme events, such as the Everglades mangroves are to hurricanes.

The Everglades National Park was founded on Dec. 6, 1947.