The best of EcoWatch, right in your inbox. Sign up for our email newsletter!
Amazon Mangroves ‘Twice as Carbon Rich’ as Its Rainforests
By Daisy Dunne
The vast mangroves of the Amazon store twice as much carbon per hectare as the region's tropical forests, new research shows.
The relatively understudied ecosystem also stores 10 times more carbon than Amazon savannahs—a type of grassy plain with sparsely populated trees, according to the study.
However, the wetlands face threats from deforestation and climate change, the researchers say. Introducing more measures to protect mangroves will be key to preserving its large carbon store, they add.
The findings provide "yet more evidence of the extraordinary carbon stocks found in mangroves" worldwide, another scientist told Carbon Brief.
The Amazon is well known for its 167m hectares of rainforest, but is less known for being home to close to 1m hectares of "mangrove" forests.
Mangroves are trees and shrubs that grow in coastal waters across the tropics and subtropics. They are most easily recognized by their tall protruding roots, which they use to anchor themselves against incoming tides.
The new study, published in Biology Letters, is the first to make an on-the-ground estimate of how much carbon is stored in the Amazon's vast wetlands.
It finds that, on average, Amazon mangroves store 511 tonnes of carbon per hectare—roughly double that of the region's rainforests. Writing in their research paper, the authors said:
"The carbon stocks of the Amazon mangroves were over twice those of upland evergreen forests [rainforests] and almost 10-fold those of tropical dry forest [savannahs]."
For the study, the researchers visited nine mangroves—along with three salt marshes (a type of coastal grassland)—within the Brazilian Amazon.
At each site, they took measurements of the amount of carbon stored "aboveground," in the trees and fallen leaf litter, and "belowground," in the roots and soil.
To measure carbon stocks, the researchers measured changes to "biomass"—the weight amassed from the production of new leaves and shoots, or the thickening of a tree trunk, for example.
Plants take in CO2 from the atmosphere during photosynthesis and later use it to build and extend their trunks, stems and roots. Because of this, measuring changes to biomass gives scientists an idea of how much carbon is being stored in a given area over time.
The researchers then compared their estimates to previous data on carbon storage in the Amazon rainforest.
The chart below shows the average amount of carbon stored in tonnes per hectare by Amazon mangroves (far left) and Amazon rainforests (second left). The charts also include results from the salt marshes (second right) and data taken from a previous study by the researchers undertaken in desert-like "Caatinga" and savannah-like "Cerrado" ecosystems.
On the chart, green shows the results for aboveground carbon, brown shows the results for shallow belowground carbon and black shows the result for deep belowground carbon. (Rainforest soil tends to be shallow and nutrient-poor, while deep deposits of soil can build up in mangrove forests.)
Estimated carbon stock in tonnes per hectare in Amazon mangroves and forests, "Caatinga" (desert-like) mangroves and forests, salt marshes and "Cerrado" (savannah) ecosystemsBoone Kaufmann et al. (2018)
The results show that, on average, Amazon mangroves store around twice as much carbon per hectare as Amazon forests.
The majority of the carbon stored by mangroves is held in the soil, the research shows. Wetland soils tend to be carbon-rich because they are waterlogged, which slows the rate at which plant matter decomposes.
When decomposition is slow, carbon-rich materials are able to build up, explained Dr. Mark Spalding, a marine scientist and honorary fellow at the University of Cambridge, who was not involved in the study. He told Carbon Brief:
"The soils are very carbon rich. This is because they are permanently waterlogged and, so, carbon doesn't break down. Freshwater peats have similar soil carbon concentrations."
The tightly-packed nature of mangrove trees also enhances carbon storage in comparison to forests, which tend to be more sparse, he added.
The results suggest that protecting the Amazon wetlands could play a larger role in slowing climate change than previously thought, the authors say.
Amazon wetlands are currently threatened by deforestation—often to make way for fish farming—as well as rising temperatures, which could cause wetlands to dry out by increasing rates of evaporation. In their research paper, the authors said:
"The vast extent of Brazilian mangroves coupled with the large quantities of greenhouse gas emissions that results from deforestation underscores their potential value in climate change mitigation."
The findings provide evidence of the "extraordinary carbon stocks found in mangroves," Spalding said, but a key question remains about how stable this carbon is:
"Whether this carbon is short-lived or whether a significant proportion is being buried for the long-term in offshore sediments is a very important research question."
Reposted with permission from our media associate Carbon Brief.
- India lost 40% of its mangroves in the last century. And it's putting ... ›
- Mangrove Restoration and Rehabilitation for Climate Change ... ›
EcoWatch Daily Newsletter
‘Companies Should Not Be Allowed to Use Hazardous Ingredients in Products People Use’: Michelle Pfeiffer Speaks Up for Safer Cosmetics
The beauty products we put on our skin can have important consequences for our health. Just this March, the U.S. Food and Drug Administration (FDA) warned that some Claire's cosmetics had tested positive for asbestos. But the FDA could only issue a warning, not a recall, because current law does not empower the agency to do so.
Michelle Pfeiffer wants to change that.
The actress and Environmental Working Group (EWG) board member was spotted on Capitol Hill Thursday lobbying lawmakers on behalf of a bill that would increase oversight of the cosmetics industry, The Washington Post reported.
By Julia Conley
Scientists at the United Nations' intergovernmental body focusing on biodiversity sounded alarms earlier this month with its report on the looming potential extinction of one million species — but few heard their calls, according to a German newspaper report.
The climate crisis is a major concern for American voters with nearly 40 percent reporting the issue will help determine how they cast their ballots in the upcoming 2020 presidential election, according to a report compiled by the Yale Program on Climate Change Communication.
Of more than 1,000 registered voters surveyed on global warming, climate and energy policies, as well as personal and collective action, 38 percent said that a candidate's position on climate change is "very important" when it comes to determining who will win their vote. Overall, democratic candidates are under more pressure to provide green solutions as part of their campaign promises with 64 percent of Democrat voters saying they prioritize the issue compared with just 34 percent of Independents and 12 percent of Republicans.
President Donald Trump has agreed to sign a $19.1 billion disaster relief bill that will help Americans still recovering from the flooding, hurricanes and wildfires that have devastated parts of the country in the past two years. Senate Republicans said they struck a deal with the president to approve the measure, despite the fact that it did not include the funding he wanted for the U.S.-Mexican border, CNN reported.
"The U.S. Senate has just approved a 19 Billion Dollar Disaster Relief Bill, with my total approval. Great!" the president tweeted Thursday.
"There was a lot of devastation throughout the state," Governor Mike Parson said at a Thursday morning press conference, as NPR reported. "We were very fortunate last night that we didn't have more injuries than what we had, and we didn't have more fatalities across the state. But three is too many."