Ecologists and partners at the U.S. Forest Service published new findings on how planted mangroves can store up to 70% of the carbon stock compared to the carbon stock in intact stands after just 20 years.
Researchers have long known that mangroves are superstars at carbon absorption and storage. But until now, there was limited information about how long it took for the carbon stored in planted mangroves to reach the levels found in intact mangroves.
“About a decade ago, Sahadev Sharma, then at the Institute of Pacific Islands Forestry, and I discovered that 20-year-old mangrove plantations in Cambodia had carbon stocks comparable to those of intact forests,” says Rich MacKenzie, also of the Institute of Forestry on the Pacific Islands.
MacKenzie and Sharma assembled a team of mangrove researchers from around the world to lend their expertise. Led by Carine Bourgeois of the Forest Service’s International Programs office, the team used logistical models compiled from 40 years of data and constructed from nearly 700 planted mangrove stands worldwide to measure carbon stock. They found that after twenty years the trees’ carbon stock reached 71-73% of that in intact stands.
These research results could positively impact efforts to restore mangroves worldwide. Together with historic losses, human-induced land use changes, extreme weather events and erosion have wiped out 35 percent of the global mangrove area over the past five decades.
“As our dataset grows and more data becomes available, we hope that researchers and stakeholders will gain new insight into mangrove restoration planning and techniques,” said Sharma.
Part of that research work also includes monitoring mangroves to see how they are doing.
“Periodic and regular monitoring of mangroves can provide useful data on survival and success of restoration efforts and can help develop adaptive management strategies where and when necessary,” said Rupesh Bhomia, from the Center for International Forestry Research and World Agroforestry (CIFOR-ICRAF), declared.
It is increasingly recognized worldwide that the conservation and restoration of mangroves is essential. These trees are not only carbon storage powerhouses, but also coast guards that act as barriers during tsunamis and storm surges. Mangroves also provide habitat for various species and nurseries for many aquatic animals.
But MacKenzie warns that mangrove plantations are not always a solution for tree recovery.
“Well-planned and implemented mangrove plantations are more effective at restoring carbon stocks than degraded stocks. However, this does not mean that mangrove plantations are always the best restoration method,” said MacKenzie.
Planting mangroves does not replace nor compensate for the maintenance of intact stands, the researchers emphasized.
“Our models indicate that replanting in all highly recoverable mangrove areas would absorb less than one percent of annual global emissions over a 20-year period. Therefore, preserving existing mangrove stands is paramount,” Bourgeois stressed.
