The threat posed by the development of rice and palm oil plantations to mangroves in Southeast Asia has been underestimated, according to a study appearing in the Proceedings of the National Academy of Sciences.
According to the research, rice and oil plantations accounted for 38% of mangrove deforestation between 2000 and 2012.
Mangrove forests provide fuel and food for coastal communities, along with being important carbon sinks and rich in biodiversity.
“Aquaculture has largely been held responsible for causing mangrove deforestation, particularly in countries like Thailand and the Philippines.”
-Daniel Richards, study co-author
According to Richards, a study of eight countries around the world between the 1970s and early 2000s found that 54% of deforested mangroves were replaced with aquaculture ponds used for fish or shrimp production.
“Our study found that aquaculture was still important but we were surprised that in Southeast Asia between 2000 and 2012, just 30% of deforested mangroves were replaced with aquaculture.
“The impact of other drivers, like rice and oil palm agriculture, was greater than we expected.
“Almost 25,000 hectares (61,776 acres) of Myanmar’s mangroves were converted to rice paddy between 2000 and 2012.”
According to Richards, previous studies didn’t have an idea of deforestation’s scale.
“Sixteen percent of all deforested mangroves in Southeast Asia were replaced with oil palm plantations during our study period.
“We usually think of oil palm as an issue which affects tropical forests on land but our study shows that demand for oil palm is also driving deforestation in coastal mangrove forests.”
Richards and colleague Daniel Friess used Google Earth to monitor how land was used once mangrove forests were felled.
“We viewed [over] 3,000 deforested mangrove patches, and recorded the land-use that they were replaced with.
“This study also builds on some great existing data sets that were provided by scientists at the University of Maryland and the US Geological Survey.”
Richards warned that mangrove forests in the region were “very threatened.”
“Our study focused on quite a recent period of time but mangroves in Southeast Asia have experienced widespread deforestation for decades.
“Previous research suggests that around 90% of Singapore’s original mangrove forests have been lost.”
The region is home to about a third of the world’s mangroves.
According to the researchers, mangroves were important to people because they provide fish, crabs, wood and charcoal, along with protecting coastlines from erosion. Mangrove forests also store high densities of carbon so they have a role in regulating carbon in the atmosphere.
“It is encouraging that our study found low rates of mangrove deforestation in Vietnam, the Philippines, and Brunei, and this is partly due to stronger protection of mangroves in these counties.
“There are initiatives to restore mangroves in some countries: the Mangrove Action Project in Thailand, and Blue Forests in Indonesia, are working with governments and local communities to protect and restore mangrove forests.
“Indonesia has more mangrove forests than any country in the world, and the mangroves in the more remote parts of the country, such as Indonesian Papua, are almost intact.
“However, these mangroves may be at risk of deforestation [as a result of] recent plans to grant concessions and develop the agriculture industry in this region.
“If we want to protect Indonesia’s remaining mangroves then we need to act quickly.”