Substantial mangrove deforestation in Myanmar

NUS scientists found that more than 60% of the mangrove cover in Myanmar had been converted to agricultural and other purposes over a period of 20 years (1996 – 2016).

Mangroves account for only 0.7% of the Earth’s tropical forest area but are critically important coastal forests that provide a wealth of ecosystem services, including biodiversity conservation, support of local livelihoods, and protection from threats such as coastal surge associated with storms and tsunamis. Many countries have established legal protection for mangroves, yet their value for sustainable ecosystem services strongly compete with short-term gains from conversion to other forms of land use, in particular agriculture and plantations. Thus, it has been well-known from studies that for the past decade, mangrove deforestation rates are typically higher than inland terrestrial forest deforestation rates.

A research team led by Prof Edward WEBB and researcher Mr Jose Don DE ALBAN from the Department of Biological Sciences, NUS found that deforestation rates in Myanmar, a globally important country for mangrove extent and biodiversity, greatly exceed previous estimates. Satellite image datasets from the United States’ Landsat optical sensor and Japan’s L-band radar sensor were used in their land cover mapping and land change analysis. Using available imagery from three time points (i.e. 1996, 2007 and 2016), the team assessed the extent of mangroves in Myanmar starting from 1996 and followed the changes associated with every 30-metre by 30-metre mangrove image pixel. The team found that over a 20-year period, more than 60% of the land area covered by mangroves in Myanmar had been permanently or temporarily converted to other land cover types including rice, oil palm and rubber plantations, shrubland and urban areas. These competing land cover types are commercially important but incompatible with mangrove persistence. Surprisingly, they found that fish and prawn farms accounted for only a minor amount of mangrove conversion, but this may change in the near future.

Prof Webb said, “The research highlights the tenuous future for mangroves in Myanmar and magnifies arguments for greater protection for a critical coastal ecosystem. This is particularly important as Myanmar strives to become more integrated into the regional and global markets for agriculture and aquaculture products. The fate of mangroves in Myanmar will be tied to the effectiveness of conservation policies while under pressure to convert to more lucrative but environmentally harmful land uses.”

On the left, Google Earth ^TM imagery depicting mangrove conversion into competing land uses along the coastline of Myanmar. “Before” and “After” images correspond to the closest available imagery for the 2007 and 2016 time-points respectively. Locations of these sample points are annotated as “red” boxes on the Bing Maps ^TM (Virtual Earth) basemap on the right, showing mangrove loss to [1] rice paddy in Rakhine, [2] bare ground in Ayeyarwady, [3] rubber and [4] oil palm plantations in Tanintharyi. The study region (shaded white polygons) encompass six out of fifteen sub-national regions of Myanmar (solid white border) where mangroves are found. Inset images are North-aligned to the basemap.

A pristine mangrove forest dominated by Rhizophora mucronata at Lampi Island in Tanintharyi region, Myanmar. [Credit: Maung Maung Than]

Reference

JDT De Alban*; J Jamaludin; DW Wen; MM Than; EL Webb*, “Improved estimates of mangrove cover and change reveal catastrophic deforestation in Myanmar” ENVIRONMENTAL RESEARCH LETTERS Published: 2020.