Rapidly Accelerating Deforestation in Cambodia’s Mekong River Basin: A Comparative Analysis of Spatial Patterns and Drivers

Abstract

The Mekong River is a globally important river system, known for its unique flood pulse hydrology, ecological productivity, and biodiversity. Flooded forests provide critical terrestrial nutrient inputs and habitat to support aquatic species. However, the Mekong River is under threat from anthropogenic stressors, including deforestation from land cultivation and urbanization, and dam construction that inundates forests and encourages road development. This study investigated spatio-temporal patterns of deforestation in Cambodia and portions of neighboring Laos and Vietnam that form the Srepok–Sesan–Sekong watershed. A random forest model predicted tree cover change over a 25-year period (1993–2017) using the Landsat satellite archive. Then, a statistical predictive deforestation model was developed using annual-resolution predictors such as land-cover change, hydropower development, forest fragmentation, and socio-economic, topo-edaphic and climatic predictors. The results show that almost 19% of primary forest (nearly 24,000 km2) was lost, with more deforestation in floodplain (31%) than upland (18%) areas. Our results corroborate studies showing extremely high rates of deforestation in Cambodia. Given the rapidly accelerating deforestation rates, even in protected areas and community forests, influenced by a growing population and economy and extreme poverty, our study highlights landscape features indicating an increased risk of future deforestation, supporting a spatial framework for future conservation and mitigation efforts.

Changing Land Use and Population Density Are Degrading Water Quality in the Lower Mekong Basin

“…The climate of the Lower Mekong Basin is tropical, with a dry season from December to May and a wet season from June to November. Most forested areas are in Laos and Cambodia, although high rates of deforestation have recently occurred [9]. Lowland areas are dominated by rice cultivation [17].…”

“…In addition to its economic importance, the Mekong River Basin is also a hotspot for biodiversity and is home to critically endangered mega-fish species [6]. Despite its ecological and economic importance, the Mekong Basin is experiencing high rates of environmental degradation from multiple causes such as deforestation, rapid population growth, agricultural development, fish overharvest, and dam development [7][8][9][10].…”

“…Drivers of land use change vary between countries in the lower Mekong Basin, but in the last 30 years deforestation has increased in Cambodia, Laos, Thailand, and Vietnam [11]. Of these countries, Cambodia has the most forested land, but is experiencing particularly high deforestation rates, with 19% of tropical forest, 31% of the floodplain, and 18% of upland forest converted to other uses from 1993 to 2017 [9]. In addition to forest loss, the use of fertilizers for agriculture, and in particular rice production, has increased [12].…”

A Meta-Analysis of Environmental Tradeoffs of Hydropower Dams in the Sekong, Sesan, and Srepok (3S) Rivers of the Lower Mekong Basin

“…At a broader scale, dam building also affects terrestrial systems and society. For example, dam building contributes to deforestation as forests are cleared around reservoirs, roads and other infrastructure are built, settlements form, and forest is converted to agriculture [84]. These changes are coupled with climate warming, which is anticipated to increase drought frequency of intensity in the 3S Basin and LMB [85].…”

“…Hydropower dams are one of many substantial changes anticipated in the 3S Basin and LMB. Other threats include ongoing deforestation, urbanization, and climate change [84,88]. Ignoring the environmental costs of hydropower development in the 3S Basin and LMB is likely to be costly.…”