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The Flood Pulse as the Underlying Driver of Vegetation in the Largest Wetland and Fishery of the Mekong Basin

Abstract

The Tonle Sap is the largest wetland in Southeast Asia and one of the world’s most productive inland fisheries. The Mekong River inundates the Tonle Sap every year, shaping a mosaic of natural and agricultural habitats. Ongoing hydropower development, however, will dampen the flood pulse that maintains the Tonle Sap. This study established the current underlying relationship among hydrology, vegetation, and human use. We found that vegetation is strongly influenced by flood duration; however, this relationship was heavily distorted by fire, grazing, and rice cultivation. The expected flood pulse alteration will result in higher water levels during the dry season, permanently inundating existing forests. The reduction of the maximum flood extent will facilitate agricultural expansion into natural habitats. This study is the most comprehensive field survey of the Tonle Sap to date, and it provides fundamental knowledge needed to understand the underlying processes that maintain this important wetland.

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Acknowledgments

Funding was provided by the University of Canterbury International Student Doctoral Scholarship and a grant by the Critical Ecosystem Partnership Fund entitled “River at Risk: Modeling and monitoring the potential impacts from large-scale disruptions to the hydrological cycles of the Mekong River Basin.” Special thanks also to Conservation International-Cambodia for providing in-country coordination, Cambodia Ministry of Environment for field support, and Mariana Esteves, Phanny Sros, Thanapon Piman, and Taber Hand for field assistance. Comments from peer reviewers were also extremely helpful in improving this paper.

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Correspondence to Thomas A. Cochrane.

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Arias, M.E., Cochrane, T.A., Norton, D. et al. The Flood Pulse as the Underlying Driver of Vegetation in the Largest Wetland and Fishery of the Mekong Basin. AMBIO 42, 864–876 (2013). https://doi.org/10.1007/s13280-013-0424-4

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Keywords

  • Cambodia
  • Ecohydrology
  • Wetlands
  • Tropical floodplain vegetation