Delineation of water level regime for major vegetation types in a large tropical floodplain of Tonle Sap Lake, Cambodia

Author(s): Sophanna Ly
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Institution or organization of origin: Tokyo Institute of Technology
Country: Japan


In the floodplain, water level regime affects vegetation (i.e., the distribution and structure). However, there is still a lack of understanding of the relation between the dynamic water level fluctuations and the vegetation. Therefore, we scrutinized the relation between the water level regime and major vegetation types in a large tropical floodplain of Tonle Sap Lake, Cambodia. We employed a 2-D local inertial equation model to spatially elucidate the inundation pattern in the floodplain during 1998−2003. On hydrological year basis, ecologically relevant indices of water level regime (e.g., annual inundation duration and mean water depth) were quantified using the ESRI 2020 land cover map (10-m resolution). The duration of inundation of the flooded forests ranged from 259 days to 302 days (annual mean water depth:1.2m–2.9m), whereas that of shrubs was from 232 days to 273 days (annual mean water depth:0.9m–2.3m). Grasslands and other flooded vegetation were characterized by the duration of inundation of 256–294 days (annual mean water depth:1.3m–2.9m) and 276–317 days (annual mean water depth:1.5m–3.3m), respectively. The spatial distribution of the flooded vegetation implied their close relation to water level regime. The distribution of flooded forests was found close to the permanent lake or waterbodies, while shrubs were found in shallower habitat condition than that for flooded forests. The outcome of this study is useful for understanding the ecological significance of the water regime in this tropical floodplain and the potential effects of the shifting water regime on their distribution and ecosystem service.

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