|
Résumé :
|
At all scales (delta-wide to individual fields) the acid sulphate soils of the Mekong delta show high spatial variability and closely intertwined soil types. Focusing on the field level in the Plain of Reeds, clear correlations are observed between soil physical and chemical characteristics, natural vegetation, groundwater table and microelevation. On 'high' locations (higher than 85 cm above mean sea level), Typic Sulfaquepts are covered with Ischaemum spp. (grass). Highly organic and hydromorphic Hydraquentic Sulfaquepts are found in 'low' locations (lower than 75 cm above mean sea level), where Eleocharis spp. (reeds) are dominant. In between, soils and vegetation present intermediate characteristics. These correlations, the high spatial variability and the soil patterns are explained by soil genesis. Because of longer and stronger evaporation on high locations as compared with low locations, small differences in elevation can lead to: important differences in water table level and therefore redox condition. Over long periods, these differences greatly influence soil development and thus, soil types.
|
