This dataset contains site requirements/tolerance limits (or "reference values") for 28 vegetation types found in Flanders. It gives the lower and upper limits or the classes within which these vegetation types can occur, for 7 site factors that determine potential vegetation development. These reference values can be used to determine the potential distribution of the different vegetation types with the ecohydrological model NICHE Flanders ( Callebaut et al. 2007 , in Dutch). See the Technical info (available in English and Dutch) for more information. ; This dataset contains site requirements/tolerance limits (or "reference values") for 28 vegetation types found in Flanders. It gives the lower and upper limits or the classes within which these vegetation types can occur, for 7 site factors that determine potential vegetation development: soil type, more specifically the NICHE ecological soil type (8 classes) nutrient level (5 classes) acidity level (3 classes) mean lowest groundwater level (lower limit-upper limit) mean highest groundwater level (lower limit-upper limit) type of management (4 classes) flooding regime (3 classes) These reference values can be used to determine the potential distribution of the different vegetation types with the ecohydrological model NICHE Flanders ( Callebaut et al. 2007 , in Dutch). Origin of the reference values The reference values are based on extensive field sampling across Flanders of both vegetation and (a)biotic environmental variables that are (in)directly linked to each of the input layers of the ecohydrological model NICHE Vlaanderen (see Callebaut et al. 2007). Site factors 1.NICHE ecological soil types In NICHE Flanders ecological soil types are defined, mainly based on grain size and organic matter content, which determine soil moisture conditions, acidity and trophic level.The following ecological soil types are discriminated: K1 alluvial clay soils, poor in organic matter KV alluvial clay soils, rich in organic matter, peaty clay, clay on peat V peat Z1 ...