The diatom assemblages in the Holocene sediments of lake Prestvannet have been investigated. The diatom taxa are grouped according to their ecological requirements to give information on habitat, salinity, pH and current conditions. The diatom assemblages reflect a development from a nutrient-rich recently deglaciated environment to a lake with more moderate nutrients and more shallow conditions. At present the lake has changed back to more nutrient-rich conditions, probably as a result of agriculture.
The planktic flora of the uppermost sediments pro ba bly is a result of the damming of the lake.