Changes in the aquatic flora along a stretch of the river Ume�lven, N. Sweden, following hydro-electric exploitation

Abstract

An attempt to use floristic analysis to monitor the vegetational changes along a stretch of the river Umealven, N. Sweden, following hydro-electric works is described. The aquatic flora list includes 45 phanerogamic taxa, of which 39 were present in 1977. Changes in such ecological factors as e.g. frost action, silting, water flow and water-level amplitude were noted. So far, these have only affected the abundance and vertical distributions of some species; few have disappeared or immigrated. The method used is consifered to be insufficiently precise for establishing whether or not vegetational changes have occurred in such habitats.