Changes in macrophytic flora and planktonic organisms in Lake Ostrowite, Poland, as a response to climatic and trophic fluctuations

Abstract

This article presents some selected results of palaeoecological analysis based on subfossil pollen and Cladocera in a core of deep-water sediments. It was drilled in the SW part of Lake Ostrowite in National Park Bory Tucholskie, Poland. The core contains fine-detritus gyttja with no calcium carbonate. Nine local pollen assemblage zones show the stages of vegetation succession around the lake from the Younger Dryas through the Holocene up to the present time. Local pollen assemblage zones and seven phases in the development of Cladocera permit ecological reconstruction and description of local changes in the lake itself. Changes of trophic status are based on the quality and quantity of Cladocera species and the curve of Pediastrum. Human activity around Ostrowite is discussed in relation to the changes in regional plant cover and the trophic state of the lake.