Problematyka paleoekologiczna w kompleksowych badaniach okolic Jeziora Lednickiego

The palaeoecological studies were taken up a few years ago as a component part of the interdisciplinary works planned on a wide scale. There are many subjects of the palaeoecological studies in the Lednica Lake region, and this region is characterized by variety of archeological discoveries which may afford much information on the past nature, particularly on the range and evolution of the human impact. Among other things, the following were included in the thorough aims of the studies: — the reactions of the plant cover in comparison with different types of interference of the human activity in the past, — regenerative ability of forest and water ecosystems after destructions, — the change in the trophic gradient; the role of the activity of man and the climate in these: changes, — the palaeohydrology of this region, — the palaeopaedology with reference to the changes of the plant cover. To obtain the above mentioned aims numerous methods recommended for palaeoecological and palaeohydrological studies have been used. The subject of the particular interest is the history of the vegetation investigated by different methods, especially the pollen analysis, fossil diatans,. radiocarbon datings, dendrochronology, stable isotopes. Fig. 1 shows the present state of the palaeoecological studies in the described region. It depicts the distribution of 3 groups of sites. From the groups of sites under investigation, the following should be mentioned: — the Skrzetuszewskie lake (situated westwards from the west end of the Lednica Lake bay. This site has two pollen diagrams) the littoral and the profundal core: subfossil diatoms, macroscopic Plant kemnaus, radiocarbon datings. This lake belongs to the on primary reference sites of International Geological Correlation Programme, project 158 В “Palaeohydrological changesin the temperate zone in the last 15.000 years” . — The peatbog near Dziekanowice village. The first part of the palaeobotanic studies of the Late — Glacial flora (with Salix herbacea, Dryas octopetala, Betula nana and many other plants litt 1986 - 1987) and the pollen analysis of the sediments from the shore zone of Lednica island has been finished. Besides, the early-mediaeval flora of vascular plants is being examined now, and the subaquatic culture layers near the wooden bridge relicts (s.c. Poznan bridge) are being -worked out.