LAKE VITALIEVSKOYE (VALAAM ISLAND) ISOLATION PROCESS AND VEGETATION DYNAMICS DUE TO CHANGES IN THE LEVEL OF THE LAKE LADOGA DURING THE LATE HOLOCENE<a href="#FN1">¹</a>

Abstract

The macrophyte pollen is a valuable source of information about lake level changes. Continuing our previous studies on the use of the macrophytes pollen analysis in the paleolimnology we studied the Lake Vitalievskoye sediments sequence of on the Valaam Island (the northern part of Lake Ladoga). To confirm the results of pollen analysis we conducted lithological and diatom analyzes. The macrophytes distribution of the island lakes at the present time has been established with the help of geobotanical and pollen analyzes of the lacustrine surface sediments. As a result, a comprehensive study made it possible to establish the stages of the Lake Vitalievskoye development during the Late Holocene: The Lake Ladoga Bay stage with a slight overgrowth of aquatic vegetation; the lake isolation stage of the from Lake Ladoga, when macrophytes disappeared from the lake, and the lake independent development stage, when their maximum distribution occurred and later began to decline as a result of the human impact. According to our research of the Valaam Island lakes we have received new data about the modern distribution of macrophytes in the island lakes, their dynamics in the Late Holocene. We also conducted a methodological study establishing the macrophytes pollen role in studying the small island lakes history and the Lake Ladoga level.