The main significant stages of development of vegetation, climate and soils, as well as other palaeogeographical conditions during the Late Glacial and Holocene have been distinguished and are discussed in the paper. The data used in this work have been obtained from investigations of pollen and diatoms in lake and bog sediments, including those of the old Baltic Sea stages in the western part of Lithuania. Six types of pollen diagrams are distinguished for the Late Glacial and Holocene in Lithuania, and the net-like method suggested earlier by the author (Кабайлене, 1969) is used to obtain a reconstruction of the different stages of forest history.
Three stages of natural environmental changes have been distinguished in the Late Glacial and five stages have been singled out in the Holocene. The cold and dry Pre-Alleröd (11900–14000 BP) climate favoured a tundra and forest–tundra vegetation. Considerable warming took place in this area in the Alleröd (10900–11900 BP), with birch and pine becoming dominant. The cooling of the climate during the Younger Dryas gave rise to a forest–tundra vegetation. During the Preboreal and the first half of the Boreal (8100–10000 BP) the climate was warm and dry and the forests were dominated by birch and pine. The Late Boreal, Early and Late Atlantic and Early Subboreal (23700–8100 BP) were the warmest and most humid Holocene stage, so that broad-leaved forests and alder flourished; during the Early Subboreal spruce increased. The amounts of broad-leaved trees and spruce decreased and of herbs increased during the Late Subboreal (2500–3700 BP), birch and pine spread, suggesting a moderately warm, dry climate. The Early Subatlantic (1000–2500 BP) were marked by a spread of dence alder and spruce forests, indicating greater humidity. In the Late Subatlantic (the last 1000 years) climate became cool, pine and birch prevailed among trees, the landscapes were more open.

Keywords: environment, vegetation, climate, soils, lakes, peatbogs, pollen, diatoms, Lithuania