Etude historique de la végétation durant le tardi-glaciaire et le post-glaciaire en Peräpohjola (Laponie méridionale en Finlande) par la méthode sporo-pollinique

Abstract

On the basis of pollen‑analytical investigations of sediments from five lakes, an attempt is made to describe and explain the vegetational history of Peräpohjola (Finland), following the withdrawal of the conti­nental ice sheet. Special attention is paid to the regional late‑glacial pollen flora contained in the basal sediments from Laihalampi, which are Flandrian in age (9600 yr.BP). Detailed determinations of the Betula species based on both size and morphological criteria show that the pioneer vegeta­tional phase on those sites which were deglaciated first was mainly treeless. The pioneer vegetation was an association of both heath and steppe elements and was time‑transgressive. The general scheme of the vegetation history is based on the division of the diagrams into Pollen Assemblage Zones after West (1970). It shows only a few regional discrepancies with what is already known for other regions in Finland.