Lateglacial and Holocene vegetation history at Nisi Fen and the Boras mountains, northern Greece

Abstract

New pollen data from three contrasting sites in northern Greece allow an analysis of spatial and temporal patterns of vegetation change during the Holocene and Lateglacial in northern Greece. At the principal site, Nisi Fen, six cores from the thickest surficial peat deposits have yielded a detailed, composite, AMS14C-dated pollen record covering the period from 20000 cal. BP almost to the present-day. Cores Kp-4 and Bor-3 were taken from small mires at high elevations in the Boras mountains, a few kilometres to the north of Nisi, in which peat has been accumulating since the mid-Holocene. Our results show that only Pinus expanded significantly during the Lateglacial Interstadial, although small thermophilous tree populations were present in the region. The Younger Dryas chronozone is at best marked by subtle vegetational change in favour of steppe taxa. Tree cover increased rapidly at the beginning of the Holocene, with deciduous woodland probably expanding above its present-day altitudinal limits. There is evidence for drier and/or warmer summers, and mild winters, between c. 10500 and 7500 cal. BP, although the vegetation was not as markedly sclerophyllous as at many sites elsewhere in Greece. The mid-Holocene saw a reorganization of the woodland, with first Abies and then Fagus becoming important at high altitudes, and an increase in the diversity of deciduous woodland at medium elevations. The suggestion of human impact in the form of a decline in woodland and the appearance of crops in the pollen record can be found at all altitudes in the later Holocene.