Late Quaternary Vegetational History of Southeastern Labrador

Abstract

Pollen percentage and influx diagrams for three lake-sediment cores from southeastern Labrador are subdivided into three regional pollen assemblage zones: (I) Betula-SalixCyperaceae zone, 10,500 to 9000 14C yr BP; (II) Alnus-Abies-Picea zone, 9000 to 5000 BP; (III) Picea zone, 5000 BP to present. Pollen influx was low in zone I, rose in zone II, and then abruptly increased in the upper part of zone II when tree pollen was first deposited in significant amounts. Influx reached a maximum about 4000 yr ago and declined substantially after 2500 BP. An early phase of tundra was succeeded 9000 yr ago by Betula-Alnus shrub-tundra as the climate warmed. Trees then colonized the shrub-tund a at 6000 BP arriving late relative to sites farther south and west. The initial forest community is interpreted as a park-tundra of Picea glauca with abundant Abies balsamea and probably with some Betula papyrifera. After a period of about 700 yr, Abies declined in favor of Picea mariana as soil conditions began to deteriorate. The formation of peat was probably accelerated at this time. The pollen record from a site on the south coast shows that the coastal region was never forested. The pollen influx record shows distinct similarities to that of the inland sites, suggesting that climate was most temperate bout 4000 yr ago and that a deterioration took place about 2500 BP.