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Dan Hammarlund

Dan Hammarlund

Professor

Dan Hammarlund

Boreal forest dynamics in north-eastern Sweden during the last 10,000 years based on pollen analysis

Författare

  • Lena Barnekow
  • Petra Bragée
  • Dan Hammarlund
  • Natalie St. Amour

Summary, in English

A pollen record obtained from a 2.2-m sediment succession deposited in a small lake in the province of Vasterbotten, north-eastern Sweden, reveals the presence of continuous forest cover since 8,500 calendar years before present (cal B.P.). Forest with abundant Pinus (pine) and Betula (birch) initially colonized the area, followed by a dominance of deciduous trees, primarily Betula, from ca. 8,000 to ca. 3,200 cal B.P. Pollen accumulation rates of Quercus (oak), Ulmus (elm) and Tilia (linden) suggest the possible local presence of these thermophilous tree species during this period. The climate gradually became colder and moister around 3,500 cal B.P. and an increased abundance of Sphagnum spores indicates paludification. Picea (spruce) became established around 3,200 cal B.P. and less than 500 years later this was the dominant tree species around the lake. The fire frequency as inferred from charcoal particles exhibits a general increase from ca. 3,000 cal B.P. with subsequent charcoal accumulation maxima at around 2,800 cal B.P., 1,700 cal B.P. and in recent time. The human influence on vegetation was significant during the last 200-300 years. Soil erosion increased substantially and fern spores amount to ca. 55% of the total pollen assemblage in the uppermost samples. These results suggest an extensive anthropogenic impact on the local forest ecosystem, with abundant logging, burning and ditching in the vicinity of the lake. Independent evidence of sub-recent human-induced environmental change is provided by historical accounts. Complementary information on catchment soil development and aquatic nutrient status was provided by records of magnetic susceptibility and elemental carbon, and nitrogen contents obtained from the same sediment core.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2008

Språk

Engelska

Sidor

687-700

Publikation/Tidskrift/Serie

Vegetation History and Archaeobotany

Volym

17

Issue

6

Dokumenttyp

Artikel i tidskrift

Förlag

Springer

Ämne

  • Geology

Nyckelord

  • Fire frequency
  • Human impact
  • PAR
  • C/N ratio
  • Spruce immigration

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0939-6314