Late Holocene human impact and climate change recorded in a North Swedish peat deposit

Abstract

A peat core from a mire with poor fen lawns and ombrotrophic hummock strings in Northern Sweden was examined (plant macrofossils, pollen/non-pollen microfossils, testate amoebae, colorimetric humification, carbon/nitrogen ratios, bulk densities, loss on ignition) to investigate the effects of climate change and human impact on the plant species composition and peat accumulation of the peat forming vegetation during the last 1700 yr. 14C wiggle-match dating was applied for high-precision dating. The Lappmyran region was dominated by Pinus and Picea forest. Changes in land-use patterns and population density were visible in the pollen record of the regional vegetation. Juniperus and Rumex acetosa-type pollen indicated the presence of grazed land in the area between AD 1500 and 1950. The vegetation at the coring spot gradually became ombrotrophic. The local plant and testate amoebae compositions reflect changes in surface wetness caused by changes in precipitation and the internal dynamics of the bog. A wet interval was observed during the Maunder minimum of solar activity. The presence of Drepanocladus fluitans indicates less ombrotrophic conditions during this period probably caused by the inflow of minerogenic water from upslope owing to increased precipitation. The reconstructed water table shows agreement with precipitation measurements which were available since AD 1860.