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Keywords:

  • ENSO;
  • fire;
  • humification;
  • precipitation;
  • testate amoebae

Abstract

A Holocene record of pollen, macrofossils, testate amoebae and peat humification is presented from a small montane bog. Sediment accumulation began before 9000 yr BP, but peat growth not until ca. 7000 BP. From 12 000 to 7000 yr BP, a shrub–grassland dominated under a dry climate, with increasing conifer forest and tall scrub from ca. 9600 yr BP. At 7000 yr BP a dense montane–subalpine low conifer forest established under a moist, cool climatic regime. Between 7000 and 700 yr BP the bog surface was shrubby, tending to be dry but with highly variable surface wetness. The catchment was affected by major fire at least four times between 4000 and 1000 yr BP. Both fire and bog surface wetness may have been linked to ENSO-caused variations in rainfall. Cooler, cloudier winters and disturbance by fire promoted the expansion of the broadleaf tree Nothofagus menziesii between 4000 yr BP and 1300 yr BP at the expense of the previous conifer forest–scrub vegetation. Polynesian fires (ca. 700 yr BP) reduced the vegetation to tussock grassland and bracken. Deforestation did not markedly affect the hydrology of the site. European pastoralism since ad 1860 has increased run-off and rising water tables in the bog have led to a Sphagnum-dominated cover. Copyright © 1999 John Wiley & Sons, Ltd.