Pollen sedimentation in relation to the Quaternary vegetation history of the Snowy Mountains of New South Wales

Abstract

Pollen influx into Blue Lake in the alpine area of the Snowy Mountains of southeastern Australia was measured by pollen traps, snow and stream water samples and lake sediment traps. Pollen deposition in a nearby forested area was also investigated. Pollen deposition rates were calculated for a pair of cores from the lake, yielding a record over the last 13000 years, supplementary material from the nearby Twynam Cirque extending the sequence to 20000 years B.P. Possible causes of distortions in the pollen diagrams arising from differential pollen deposition and sediment redeposition are regarded as not significant. Vegetation was absent from the area before 17000 B.P., when snowpatch and feldmark communities appeared. Further amelioration occurred between 13000 and 17000 years B.P., after which conditions appeared to remain the same until 8700 years B.P., when a great increase in total pollen deposition rate was associated with rise of the treeline to its present position, and further development of the alpine vegetation. Forest of moister aspect than the present day prevailed from 7700 to 6500 years B.P., after which relative wetness declined to a minimum at about 3800 years B.P. Slight increase in available moisture has occurred since 1500 years B.P