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