No abstract

Sedimentary, palynologic, and 14C analysis of 480 cm of freshwater marl and swamp-peat deposits, formed under the influence of fluctuating artesian springs, provides a paleoenvironmental and paleoclimatic record of approximately 65,000 yr for northwestern Tasmania.The Holocene (Pollen Zone 1, 11,000-0 yr B.P.) climate was warm and moist, and forest vegetation was dominant throughout the area. During the later part of the last glacial stage (Pollen Zone 2, 35,000–11,000 yr B.P.) the climate was generally drier, and grassy open environments were widespread. The driest part of this period occurred between 25,000 to 11,000 yr B.P., when temperatures in western Tasmania were markedly reduced during the last major phase of glaciation. Prior to 35,000 yr B.P. (Pollen Zones 3–9) a long “interstadial complex” dating to the middle of the last glacial stage is recognized. During this period the climate was generally moist, and forest and scrub communities were more important than during the later part of the last glacial stage, except during Pollen Zone 5 when high Gramineae plus Compositae values suggest drier conditions. High Gramineae and Compositae values also occur in Pollen Zone 10 at the base of the diagram. They suggest that a phase of drier and cooler climatic conditions occurred during the early part of the last glacial stage.

summary Pollen and plant macrofossils from Langdon liner give an interglacial floral record for western Tasmania. The location of the site between the ice limits of the Last or Margaret Glaciation and the Penultimate or Henty Glaciation indicate that it cannot be younger than the Last Interglacial. The sequence of vegetation changes shows the succession Casuarina Phyllocladus‐Nothofagus with Casuarina as pioneer and Nothofagus as representing Maximum wet forest development. After the maximum the presence of Phyllocladus‐Nothofagus‐Eucalyptus‐Microstrobos suggests deterioration to subalpine woodland/shrubland, and Compositae, Gramineae‐Microstrobos to alpine shrubland and herbland. The sequence represents most of a glacial‐interglacial‐glacial cycle Of environmental changes that occurred before 43 000 14C yr B.P. Very high Casuarina values occur in the early part at the interglacial sequence which contrasts with the Holocene where Eucalyptus is more important than Casuarina. Otherwise the sequence of Phyllocladus, Nothofagus, Eucryphia‐Anodopetalum is the same as for Holocene forest development. The interglaeial ‘optimum’ is marked by the occurrence of Pomaderris apetala type and Dicksonia antarctica. There is some similarity with the Casuarina curves in the Lake George interglacials before the Last Interglacial. But, on the whole, there is more similarity with interglacial rainforest development in western South Island, New Zealand Only one cycle of vegetation change is recognized at Langdon River which is unlike New Zealand and central Chilean records from 40‐42° S which in different ways record a mid Last Interglacial climatic deterioration.

Excavation of peat and clay filling a sink hole has provided a relatively long late glacial to Holocene pollen/vegetation record for the King Valley. The record shows a change from alpine herbland, Microstrobos scrub and heath at 13 ka BP to Eucalyptus subalpine woodland. Phyllocladus-Nothofagus rainforest succeeded after 12.5 ka BP but degenerated to scrub rainforest after 11 ka BP, when Lagarostrobos franklinii expanded. The sequence of local changes occurred while the sink-hole lake was being rapidly infilled and converted to topogenous peat around 12 ka BP.Examination of the timing of changes in vegetation associations in other pollen profiles from different altitudes in western Tasmania indicates that many of the changes are non-synchronous and cannot be related directly to climatic events. They probably reflect the effects of both biological and local environmental factors. The major regional climatic change from alpine to temperate conditions on the lowlands occurred ca. 13 ka BP. Demonstration of non-synchronous changes in the late glacial to early Holocene pollenhegetation associations at several sites contrasts with the view of Markgraf et a/., who infer synchronous changes related to climate. There are no indications in the pollenhegetation sequence of either Aller~d or Younger Dryas events in western Tasmania.Journal of Quaternary Sclence

Pollen analysis of 4 m of peat, swamp-soil and lake sediments dated from 0 to > 43800 years b.p. indicates the occurrence of three major pollen assemblage zones. During Zone 1 (11000-0 years b.p.) the area had temperate rainforest and the climate was warm, moist and interglacial. During Zone 2 ( ?25000-l 1000 years b.p.), correlated approximately with the last period of glaciation, the vegetation was mainly grassland and the climate was considerably colder than present. In late glacial times (14000-11000 years b.p.) pollen of shrub and tree taxa increased, especially during the later part of the period as the climate became warmer and moister. During Zone 3 (more than 4 3 0 0 0 -?25000 years b.p.) the vegetation was predominantly sub-alpine and alpine. This vegetation represents an interstadial assemblage for a lowland site. The climate was cool and moist. The results are compared with sites of similar age in Tasmania, and with sites from temperate forest environments in Chile and New Zealand.