Open Access Repository

The history of the vegetation and climate in southern Tasmania since the late Pleistocene (ca. 13. 000 - 0 BP

Downloads

Downloads per month over past year

MacPhail, Michael Keith (1975) The history of the vegetation and climate in southern Tasmania since the late Pleistocene (ca. 13. 000 - 0 BP. PhD thesis, University of Tasmania.

[img]
Preview
PDF (Vol 1 parts 1-4)
whole_MacPhailM...pdf | Download (21MB)
Available under University of Tasmania Standard License.

| Preview
[img]
Preview
PDF (Vol 1 parts 5-7)
whole_MacPhailM...pdf | Download (26MB)
Available under University of Tasmania Standard License.

| Preview
[img]
Preview
PDF (Vol 2, excluding published material)
whole_MacPhailM...pdf | Download (2MB)
Available under University of Tasmania Standard License.

| Preview
[img] PDF (Vol 2)
whole_MacPhailM...pdf | Request a copy
Full text restricted
Available under University of Tasmania Standard License.

Abstract

This thesis contains the results and conclusions of the first
research in Tasmania using pollen analysis to elucidate the postglacial
history of the vegetation, hence changes in the climate, of Tasmania since
the late Pleistocene.
In contrast with mainland Australia, latitude, size and insular
nature, topography, climate and vegetation combine to make the State highly
suitable for pollen analysis, but also difficult as regards practical implementation
of the technique. Published surveys of Tasmanian biogeography are
inadequate. Hence. the original data are preceded by reviews of the present-day
Tasmanian climate, physiography and plant ecology and prehistory in
addition to a discussion of the limitations of pollen analysis in palaeoenvironmental
research in the Australian phytogeographic context. The conclusions
from previous geomorphic studies of Tasmanian Pleistocene landforms
have been tested using the fossil pollen data from southern Tasmania.
To enable as objective an interpretation as possible of this
fossil pollen data, the present-day pollen rains across Tasmania were studied
via surface sampling and pollen trapping programmes. Despite vandalism of
most pollen traps, sufficient data were gained to determine (i) the approximate
representivity of phytosociologically important taxa, (ii) seasonal
changes in the composition of the pollen rains, (iii) changes in the composition
of modern pollen spectra with changes in the distance or composition
of source vegetation types, and, (iv) the identification of a regional
pollen rain.
Fossil pollen sequences from Frenchmans Cap, Mt. Field National
Park, Adamsons Peak and Lake Tiberias were found to sensitively record the
postglacial vegetational history of western, central southern, far south-eastern
and eastern Tasmania respectively. The individual plant successions
recorded are ecologically consistent with known directions of change in the
modern vegetation continuum dictated by gradients in temperature, precipitation
and fire-pressure. Despite differences in altitude and geographic
location of the core sites, regional parallelism exists between all pollen
sequences. Geographic patterns in the Tasmanian vegetation and their
relationships in time (based on eleven radiocarbon dates) since the late
Pleistocene are broadly consistent with gradients in the environment at
least sub-parallel to the modern, largely unidirectional, gradients in
climate.
It is concluded that late Pleistocene climates were markedly
colder and probably drier than at present. A progressive reduction
precipitation eastwards across the State may have resulted in 'glacial -
arid' climates in eastern Tasmania. Late Pleistocene vegetation was virtually
herbaceous: grasslands in eastern and central Tasmania, and either
grasslands or sclerophyll heath and sedgelands in western and far southern
Tasmania.
A major rise in temperature (recorded globally) between ca.
12,000 - 10,000 BP, accompanied by rising precipitation totals, resulted
in the expansion of arboreal taxa across Tasmania and upslope onto the
mountains. Precipitation limitations in eastern Tasmania delayed the
development of forests here until after ca. 9500 BP. There is no pollen
evidence for any major shift in climate in southern Tasmania since this
rapid rise in temperature.
During the Holocene, plant communities on the mountains studied
have developed from alpine sedgeland / fell-field, through alpine coniferous
and sclerophyll heath or scrub, to subalpine forests dominated successively
by Eucalyptus, Phyllociadus; Nothofagus cunninghamii and again Eucalyptus .
(mixed forests of rainforest and sclerophyll spp. in western and far
southern Tasmania). Eucalyptus has remained the forest dominant in eastern
Tasmania and eastern regions of the Central Plateau. Both the individual
vegetation histories and regional differences in vegetation imply, with
varying degrees of probability, due to the possibility - chat the changes
observed were due to Aboriginal fires, initially rapfd increases in precipitation
and temperature towards, and a slower reversal from, an 'optimum'
in which •climates were nor-! equable or slightly wetter and warmer than
modern climatic averages, between ca. 8000 - 5000 BP. There is no definite
evidence that the climatic timberline in Tasmania has been at altitudes
above its present-day level.
Structural changes in the Tasmanian vegetation since the late
Pleistocene closely parallel those recorded at latitudes equivalent to
Tasmania in New Zealand and Chile. This suggests that postglacial events
in Tasmanian vegetation reflect changes in environment common to the middle
latitudes of the southern hemisphere as a whole, rather than merely the
parochial effects of the Tasmania Aboriginals.

Item Type: Thesis (PhD)
Keywords: Pollen, Fossil, Vegetation and climate
Copyright Holders: The Author
Copyright Information:

Copyright 1975 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Available for use in the Library and copying in accordance with the Copyright Act 1968, as amended. Thesis (Ph.D.)--University of Tasmania, 1976. Includes bibliography

Date Deposited: 19 Dec 2014 02:22
Last Modified: 11 Mar 2016 05:56
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP