Preview

PDF (Whole thesis) whole_WhinamJen...pdf | Download (6MB) Available under University of Tasmania Standard License. | Preview

Abstract

The ecology of Sphagnum peatlands in the southern hemisphere has been poorly
understood. Comparisons with northern hemisphere literature suggest that Tasmanian
Sphagnum peatlands are limited in their morphology and geomorphic expression,
possibly due to relatively low effective precipitation. While Sphagnum bogs tend to
occupy nutrient poor situations in the northern hemisphere, in Tasmania they do not
occur on the poorest substrates, despite climatic suitability.
To provide data on spatial variability of Tasmanian Sphagnum mires, a survey of 137
sites across Tasmania was carried out. Plant species composition and cover, peat
depths and height of hummocks were recorded. Climatic data were generated by using
the computing package BIOCLIM. Peats from a subset of samples were analysed for
their nutrient composition. Eight ecologically distinct groups spanning an almost
continuous gradient from high to low altitude sites were recognised. Floristic variation
between sites along this gradient can largely be explained by location along secondary
gradients of nutrient availability and disturbance (fire).
In a glasshouse experiment, the dry matter biomass of S. cristatum showed no
significant relative effects when subjected to drought, fertiliser or shade treatments,
either singularly or interactively. Shade resulted in a reduced biomass of Sphagnumassociates,
suggesting that shade affects the competitive ability of other species.
Monitoring of exclosure and control plots provided data which suggest that grazing
may result in the maintenance of conditions suitable for Sphagnum by altering interspecific
competition. The effects of grazing appear to be more pronounced at lower
altitude, high productivity sites than at higher altitudes. There was no evidence to
suggest that marsupials graze Sphagnum moss.
Monitoring of a site subjected to a low intensity burn provided some short-term data on
this disturbance event. Initial effects varied according to the vegetation present, which
influenced the local severity of the fire. The most significant change appears to be a
drying out of the peatland, which has resulted in a decline of Sphagnum.
Macrofossils from peat cores have enabled a possible model of Sphagnum peatland
succession in Tasmania to be developed. Succession appears to be multi-directional,
with micro-successional changes occurring across mires in response to extremely local
events. While the major successional pathway suggested by these cores is from
Sphagnum/Restiad to Sphagnum mires, progressfon to sites dominated by herbs and
shrubs is possible.

Item Type:	Thesis - PhD
Authors/Creators:	Whinam, Jennie
Keywords:	Peat mosses, Peatland ecology, Peat-bogs
Copyright Holders:	The Author
Copyright Information:	Copyright 1992 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:	Thesis (Ph.D.)--University of Tasmania, 1992. Includes bibliographical references (leaves 127-137)
Item Statistics:	View statistics for this item

Actions (login required)

Item Control Page