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Limits to plant regeneration in alpine vegetation on Tasmania's central plateau

Misiak, Wieslawa Magdalena (2007) Limits to plant regeneration in alpine vegetation on Tasmania's central plateau. PhD thesis, University of Tasmania.

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Abstract

The long history of disturbance by human activities on Tasmania's Central Plateau has
resulted in some of the most eroded alpine and subalpine country in Australia. Although
the rate of vegetation and soil loss has declined following the introduction of
myxomatosis, prohibition of burning, and the exclusion of stock grazing within the
Tasmanian Wilderness World Heritage Area, recovery has been relatively slow, and
erosion continues to occur. This study examined some of the current biotic and abiotic
parameters affecting plant regeneration in alpine vegetation in the Central Plateau region.
Seed traps were used to assess the availability of seed for regeneration in different
microhabitats. There were significant seasonal and locality differences in seed density
and species richness. A total of 14 to 24 seed taxa per site were trapped over a 14 month period. Average seed densities per month ranged from 5 to 3,090 seeds m-2• In general,
bare microhabitats captured similar numbers of seeds and taxa to those trapped in
existing vegetation clumps, at the edges of prostrate Grevillea australis, and directly
underneath this shrub. Germination trials of a variety of species showed high
germinability under wide temperature regimes, indicating the potential for recruitment
throughout much of the year. In addition, pitfall trapping found little evidence of
invertebrate taxa associated with post dispersal seed harvesting in the area, but potential
predation by small mammals and birds cannot be excluded.
Some aspects of microclimate in eroded bare patches and under G. australis were also
recorded. This native shrub species appears to play an important role in ameliorating the
microenvironment for seedling establishment due to its prostrate habit, which limits
levels of excessive solar radiation, velocity of desiccating wind gusts, and the extent of
frost heave activity. Consequently, numbers of seedlings were significantly higher under
Grevillea shrubs than in open patches throughout the year, despite seed arrival being
similar. The frequency of freeze-thaw cycles, minimum soil surface temperature and
relative humidity however, were not detectably different between. open and Grevillea microhabitats, while jute matting and Orites acicularis slash were effective in increasing
minimum soil surface temperatures and relative humidity, and reducing freeze-thaw and
frost heave activity compared to bare areas. Unexpected microclimatic readings could be
attributed to the highly heterogeneous nature of the microhabitats.
This baseline data will improve our understanding of the processes and requirements for
regeneration in highland areas and contribute to effective conservation and ecosystem
management.

Item Type: Thesis (PhD)
Keywords: Mountain plants, Mountain ecology, Ecological disturbances, Vegetation dynamics, Plant communities
Copyright Holders: The Author
Copyright Information:

Copyright 2007 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 library use only but NOT for copying until 30 November 2009. After that date, available for use in the Library and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2007. Includes bibliographical references. Ch. 1. Introduction -- Ch. 2. Microclimate -- Ch. 3. Seedling survivorship -- Ch. 4. Seed rain -- Ch. 5. Fate of seeds - post-dispersal predation -- Ch. 6. Fate of seeds - germination -- Ch. 7. General discussion and management implications

Date Deposited: 03 Feb 2015 03:04
Last Modified: 14 Nov 2017 03:57
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