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

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Misiak, WM 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
Authors/Creators:Misiak, WM
Keywords: Mountain plants, Mountain ecology, Ecological disturbances, Vegetation dynamics, Plant communities
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:

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

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