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The impacts of edge effects and other disturbances on Tasmanian coastal heathlands

Loofs-Samorzewski, M 2003 , 'The impacts of edge effects and other disturbances on Tasmanian coastal heathlands', PhD thesis, University of Tasmania.

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Widespread clearing of Tasmanian heathland for pasture and crops has resulted in small
remnants within the agricultural landscape. The conventional wisdom has been that such
small remnants are susceptible to adverse edge effects, particularly those related to
nutrient accession, and thus are not worth conserving. Previous research into the addition of
nutrients in heathlands has involved large amounts of fertiliser. In this thesis realistic
experimental manipulation in the field and widespread observation of boundaries are used
to determine whether there could be a future for small heath remnants.
The effects of irrigating a coastal heathy woodland with sewage water were monitored.
The addition of small amounts of nutrients in the wastewater caused a small increase in
live plant cover but no major plant death or changes in species composition. In a
manipulative field experiment, small amounts of fertilisers were added to simulate
nutrient drift from pasture topdressing, and were combined with fire and weed seed
treatments. There were no effects on cover, species richness and species composition. In a
second manipulative field experiment, fire-fighting foam was applied in combination
with burning. Foam effects included increases and decreases in canopy growth of different
species, a reduction in species richness, reduced flowering and leaf damage. In all three
experiments, exotic species either did not invade over the period of the study or, when
weed seeds were sown, failed to establish. In a survey, the observations of heath—pasture
boundaries showed that different management regimes affected the condition of coastal
heath remnants. The major disturbance that encouraged weed invasion in heathlands was
an increase in soil fertility. Stock grazing, native herbivore grazing and physical
disturbance also adversely affected heath condition. However, edge effects in the form of
increased nutrients and the presence of exotic species did not penetrate more than a few
metres into heathland. In summary, with careful management, small heathland remnants
can be quite resistant to weed invasion and are worth conserving.

Item Type: Thesis - PhD
Authors/Creators:Loofs-Samorzewski, M
Keywords: Heathland ecology, Coastal zone management
Copyright Holders: The Author
Copyright Information:

Copyright 2003 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
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Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2003. Includes bibliographical references

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