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The vegetation ecology of Tasmanian dry closed-forest

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Pollard, T (2006) The vegetation ecology of Tasmanian dry closed-forest. PhD thesis, University of Tasmania.

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Abstract

The subject of this study is a poorly known closed-forest community that occurs as
small, disjunct stands in eastern Tasmania. This community has affinities with dry
rainforest, a formation that occurs extensively in mainland Australia. There is
ongoing debate as to what constitutes Australian rainforest, with most definitions
based on the regeneration requirements of the constituent species. A species must
be capable of self-replacement in the absence of exogenous disturbance to qualify
as a rainforest species. The present study aims to answer the questions:
1. Where does dry closed-forest occur in Tasmania and what environmental
factors influence this distribution?
2. How does the floristic composition of this community vary across its range?
3. What are the modes ofregeneration of the major tree species of this
community and why is Eucalyptus absent?
4. What are the conservation management and reservation requirements of the
community?
Additionally, an overarching aim concerns whether the study community can be
considered rainforest.
To achieve these aims the study: documents the geographic variation of dry closedforest
stands and test the hypothesis that distributional characteristics are related to
fire-avoidance by mapping the location and characteristics of stands and measuring
variables of the local stand environment; documents the floristic variation of dry
closed-forest in relation to environmental variables by conducting a survey of the
vascular plant species composition and stand environment; determines if this
community requires exogenous disturbance for perpetuation, by studying the spatial
arrangement and regeneration-characteristics of major canopy species within
stands; and investigates why Eucalyptus is absent from this community by
conducting experiments of the germination and growth of Eucalyptus and some
comparative dry closed-forest species in a number of soil treatments.
One hundred and eighty three stands were mapped. Stands occupied a number of
different topographic and edaphic situations that afford protection from fire. Six
floristic sub-communities were differentiated, and a number of environmental
variables shown to significantly influence this variation. Floristic similarities were
shown to exist between this community and other Australian rainforest and wetforest
communities. Stands not recently disturbed proved to be dominated by selfreplacing
species, while early-successional stands consisted mainly of species
requiring exogenous disturbance for regeneration. There was no significant
segregation of individuals either within or between species, however seedlings of
bird-dispersed species were clustered around large trees. The germination
experiments indicated that limitations on Eucalyptus establishment are related to
soil properties (particularly damping-off fungi) and competition with dry closedforest
species.
Tasmanian dry closed-forest appears to be a community that has some affinity with
rainforest in terms of distribution, floristic composition, structural attributes and
regeneration strategy. However, the identification of a number of successional
stages of this vegetation type, that require fire for the establishment of a number of
key species, brings into question the status of this vegetation as rainforest. This
only highlights the challenges present in attempting to define Australian rainforest
vegetation.

Item Type: Thesis (PhD)
Keywords: Forest conservation, Forests and forestry, Forest ecology
Copyright Holders: The Author
Copyright Information:

Copyright 2006 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, 2006. Includes bibliographical references

Date Deposited: 03 Feb 2015 03:12
Last Modified: 19 Mar 2017 22:11
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