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The ecology and habitat requirements of saproxylic beetles native to Tasmanian wet eucalypt forests : potential impacts of commercial forestry practices

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Yee, Marie (2005) The ecology and habitat requirements of saproxylic beetles native to Tasmanian wet eucalypt forests : potential impacts of commercial forestry practices. PhD thesis, University of Tasmania.

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Abstract

Large diameter Eucalyptus obliqua decaying logs are characteristic features of wet
eucalypt forests in Tasmania. In production coupes, however, rotation lengths of around
80 years will eventually lead to their elimination. This thesis investigates the role of
these features as habitat for saproxylic beetles, and thus whether their retention is
warranted to maintain biodiversity. Large diameter (> 1 OOcm) logs derived from
commercially over-mature trees were compared with small diameter (30-60cm) logs
derived from trees of an age approaching commercial maturity, in two forest types:
mature, unlogged forest; and 20-30 year logged forest that had regenerated after
clearfelling.
Two field studies were conducted, in which a highly species rich fauna of 360
saproxylic beetle species (representing 54 families) are first recorded.
The first, destructive sampling study investigated whether small diameter logs follow
similar decomposition processes to large diameter logs, and so support similar rot types
and beetle assemblages. Eleven rot types were differentiated, each associated with a
particular region within the log. Small diameter logs had a relatively high incidence of
white rot towards their outer edges, probably originating from fungal colonisation after
treefall. Large diameter logs had a higher incidence of brown rot towards their cores,
probably originating from internal decay already present in older, living eucalypt trees
prior to treefall. Some of the beetle species characteristic of this brown rot are possibly
poor dispersers and may be of particular conservation concern in production forests.
The second, log emergence trapping study examined the extent to which beetle
assemblages differ between small and large diameter logs, and whether they respond in
the same way to forest successional processes induced by stand level disturbance.
Distinct suites of species were associated with large diameter logs irrespective of forest
type, yet there were no apparent small log specialists. Assemblages differed
significantly between the mature and logging regenerated forests; there was also
significant variation among sites that could not be attributed to forest type. Small
diameter logs in the logging regenerated forest lacked some apparent mature forest
specialists that were present in large diameter logs in the same forest type. This research indicates that large diameter logs have unique habitat qualities for saproxylic beetles,
and they are important in providing continuity of habitat for the re-establishment of
certain species following stand level disturbances, whether induced by logging or by
wildfire.
A precautionary and multi-scaled approach towards dead wood management is
advocated, with particular consideration of the temporal scale at which the dynamics of
the forests operate. In line with current conservation management strategies employed
and explored by Tasmanian forestry, retention of some trees during harvesting to
improve stand structure complexity and future dead wood supply is strongly
recommended as one means of mitigating potential negative impacts. The planning of
tree retention should aim to provide sufficient oldgrowth features, and sufficient
quantity and continuity of dead wood types, throughout successive forest regeneration
cycles for conservation of dead wood dependent biota. At the landscape scale, managing
the production forest matrix as a habitat mosaic through diversifying silvicultural
regimes is also recommended.

Item Type: Thesis (PhD)
Keywords: Beetles, Forests and forestry, Eucalyptus
Copyright Holders: The Author
Copyright Information:

Copyright 2005 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:

For consultation only. No copying permitted until 12th November 2006. Thesis (Ph.D.)--University of Tasmania, 2005. Includes bibliographical references

Date Deposited: 04 Feb 2015 23:31
Last Modified: 24 Aug 2016 04:06
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