THESIS ABSTRACT
An investigation into the effects of Chrysanthemoides
monilifera ssp. rotundata (Bitou Bush) infestation
and treatment on the vegetation community at Booderee National
Park.
Author: Kristen Elise Prattis
Year: 2004
Degree: BEnvSc (Hons)
Abstract:
The invasion of Chrysanthemoides monilifera ssp. rotundata (bitou
bush), is one of the most serious threats posed by a weed species
to the natural ecosystems along the New South Wales coastline. Booderee
National Park is one of the most important natural communities
in Australia, and bitou bush is the most significant weed within
the park and threatens its ecological integrity.
In an attempt to reduce the current infestations of bitou bush
within the park a number of control strategies have been utilized. These
include herbicide control with glyphosate, biological control
methods and the use of fire. An integrated control strategy
incorporating the use of all three of the above techniques is
presently recommended. However, the impacts on the species
composition of vegetation communities that have undergone any
of the various control strategies that exist for bitou bush have
been poorly studied.
This study is aimed at assessing the response of the bitou invaded
vegetation community to the application of a variety of bitou
control strategies. The first study investigated the short-term
response of the bitou infested community to a spray with the
herbicide glyphosate®, and the subsequent application of
a controlled burn. The second study compared four habitats
including; an undisturbed native habitat, an untreated bitou
infested habitat, a bitou infested habitat that had been treated
with a single spray of glyphosate from 2001 to 2002 and a previously
bitou infested habitat that had been treated with a spray-burn-spray
technique over three consecutive years commencing in 2000.
It has been found that the single treatment of a bitou infestation
without undertaking a secondary treatment is insufficient to
control the bitou infestation or encourage native regeneration.
There
was no significant difference in the abundance and richness of
native vegetation between the bitou infested and post-spray habitat
compared to the native habitat. This may potentially indicate
that an alteration in the leaf litter decomposition rates of
the habitat have occurred, which would affect the supply of nutrients
and organic matter to the soil.
Results indicate that a spray-burn-spray technique applied to
a bitou infested habitat is more effective than a single spray
treatment at decreasing the density of bitou and regenerating
native species.
However, full regeneration of the habitat
after bitou treatment may not be possible without restoration
occurring after the cycle of bitou treatment has been completed. Furthermore,
a number of weed species were found to invade the habitat after
the bitou was removed. To decrease the level of weed invasion
occurring in habitat after the bitou removal, it is recommended
that restoration measures be undertaken.
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