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Application of island biogeographic principles to the selection and management of Tasmanian dry sclerophyll reserves


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Bosworth, Peter, Dorney, Neralee and Tarran, Anne 1976 , 'Application of island biogeographic principles to the selection and management of Tasmanian dry sclerophyll reserves', Coursework Master thesis, University of Tasmania.

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Throughout the world today the areas occupied by many natural habitats
are undergoing two types of change. Firstly, the total area occupied
by natural habitats is shrinking and secondly, formerly continuous
natural habitats are being fragmented into disjunctive pieces. Both
these processes have important consequences for the future of the world's
plant and animal species. To preserve natural diversity it is critical,
therefore, that the present methods of conserving wildlife be reviewed
and that careful planning of reserves be undertaken, based on appropriate
ecological principles.
A comparison may be drawn between a nature reserve and an oceanic island
from the point of view that each is surrounded by a zone of inhospitable
habitat which acts as a barrier to dispersal for many species. Considerable
progress has been made over the last decade towards an understanding of
the functioning of oceanic island systems, particularly as regards the
maximum number of species that an island may support without threat of
extinction to any species. Application of this knowledge may provide
a basis for understanding what to expect from reserves and, most importantly,
may offer a method for determining the minimum size of a reserve needed to
maintain the diversity of plant and animal species characteristic of that
habitat type.
To date, studies in the field of island biogeography have concentrated on
natural islands with little attention given to the habitat islands created
by man in clearing land for agricultural and commercial activities. The
aim of the present study is to investigate the species-area relationship
for a series of islands of dry sclerophyll forest on the Tasmanian mainland
and to compare the findings of this study with previous studies undertaken
on oceanic islands.
The implications of establishing a similarity between the two types of
islands are far-reaching. It is hoped that this and other similar studies
will serve to emphasize the special features of habitat islands and that,
in future, more attention will be given to the planning of reserves in
accordance with island biogeographical principles. Thus determination
of the most suitable size and shape of a reserve, as well as planning for
an integrated system of reserves which functions in the most effective
way possible, may be achieved.

Apart from being of general significance the study is also important at
the local level. In Tasmania, as in other places of the world, the natural
environment is being fragmented as land is cleared to make way for urban
and rural development. In the past the dry sclerophyll forest has been
the habitat type most heavily exploited for these purposes and, more
recently, has been subject to further pressure from the woodchip industry.
Furthermore, whilst provision has been made for the conservation of
other vegetation types within the State adequate reservation of areas of
dry sclerophyll forest has failed to occur. For these reasons it is
imperative that the present situation regarding the dry solerophyll
reserve system in Tasmania be examined and the need to establish
additional reserves be investigated as soon as possible.
The desirability of having large-sized reserves to ensure maintenance
of species diversity has been emphasized by several authors recently
(Willis 1974; Diamond 1975; Moore and Hooper 1975; Sullivan and Shaffer
1975; Terborgh 1975). Few authors, however, have actually suggested
dimensions. Unfortunately, it is extremely difficult to demonstrate
experimentally the concept of minimum reserve size; nevertheless there
have been some attempts, using a variety of approaches, to determine the
size of a reserve required to maintain a particular taxon or group of
species. These studies will be discussed further in the following
chapter but it is important to emphasize that none of the authors have
adopted the approach of the present study, in making use of the island
nature of reserves and applying the corresponding biogeographic principles.
In order to understand why the field study was conducted and how the
results of the study could be used to determine the area requirements for
a dry sclerophyll reserve, it is necessary to trace the development of
the theory of island biogeography and to examine the arguments which have
been advanced in applying these principles to the design and management of
nature reserves. This review introduces the field study where the planning
and executing of the study are described in detail.
To develop a method for determining the size requirements of a reserve
it was not necessary to conduct lengthy studies and, accordingly, all
field work could be completed within a year by three workers. The
apparent brevity of this study sets it apart from other more detailed
pieces of scientific work but does not detract from the validity of
the methods used or from the results obtained.

The results of this study are analysed and a minimum area, which would
preserve the diversity of dry sclerophyll species,is suggested. The
exploitation of the forest, both past and present, is then examined
and the existing reserve system is also assessed. The need for augmenting
this system is emphasized and some areas, which in biological terms may
be appropriate for reservation, are discussed. It should be pointed out,
however, that there are many other aspects which need to be considered
before reserving an area but which are essentially beyond the scope of
this report. The responsibility of dealing with these factors lies
with those agencies which are involved in the planning Of reserves at
the government level.

Item Type: Thesis - Coursework Master
Authors/Creators:Bosworth, Peter and Dorney, Neralee and Tarran, Anne
Keywords: Nature conservation, Biogeography, Forest ecology
Copyright Holders: The Author
Copyright Information:

Copyright 1976 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 (M. Env.St.) - University of Tasmania, 1977. Includes bibliographical references

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