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Old growth forests are important
as much for what we cannot see and know about them as
they are for what we do know and value. Because we do not know
all there is to know about these ancient forests we should be
very careful how we treat them.
Extinctions have always been a
part of evolution, but what's new is the current rate of extinction
due to the rapid growth of the human population and natural
habitat destruction by humans.
In the 200 years since Europeans arrived in Australia the rate
of change to the natural environment has accelerated far beyond
the ecosystems' ability to
adapt to the rapid change. Old growth forests provide largely
undisturbed habitat and are havens for indigenous
flora and fauna. Large reserves are needed to support these
flora and fauna populations.
Foresters often say that there
have been no recorded extinctions due to logging. This claim
should be treated with caution for several reasons:
- Forest ecosystems contain many different
types of organisms and very few have been monitored for any
length of time.
- The absence of recorded extinctions is not
in itself proof that there have been no extinctions.
- The absence of recorded extinctions does
not mean that the risk of future extinction is low, especially
under changing environment and management conditions.
The conversion of State
forests from old
growth to regrowth
is continuing and the effect on old growth dependent species
cannot yet be determined. (The
Resource Assessment Commission, Forest and Timber Inquiry Final
Report, 1992)
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SIMON NEVILLE
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"... local extinctions
are widespread in the [South West forest] region, such as
the woylie and numbat from the Blackwood plateau...The presumed
reason for the disappearance of the bilby, the burrowing bettong,
the rufous and western bristlebirds, the noisy scrub-bird,
western whipbird, ground parrot and the malleefowl, is the
degradation of their habitat through frequent fires...It is
clear none of these species would be able to survive under
present forest management conditions... Many endangered species,
such as the chuditch, numbat, woylie, tammar wallaby and yellow-bellied
frog, are likely to be directly affected by forestry operations.
Other species which were relatively widespread in the region
have suffered significant decline and are now uncommon, such
as the brush-tailed possum, brush wallaby, quokka, water rat,
brush-tailed phascogale, red-tailed black cockatoo and Baudin's
white-tailed cockatoo"
Dr Jean-Paul Orsini, National
Threatened Species Network, 1994.
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Hollow-dependent
species
Nineteen mammals and thirty one
bird species that live in the forest require hollows for breeding
and shelter. The CALM practice of leaving four habitat trees per
hectare is based on a single study for one species and has come
under criticism from scientists for being inadequate.
(Technical Advisory Panel to the EPA, Report on
CALM' s Proposed Forest Management Plans, 1992)
Suitable hollows first develop in jarrah trees
at around 300 years of age and at around 200 years for marri
trees. The youngest karri tree found to have hollows was 168
years. The estimated average age of jarrah trees that possums
used was 500 years and 400 years for marri trees. (Wardell-Johnson
(CALM) and Nichols, 1992)
For parrot species the estimated age of trees
was 275 years and for cockatoo species, 446 years.
(Mawson & Long, study published in EMU, Royal Australian Ornithologists
Union, 1994) Current logging practices have such short
rotation periods that they do not leave enough time for hollows
to develop. The rotation period for logging in the jarrah forest
is 150 years, and 100 years in the karri forest.
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"Species
Extinctions and the South West Forests"- RTF file |
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"Forestry
Effects - non-existent until extinction occurs?"- RTF
file |
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"Logging
rotations in south-west forests "- RTF file
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" A major conclusion from our study was that the array of issues
associated with the retention of trees with hollows within Australian
wood production eucalyptus forests are considerably more complex
than presently appreciated by the majority of forest and wildlife
managers. Indeed it appears likely that most existing prescriptions
for the retention of trees with hollows in logged sites are
inadequate and many may not either; ensure the long term perpetual
supply of a range of types of hollow trees and/or provide the
necessary habitat conditions to support viable populations of
some species of hollow dependent fauna."
Dr P. Gibbons and Dr D.B. Lidenmayer, Forest management
and the retention of trees for the conservation of hollow-dependent
fauna, 1995.
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