OUR AILING FORESTS -
Driving the Pacific Highway from the North Coast to Sydney, one can be excused for
feeling a warm glow at the vast expanse of eucalypt forest, with its pockets of dry rainforest
vegetation, but behind the leafy facade there is a different story. The stately old-growth
gum trees so familiar to us all is a critical element in the survival of many of our native
species. A wide range of animals, birds and reptiles depend on the hollows that develop in
these forest giants as they reach old age, an age that can exceed 200 years. In fact it will
take that long for many eucalypt species to become effective habitat trees.
One hundred and fifty years ago, new settlers from Europe began systematically logging
the prized cedar and hoop pine, both species sadly logged to the brink of extinction. It was
not until more recent times that the timber-getter's attention turned to the Australian
hardwood species of which the eucalypts make up a large percentage.
For the past 80 years forests have been systematically logged. In State Forests, past practice
has been to 'discourage' the growth of tree species that are unsuitable for saw logs. Old-
growth–habitat trees were seen as an impediment, taking up valuable space where young
trees could develop. Regular fire regimes and cattle grazing were encouraged in order to
'clean up' the understorey vegetation. In more recent times, an enlightened State Forests
have moved to protect what remains of these old-growth trees and, prior to logging, these
trees are marked with the painted letter H for habitat, and must not be touched. The keen
observer will also see other trees marked with R, this stands for Recruitment habitat tree,
and must also be left.
The recruitment tree is commonly a tree of medium size, possibly between 30 and 60 years
old, and is generally damaged in some way, making it unsuitable for harvesting. Invariably
that damage has resulted from earlier timber-getting exercises, the bole of the tree scraped
by machinery or a log being dragged from the forest.
In my opinion these damaged trees will never become effective habitat, as they simply will
not live long enough. The rotting portions will begin to burn out with the next bush fire,
and successive fires will progressively destroy the tree within the following fifty years. By
that time many of the remaining legitimate habitat trees will have succumbed to old age and
fallen, leaving a critical shortage of nesting habitat for our struggling wildlife.
We have upset the balance of nature. Survival of the fittest has always been the way of
nature, but nature has been manipulated by man's unthinking actions. There is also some
evidence that the Brush-tailed possum may well be on the way to becoming an
environmental pest (P. Edwards 2005). Not only is the possum better equipped to adapt to
change, even living with humans, but its natural predators, particularly the large owl
species, are all now threatened with extinction because their old-growth habitat is
disappearing, and many of the remaining hollows are occupied and fiercely defended by
possums. The explosion of possum populations in some areas is also suspected as having a
direct impact on some threatened bushland bird species, as they are known to predate
nestlings of some larger birds whose nests are built on the sturdier tree branches, easily
accessible to possums.
The depressing part in all this is that it will take over a hundred years for natural
regeneration to occur, by which time it could well be too late for many of our larger owls,
cockatoos and a range of threatened fauna such as gliders. It is vital that we preserve as
much old growth habitat as possible, and ensure that an effective recruitment habitat tree
program, involving healthy trees, is introduced.
-John Edwards
THE DECLINE OF HABITAT