Forest list archive: msg00206

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Re: Old growth/ancient forests



Old-growth as a term in forest ecology developed in the Douglas-fir
forests of the Pacific Northwest of the USA. The term has been used by
foresters in some parts of Australia for many years but this was usually
to describe forests that were putting on little  timber increment, a much
narrower concept than that developed in the Pacific Northwest.
The term became part of the official forest policy vernacular in
Australia when it was used in the National Forest Policy Statement.
However, it is my belief that this was done without much thought to how
the concept applied in eucalypt forests particularly those that are
subject to low to moderate levels of disturbance (mostly fire) at
relatively frequent intervals (which is the majority of the area of
eucalypt forest).
Because it wan't precisely defined the term was fairly readily accepted by
both sides of the debate, industry and environmental groups because they
were really talking about different things. Industry wree thinking about
forests with lots of old trees (of which there are relatively few) and
environmental groups about forests that have been relatively little
disturbed by humans with chainsaws (of which there is still a
considerable area).
As the group working on Ross Peacock's study found, however, it is very
difficult to identify cut of points in structural and compositional
condition to defien old-growth forests in forests disturbed on  20-200
year intervals. This is a problem that has also been encountered in
trying to apply the old-growth concept in many other forest types from
Eastern Oregon and Washington to the boreal forests of Canada.
In relation to the application of the term in tropical forests. The term
does not appear to have had much application in the tropics, although
this may change as the term is being used more extensively in many
situations, for which it may or may not have valid application. I disagree
with the two posts that suggests 'virgin' forest as an alternative.
Virgin forests are those undisturbed by humans, and may not necessarily
be old-growth. The most analagous term in wide usage in the tropics would
be 'primary' rainforest, as opposed to secondary forest which has
developed after a large-scale disturbance.
Cheers


Dr. Rod Keenan
Officer-in-Charge,
Tropical Forestry,
Queensland Forest Research Institute,
DPI-Forestry, P.O. Box 210, Atherton, Q. 4883
Australia
TEL: 61 (0) 70 911844
FAX: 61 (0) 70 913281
keenanr@planet.mh.dpi.qld.gov.au



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