Fed: Canberra's trees reaching age limits - scientist

AAP General News (Australia)
04-21-2004
Fed: Canberra's trees reaching age limits - scientist

By Denis Peters

CANBERRA, April 21 AAP - Canberra, the planned city which likes to call itself the
bush capital, is about to lose large numbers of its trees, scientists believe.

The danger will come not from bushfire but simply from many trees reaching the end
of their lifespans.

"There are approximately four planted trees for every three people in Canberra but
many are coming to the end of their safe life and are more likely to pose a threat to
the public," Australian National University (ANU) forest expert Cris (Cris) Brack said
in a statement.

Dr Brack said the capital, designed by American Walter Burley Griffin and founded in
the 1920s, faced either a huge repair and replanting program, or a serious public safety
issue.

"No tree will remain beautiful or a low public safety risk indefinitely but the harsh
climate in Canberra means that the city's trees may partially die or become unsafe even
earlier than in a species' traditional life cycle," he said.

"Water restrictions and the drought may mean that the loss of aesthetic value and safety
will be accelerated."

Dr Brack said many inner city exotic trees were planted about 70 years ago and traditionally
had a safe age of 70 to 100 years.

In the northern suburban area of Belconnen, eucalypts with a safe age of 50 years had
reached their limit.

Dr Brack said trees were a fundamental part of Canberra and there had been an active
planting program since the city's inception.

"We need to plan now for what we want our city to look like in 50 or 100 years, to
keep the diversity and colour."

Dr Brack suggested variety was the key to the future but the number of species featuring
in Canberra's streets in the future could be smaller.

"The tree mix we have, the mix of species, is to an extent just an artefact of the
basis of the knowledge back at the turn of last century," he said.

"(At that time), we only had evidence of how trees grew in cities from the North Americans
and the Europeans.

"We didn't know what Australian species would do well in cities."

He said there were as many as 150 different tree species in the older, inner suburbs of Canberra.

In the future, the range could be down to just 20 tried and true species.

AAP dep/sw/cmc/tnf

KEYWORD: TREES

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