Pine forests may
pollute more than traffic
By DENNIS
BUECKERT
OTTAWA (CP) - Coniferous forests around the world may be
emitting more smog-causing nitrogen oxides than traffic and
industry combined, suggests a report in the prestigious
journal Nature.
The report, released Wednesday, flies in the face of the
accepted view that forests reduce pollution by absorbing it -
a theory Canada relied on in demanding credit for forests as
pollution "sinks" under the Kyoto climate change accord. But
environmentalists aren't about to blacklist Scotch pine trees.
They note that forest emissions are part of a natural
balance that has existed since pre-industrial times and say
manmade emissions are behind most pollution and global
warming.
Scotch pine needles release nitrogen oxides directly into
the atmosphere when exposed to ultraviolet light, says a study
led by Perrti Hari of the University of Helsinki, Finland.
Nitrogen oxides are smog precursors: they combine with
other pollutants to form ground-level ozone, a major component
of smog.
The emissions from Scotch pines increase in proportion to
the amount of ultraviolet radiation they receive, says the
study.
"Although this contribution is insignificant on a local
scale, our findings suggest that global NOx emissions from
boreal coniferous forests may be comparable to those produced
by worldwide industrial and traffic sources," says the report.
Quentin Chiotti, a scientist with Toronto-based Pollution
Probe, acknowledged that forests contribute a variety of
chemicals to the atmosphere, but was surprised at the
comparison with traffic and industry.
"If I walk through a forest am I going to be at risk for my
cardiac and respiratory health? Unless it's a very unusual
forest . . . I can't imagine our health being at risk."
Even though the emissions may seem large when calculated
for the globe they have no local health effects because they
are diluted in the global atmosphere, he said.
Henry Hengeveld, a scientist with Environment Canada, said
emissions from vegetarian are part of a balance that doesn't
change much over time.
"They should be pretty steady at a pre-industrial level,"
he said.
What matters for human health is the increments to that
background level, he said.
Kevin Percy of the Canadian Forest Service in Fredericton
said he has problems with the suggestion that emissions from
coniferous trees could exceed those from traffic and industry.
"From my perspective, that would be pure conjecture at this
point."
Former U.S. president Ronald Reagan caused an uproar in
1980 when he said trees cause just as much pollution as cars.