Climate change will test resiliency of our ecosystems

Climate change will test resiliency of our ecosystems
Apr. 8, 2006. 01:00 AM


Eight years after Eastern Ontario's greatest disaster, the ice storm of
1998, injured trees are still dying.

In the Thousand Islands area where I live, the trees, stripped of much of
their canopies and having struggled through three, non-consecutive summers
of drought, are stressed out. One by one, they've given up, no longer able
to defend themselves against insects, disease or simply fatigue.

This doesn't mean the forests are disappearing. Far from it. But as climate
warming is starting to alter the mix within forests — with wildlife,
insects, plants and diseases migrating with temperature changes — the
ice-storm deaths are one more instance of changing times.

And sometimes, as if to remind us that change doesn't travel in a straight
line through ecosystems, but rather reverberates like sound, producing
different effects in different directions, the death of a tree can be
indirect, the result of changes produced by changes.

Such is the case with sugar maples. They are vulnerable to attack by the
sugar maple borer, an elegant looking, black-and yellow-beetle about 2.5
centimetres long.

With forest canopies stripped, much more sunlight gets in, producing ideal
conditions for the beetles. They remain more active than normal because
canopies haven't fully recovered.

They lay eggs under bark scales or in cracks and, after the larvae hatch,
they tunnel under the bark on the south side of sugar maples, and eventually
dig into the sapwood. They overwinter for two years, reaching a length of
five centimetres, and finally emerge as adult beetles.

The bark over the tunnels rises into ridges and cracks open. Rot can set in,
and when it does, the tree will snap in a high wind, as did the one in the
photograph.

This particular tree snapped about a year and a half ago. It had been 10.5
metres tall and is 29 centimetres in diameter at the base. Stubs of
branches, stripped by the ice storm, can be seen, as well as small new
branches that have grown below the break as the tree struggles to survive.
Struggle as it may, however, this tree is doomed. It's too weak and denuded
to last.

It is but one example of the complex shifting that's beginning in forests,
And it's so complex no one knows for certain what the long-term results will
be. Already, ravens have expanded south, while southern flying squirrels
have moved north, as have cerulean warblers.

Meanwhile, temperatures continue to rise. Last winter was the warmest since
Environment Canada began recording national temperatures in 1948. It was 3.9
degrees Celsius above normal, 0.9 degrees above the previous record set in
1987.

"That's remarkable," climatologist Bob Whitehead noted in a Star story last
month. It was the kind of winter that normally would occur once in 100
years. However, he said, it fit very well with the trend for global warming
projected by Environment Canada's computer models.

There's no reason to believe that the trends we're seeing won't continue,
that records won't continue to be broken. After all, carbon dioxide, the
main greenhouse gas, remains in the atmosphere for 50 to 200 years, and more
emissions are being added every year.

With all this change and uncertainty, however, one absolute remains:
Ecosystems will need to be resilient in order to cope. And resilience comes
from biodiversity. So, we need as much research as we can get, aimed at
understanding how biodiversity can be maintained.

That's why it was so blockheaded of Ontario Opposition Leader John Tory to
ridicule the government at Queen's Park for giving a grant to an
evolutionary biologist who is studying southern flying squirrels that have
reached Algonquin Park from the south. The biologist is examining their
adaptive ability.

It's also why, last week, it was so ideologically myopic of Prime Minister
Stephen Harper to cancel the One-Tonne Challenge program, aimed at reducing
greenhouse gas emissions, without at least replacing it with another program
similarly directed at individual Canadians.

In addition to research, we need public awareness of both the causes and
effects of global warming, as well as road maps for individual action.


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Cameron Smith can be reached at camsmith kingston.net.