Media Clipping — Tuesday, December 18, 2001, The Halifax Herald

Forestry and the soil sustainability debate

By Paul Schneidereit

CLEARCUTTING is an ugly word and – immediately afterwards – an ugly sight.

But tramp through a clearcut area 10, 15 or 20 years after a harvest, as I've been doing this fall, courtesy of tours arranged by the Forest Products Association of Nova Scotia, and there's an abundance of healthy, growing young trees – of different species – on these sites.

My walks in the woods have been prompted by the ongoing public discussion – in this column space – of forestry that I began in the summer. For those who haven't followed the debate, Kermit deGooyer of the Ecology Action Centre and Steve Talbot, executive director of the association, each representing a sharply different point of view, have been our main participants.

Clearcutting was the opening topic of debate.

Trees, my field trips showed, were certainly coming back after clearcut harvests.

But, the basic question remained, was clearcutting a sustainable practice? Wouldn't taking all the timber, over time, rob the forest soil of its fertility?

To find some answers, I asked Mr. Talbot and Mr. de Gooyer to each recommend a soil scientist to interview.

Helmut Krause, a retired and well-known professor of forest soils at the University of New Brunswick, was recommended by industry. Taumey Mahendrappa, a senior soil scientist at the Canadian Forest Service (part of Natural Resources Canada) in Fredericton, was suggested by the ecologists.

Surprisingly, the two scientists turned out to be pretty much in agreement on most issues, including calling some environmentalists' claims unfounded and many of industry's harvesting practices harmful to the soil.

But the bottom line, they said, was that many studies show that clearcutting – if done properly under the right conditions – was a sustainable way to harvest timber.

The above proviso – if done properly under the right conditions – is extremely important in Nova Scotia, they said.

First, clearcutting must be stem removal only. What's called the "slash" – the tops and branches from the harvested trees – must be left behind, on the ground, to decompose, releasing nutrients back into the soil and keeping the soil temperature from rising. The worst practice, Mr. Mahendrappa said, was to remove the whole tree, then collect and burn the slash, robbing the soil and releasing carbon into the atmosphere.

Though there is always an immediate nutrient loss due to clearcutting, they said, given enough time, nutrient levels will come back.

Second, clearcutting is only advisable on the more fertile forest soils and in long-enough rotations – 50 years at the very least, said Mr. Krause. The specific waiting period depends on the unique characteristics of each stand.

Clearcutting trees on marginal soils – or harvesting trees in shorter rotations – is a bad idea, they agreed. Poorer soils cannot recover nutrient losses as readily, affecting regrowth, while short rotations don't give nutrients time to recover.

"The longer the rotation age, the better for the forest," said Mr. Krause.

Third, harvesting itself can also damage the forest by compacting the soil. As much as 30 per cent of a clearcut area can be affected by machine and vehicle traffic, said Mr. Krause. Tire rutting, soil compaction from skidders and logging roads all have a negative impact.

Protecting water courses and hillside erosion are also issues.

And acid rain, which is leaching calcium from the soil, is a critical problem in eastern forests, said Mr. Krause.

Following my talks with the scientists, Mr. de Gooyer asked that I speak to Minga O'Brien, a biologist and one of the authors of the recent GPI study critical of clearcutting in our forests.

She says arguments that clearcutting – in the right conditions – is a sustainable harvesting practice are problematic for several reasons. Studies she's seen are all short-term – under 100 years – so assessing any long-term impact on the soil is still "guesswork." And, she says, the specifics of actual harvesting rarely match the theoretical conditions referred to by the soil scientists. Soil science, she says, can't be looked at in isolation.

In a future column, we'll look more closely at her arguments.

Copyright © 2001, The Halifax Herald