By Richard Black
Environment correspondent, BBC News website
"What is wrong with clear-cutting? I've asked many environmentalists to actually tell me, ecologically, what is wrong with clear-cutting; and I have yet to receive a coherent answer."
It seems unusual for an ecologist to advocate the mass clearance by brute force of large tracts of trees - but that is exactly what Hamish Kimmins is advocating for certain kinds of forest.
I am sitting with Hamish, a professor at the University of British Columbia (UBC), among trees in the south-east corner of Vancouver Island on Canada's west coast, discussing sustainable forestry for the BBC World Service One Planet programme.
As I am to discover, "sustainability" is an issue with many dimensions here.
It is warm and dry on the east side, and we have seen mixed forests including Douglas fir, spruce and cedar. But the other side of the island, where the Pacific winds make landfall, is home to a very different ecosystem - much wetter, with forests dominated by the coastal western hemlock tree.
Hamish believes that different types of forest benefit from different kinds of management. Some may flourish with selective logging; others need clear-cutting, however destructive it may seem.
The key, he believes, is to match the style of logging to the disturbances the forests would experience in nature; dry forests might have regular sweeping fires, wetter ones merely the occasional landslide or treefall.
"We're an emotional species: we make the big decisions in life, we fall in love, buy our clothes, choose where to live, with our eyes and our heart," he says.
"Foresters must consider aesthetics, spiritual values and how people feel about things.
"But on the other hand, citizens have a responsibility to balance their emotional response to the forest against a respect for ecology, a respect for nature, so that we can maintain a wide range of resources and ecosystem conditions far into the future for future generations."
A couple of days later I get to see some of the arguments up close.
Andy MacKinnon and Allen Banner are ecologists employed by the British Columbia (BC) provincial government to study and map forest types across the province.
I meet them near Bella Bella, halfway up the BC coast, in what has become known as the Great Bear Rainforest. They need to cover a lot of ground, and a helicopter is the only option.
Dry Canadian humour shines through our safety briefing from pilot Tony Walker. We are enjoined to save him paperwork by not walking into the tail rotor, but the good news is we can order pizza on the emergency satphone should we get stranded.
Then, in a magical morning mix of bright sun and curling mists, we are quickly up and flying over a dazzling sequence of small islands broken by spectacular inlets and fjords.
Subtly different colours between the stands of trees indicate various mixes of species, and demarcate areas which have already been logged from those that remain virgin forest.
The occasional bald hilltop shows recent clear-cutting; and soon we come across selective logging too, using the most modern of tools.
As Tony circles high above the slopes, lower down we watch a giant orange heavy-duty helicopter extracting trunks from the forest one by one, and dumping them in the nearest inlet.
This is heli-logging - minimally disruptive to the forest, in theory, because it needs no roads or bulldozer tracks. It is clearly expensive though, and companies make money by selectively extracting cedar, the most valuable species; and here lies the system's flaw, because young cedar need ample light if they are to survive.
"Regenerating these sorts of stands isn't a problem. Most of the saplings that are growing on this site won't have been planted, they'll be regenerating naturally," Andy explains after we have landed in a tract of land that has been clear-cut several years before.
"If you're making an opening large enough, like the one that we have here - I can see here there are a number of cedar saplings that are growing on this site; you'll get natural regeneration of western red cedar and probably get back a mix which is not too different from the one you took out in the first place.
Helicopters extract just the valuable cedar trees
"On the other hand, it's worse for wildlife and visuals; but if you make the openings small enough so they don't get a lot of light in, you'll probably convert those stands to second-growth stands without cedar in them."
And what is sustainable about a kind of management which denudes the forest permanently of its most iconic species, and one which is key for the cultural life of First Nations, indigenous peoples who have lived here since the end of the last Ice Age 10,000 years ago?
End of hope?
Forestry has not always been conducted in British Columbia with any regard for aesthetics or ecology.
European settlers arriving in the early 1800s found unimaginably vast areas of virgin forest ripe for plucking - and pluck they did, rapaciously, turning logging into BC's biggest industry.
A series of legal reforms have created a system which in theory ends the years of pillage in favour of more sustainable practices.
In the Great Bear forest, a decade-long dispute between industry, environmental groups, First Nations and the government has ended with an agreement on conserving certain areas and practising ecosystem-based management in the remainder. First Nations have considerable rights over land usage.
Forests elsewhere are allocated to logging companies according to rotating concessions, and companies are obliged to replant areas they have logged.
What alarms environmental groups is a recent change in regulations which allows companies to decide which management methods to use in their concessions. They are supposed to take ecology into account; but if they do not, the damage could show up only years down the line.
A two-hour drive inland from Vancouver city up the valley of the Fraser river brings me to the town of Hope; though for my companions, from the Western Canada Wilderness Committee and the David Suzuki Foundation, the name is an irony.
Here, they believe, is the end of hope for Canada's population of northern spotted owl (Strix occidentalis caurina). Once home to several hundred breeding pairs, numbers fell by half during the 1980s, and are now reckoned to include just 17 individuals.
"The spotted owl is an old-growth-dependent species," explains Gwen Barlee, policy director for the Wilderness Committee.
"The fact that we're down to just 17 shows us not only that the species is in trouble, but the ecosystem is in trouble. Here we are in a special resource management area for spotted owl, and the government has allowed logging in that area."
And logging there obviously was, and clear-cutting at that - probably the worst option for the spotted owl. The hillside forest was basically gone, with only a few isolated clumps of straggly trees left.
The globally recognised Red List of Threatened Species is unequivocal about the threat to the spotted owl: habitat destruction and logging.
So how can it be that a government publicly committed to sustainable forest management could manage its forest in such a way that species flirt with local extinction? What kind of sustainability is that in a country which is a fully signed-up member of the UN Convention on Biological Diversity?
The government contends that a much larger spotted owl population exists in California, and that the situation is more complex than it looks.
"Whether you would absorb the cost of foregoing logging over large areas, which is part of the economy of the province, to support a population at the edge of its range is a matter of intense debate, and that will be repeated with a number of other species in the province," says Bruce Fraser, chair of the Forest Practices Board, the provincial government's watchdog.
Icon in decline: The northern spotted owl
"Stopping logging in the Fraser Valley would have huge implications for a large number of people; so those kinds of decisions don't happen just because we have signed a rather general international convention."
Here, sustainability of the local wildlife is being set against economic sustainability of the local community - and the logging companies which have traditionally wielded much influence in political circles.
As times change, says Hamish Kimmins, society's expectations of forestry change too, and forestry has to adapt.
"Back in the old days, the values that people wanted were timber, employment and wealth; and that kind of forestry gave the people what they wanted.
"Now society wants many other additional values: biodiversity, carbon storage, water, protection of nature, aesthetics, spiritual values; and that means forestry has to change and has to adopt different methods."
In British Columbia, it seems, society has yet to work out which values it wants most; and the clash between strands of society, and various definitions of sustainability, awaits resolution.
One Planet from BC, Canada, is broadcast on the BBC World Service from Wednesday 4 to Friday 6 October.