Forests - General
“The result is Athens is now like one of the small islands, the bare skeleton of a sick body with barely any flesh on it. In the early days the land was unspoilt: there was soil upon the high mountains and what we now call scrub had fields of rich earth. The year’s rain did not as now run off the bare earth into the sea but the water coming down from the hills was preserved and fed springs and rivers.” Plato (429 - 347 BC) commenting on deforestation in ancient Greece.
It has been well known for millennia that forests are environmental regulators.
- They moderate temperatures and humidity
- Forests convert carbon dioxide to the oxygen we breathe
- They are a critical part of the water cycle
- Their root mass holds the rain and soil preventing rapid runoff and flash floods and assuring year around clear running streams
- Forests form the habitat that accommodates a huge variety of wildlife, micro-organisms and flowers and vegetation.
Like the ancient Eastern Mediterranean region, Canada was once home to great forests that represented huge standing and growing stocks. Today, most of the old growth has been cut and the soil upon which it once stood has been severely degraded. The resulting loss in soil fertility combined with other stressors such as pollution and climate change have reduced the size of our standing stock and the rate at which it grows.
44% of Canada’s landmass is covered by forest which, like our agricultural lands, is subject to the constraints of soil and climate. Of the 453 million hectares of forest, 244 million hectares have commercial potential.
Given the harshness of the Canadian environment, our forest lands are considerably less productive than those in more temperate climates. As in agriculture, we have a lot of surface area but the productivity is much lower than in many other regions of the world.
- In the Brazilian rainforest, the average growth of biomass per hectare per year is over 10 cubic metres
- A variety of Amazonian red oak can produce 50 cubic metres annually
- The average forest biomass productivity in the USA is 5.3Cu.m
- In Canada the figure is 1.7Cu. m annually
- Above the 55th parallel, 0.5Cu. m per hectare per year is all the ecosystem can produce
A forest is not merely a stand of trees, it is a community of arrays of plant and animal life forms. Once the trees are removed, the community is drastically altered and largely destroyed. Although trees may grow again, the biological structures will take many generations to recover. Consequently, the replacement forest will not be as healthy or productive for centuries.
Forests are an irreplaceable economic, cultural and environmental asset. We need to reduce our exploitation of this critical resource to below sustainable levels.
Forests - Advanced
When Europeans arrived in North America in large numbers in the 1700s, they believed they were entering a New World of virgin forests. What they were really seeing was a highly managed eco system which had largely gone “natural” over the preceding century due to the huge population decline of the native peoples.
As their societies collapsed, the Amerindians were unable to maintain the management of the forests into areas very favourable for their wild game and for orchards of fruit and nuts. As their numbers declined (~ 90% population drop from 1492AD– 1650AD), they also had a much smaller impact on the land. Consequently, nature resumed its normal pattern of working towards a climax forest which is a forest where the succession dynamics have ceased and the forest establishes a stable mix of tree species. Reaching equilibrium in age and species distribution - a climax forest – takes about 1000 - 2500 years to achieve.
Amerindian forest management was less of a factor in Canada than in the more densely populated areas of the American east coast which itself was a pale version of the terraforming which occurred in Central America during the height of the Mayan and Aztec civilizations.
With the arrival of Europeans, management and large scale destruction of the forests began in earnest. Below is a table of the changes in biomass for various species in Canada from the period 1500 AD to 1970.
Biomass change is actual wood volume as opposed to the number of trees. (many young trees would have far less biomass than one mature tree)
|Hudson Bay Plain||371||16||4||0.0435|
As settlement moved west and north through the great eastern forests, vast swaths of valuable hardwood forests were cut to make way for farms and for the export of the precious logs and lumber. Although records are not available, it is certain that a huge amount of soil would also have been lost due to clear cutting and burnoffs. This would severely impair the ability of the forests to recover and regenerate and it would also have meant a very short life for farms established on the more marginal soils of the Canadian shield.
According to Global Forest Watch, over half of the forests in 7 of Canada's 10 major forest regions have been fragmented by roads and other access routes.
About three-fifths of the eastern Carolinean forests and the aspen forests bordering the prairies have been converted to agricultural or residential land.
Coastal forests of British Columbia—home to one-fifth of the remaining temperate rainforest—are under widespread development pressure. Over 80% of this forest has been allocated to logging companies (through tenure areas managed for timber harvest, which includes extensive tracts of forest not destined for cutting). Nearly half the forest is fragmented by roads and access routes, in blocks less than 200 km2 in size.
Since the early days of reckless exploitation, vastly more care has been put into the management of Canada’s forests. But their health can be no better than that of the soil and ecosystems in which they grow and the stability of the climate. Forests cover almost 50% of the Canadian landmass and the climate that landmass is experiencing is changing dramatically. Temperature and water cycle changes are placing extreme stress on many areas of our forests and opening the door for invasive species attack for which the forests have little defence.
The pine beetle is the best example of a destructive invasive species and it has laid billions of trees in BC to waste. If it manages to cross into Alberta, it may well threaten all of Canada’s boreal forest. Given climate change and the impacts of invasive species, mortality and species equilibrium are open questions
Canada has 13 Forest eco zones
|Name||Total Area||Forest Area||Share %||Volume|
|‘000s Sq km||‘000s Sq km||%||billions cu m|
|Mixed Wood Plain||195||31||16||0.212|
Forest Biomass Growth Rates
|Brazilian rain forest||Average USA||Average Canada||Average above 55 deg Lat|
|10 cu m biomass growth/hectare/year||5.3 cu m/ha||1.7 cu m/ha||0.5 cu m/ha|
Growth rates of forest biomass vary dramatically around the world and in Canada as well. In terms of standing stock, the biomass per hectare ranges from 158 tonnes in BC to 8 tonnes in the Yukon(lower Arctic) with a Canadian average of 59 tonnes.
Forests - Reference
Forest Mapping by GoogleRead more
Forest and logging book listRead more
|The Forest Shop|
Canada's national forest inventory - numbers and mapsRead more
|Canada's National Forest Inventory|
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Brazil’s vast forests lost some legal protections last week, but less than environmentalists had feared.
A number of products related to Global Forest Watch Canada's work are available to downloading and/or ordering. These products include maps, reports, photographs, data, and satellite imagery.Read more
|Global Forest Watch Canada|
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