Twelve thousand years ago, there were no forests in British Columbia. Glacial ice covered the land to a depth of thousands of metres. Slowly the climate warmed, the ice melted, and the glaciers retreated. From the south, from western refuges on Banks and Queen Charlotte Islands, and from the Nahanni, trees, shrubs and herbs began to return to land cleared by ice.
Animals followed their food supplies, insects pollinated flowers, fungi and bacteria broke down litter and enriched the bare earth. Slowly, new forests began to form.
Our magnificent forests of today are linked to those first early forests. Perhaps a hundred generations of trees separate the low elevation fire-regenerated forests of the Interior from those first colonizing individuals. On the coast there may be even fewer generations of some long-lived species because of the greater time between major disturbances.
The common thread that links the earliest trees to their current descendants is the complex biological molecule, deoxyribonucleic acid (DNA). This molecule contains the codes for growth, development and reproduction. Variations in its structure provide the wealth of genetic variation that we find in almost all living things.
Genetic variation is critical to the ability of organisms to accommodate changes in the environment. Geological history tells of many major and minor fluctuations in climate, even since the last glaciation. Cool summers were prevalent from 800 to 600 years ago, followed by a period of warm, dry summers until about a 100 years ago. Then a "little ice-age" saw glaciers advance once more. Now we are in another warming trend.
These fluctuations in climate mean that the offspring of long-lived trees often establish in very different environments than did their parents. As well, trees grow in a wide range of ecosystems and must accommodate daily, seasonal, and longer-term variations in environment. Maintenance of genetic variation is thus very important for the forests of British Columbia.
Funding for the Internet version was provided by Forest Renewal BC.
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Updated October 16, 2008