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| Life of a Forest |
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Copyright © 2004 Forest Management - Department of Environment and Natural Resources
Government of the Northwest Territories |
New
forests regenerate and grow naturally in burned and harvested
areas or they can be regenerated artificially through planting
or seeding after harvesting.
Immature
forests are generally the healthiest forest and grow at the
fastest rate. Saplings and shrubs abound and provide an excellent
food source for many animals.
In
the Northwest Territories, mature forests range between 90 and
150 years of age. Although trees may have the potential to grow
even older, a high fire frequency generally limits the age to
which trees grow. As one moves further north in the Northwest
Territories, the average age of trees increases as fire frequency
decreases. In many areas of the southern NWT, forests are composed
of spruce-aspen mixtures which are less prone to many types
of natural disturbance.
As
trees age, they become more susceptible to insect damage, tree
diseases and climactic stresses. At this stage, trees begin
to die, fall over and cover the forest floor. When a forest
reaches this stage in succession, the dead standing trees are
home to many insects and birds, all the while becoming more
prone to intense forest fires. 
Fire
is the dominant natural disturbance in the boreal forest. Fire
has sculpted the forest creating an abundance of habitat for
plant and animal life. Forest fires are one of nature's ways
of replacing older forests with younger, healthier trees. Some
trees, such as the jack pine, lodgepole pine, and even black
spruce are adapted to wildfires in that intense heat is required
to open most of their cones and release seeds.
Whereas
forest fire is the dominant natural disturbance in most of the
Northwest Territories, flooding is also a major disturbance
in the Mackenzie Delta region. During the spring floods of the
Mackenzie River with its maze of channels, many trees along
the banks of the channel are scoured out and knocked over by
debris floating down river. Low lying areas are filled with
floodwater, drowning flood-intolerant trees in the process while
sedimentation builds up over previously growing plants.
Most
of the trees harvested in the Northwest Territories are used
to make lumber or for firewood. Generally, trees in burned areas
are used for firewood while trees in mature stands are used
for lumber and other wood products.
Tree
insects and diseases are most common in older stands of trees
which are not as resilient as young stands of trees. These agents
of change help in recycling aging forests. Insects are important
in decomposing organic matter. Forests damaged by insects and
disease are more susceptible to wind and forest fires.
The
forest soils of the north are typically thin and poorly developed.
As a result, many trees, which are shallowly rooted, are susceptible
to being blown over during strong winds. In some cases the winds
are strong enough to break insect and disease-weakened tree
stems, and in other cases will uproot shallowly rooted trees
such as white spruce. The result of windthrow and blowdown disturbance
is that forest openings are created for regeneration of plants.
