2. Geology of
zones of Quebec
In order to begin to understand
the diversity of organisms and ecosystems that exist in Quebec, we have
to have to look more closely at the physical features of Quebec and
at the geological events that help to define them. The descriptions
of the geology and vegetation zones of Quebec have been compiled from
the Quebec Convention on Biological
Diversity, Implementation Plan and from the introductory chapter
of the Atlas of Breeding Birds
First, let's look at Quebec
as a whole: it is a land mass covering 1.67 million square kilometres.
Understandably, such a huge area of land will be diverse in both climate
and geology, factors which influence how much diversity exists in a
given place. Quebec is also a peninsula, surrounded on 3 sides by salt
water (Atlantic Ocean, Labrador Sea and Hudson Bay) and divided by the
St. Lawrence river one of the world's largest freshwater river systems.
geological regions of Quebec
Quebec's geology has been
influenced by early geological events and, most recently, by the last
glaciation that ended over 10 000 years ago and covered most of Quebec
in giant sheets of ice. In the last 3000 years, Quebec's main vegetation
zones were established. There are three main geological regions in Quebec:
the great igneous plains of the Canadian Shield, the mighty Appalachians
in southern Quebec and the St. Lawrence lowlands that lie between
Covering over 95% of Quebec,
the Canadian Shield contains some of the oldest igneous rocks
in the world, dating back to the Precambrian period, over 1 billion
years ago. The Canadian Shield is generally quite flat and exposed,
punctuated by the higher relief of mountain ranges such as the Laurentians
in southern Quebec, the Otish Mountains in central Quebec and the Torngat
Mountains near Ungava Bay. The topography of the Shield has been shaped
by glaciers, which explains the glacial deposits of boulders, gravel
and sand, and by postglacial seawater and lakes which left thick clay
deposits on some parts of the Shield. The Canadian Shield also has an
intricate hydrological network of over a million lakes, peat bogs, rivers
The Appalachian region
of Quebec is comprised of a thin strip of weathered mountains along
Quebec's southeast border. The Appalachian mountain chain is actually
a long range that runs from Alabama north to Newfoundland. In between,
it extends into Quebec for about 800 km, from the Monteregians to the
Gaspe peninsula. The rocks of this range are sedimentary, dating back
to the Paleozoic era, 250-500 million years ago. In western Quebec,
the mean elevation is about 500m, while in the Gaspe peninsula, the
Appalachian peaks (particularly the Chic Choc mountains) are some of
the highest in Quebec, surpassing 1000m.
The St. Lawrence lowlands
are comparatively tiny in size (about 17 280 square kilometres) but
disproportionately important in that they contain most of the human
population of Quebec. The lowlands actually consist of three parts:
the central lowlands, or the St. Lawrence Plain, a wide and flat triangle
extending from Cornwall to Quebec City, the lowlands around Lac St.
Jean and the east St. Lawrence lowlands which encompass the lower North
Shore and Anticosti Island. The St. Lawrence Plain is almost entirely
flat because of the clay deposits left behind by the Champlain sea (which
once covered all of Montreal). The relief is broken only by the weathered
Monteregian Hills, which are composed of entirely different, and much
older, rocks. The St. Lawrence Plain will be the focus of much this
website because it is a region of high species and habitat diversity
and because the area has been studied extensively, relative to the rest
vegetation zones of Quebec
Due to both the geology of
the province and its different climates, a number of broad vegetation
zones in Quebec have been classified. The zones, listed in order from
the most northern to the most southern, are:Tundra, Taiga,
Boreal (coniferous) forest, Mixed forest, and the
Tundra is a vegetation
zone associated with arctic and alpine areas of the Canadian Shield.
The vegetation here endures the harshest of climates, the annual mean
temperature in this zone is only -8°C and there are fewer than 50 growing
days a year! During the summer, the natural inhabitants of this zone
consist of about 500 plant species and 160 species of vertebrates, including
migratory birds which breed in the arctic and large herds of caribou.
Tundra covers about 24% of Quebec.
Peat bogs and rocky plateaus
covered in lichens and dotted by stands of scrubby black spruce are
indicators that you are in the taiga zone of Quebec. Not as barren
as the tundra, taiga is associated with subarctic regions of the Canadian
Shield and is characterized by a greater number of both plant (600)
and animal (206) species, including many year round inhabitants, such
as tree sparrows. Taiga covers about 20% of Quebec's total area.
The boreal forest
is the most northerly and abundant of Quebec's three forest zones and
straddles the Canadian Shield and upper Lowlands regions of the province.
Dominated by black spruce and carpets of moss, the ecology of this zone
is heavily influenced by fire disturbance regimes, meaning that forest
fires are extremely important in defining the numbers of, and relationships
between, living organisms in this zone. Because of the milder climate,
the diversity of organisms is also higher, with approximately 850 plant
species and 281 vertebrates found here, including the Canada lynx and
American marten. The boreal forest covers 27% of Quebec.
Where the boreal forest overlaps
with the deciduous forest lies the mixed forest zone. As its
name implies, this vegetation zone is a transitional one, whose ecology
is shaped largely by both fire and insect disturbance regimes. The transitional
nature of this zone creates a diversity of habitats which results in
high numbers of plant (1000) and vertebrate (350) species, even in fairly
cool temperatures. Inhabitants include beaver, black bear and moose.
The mixed forest zone covers 11.5% of Quebec and characteristic of the
forests of the Laurentians, Appalachians and eastern lowlands.
The third, and most southern,
forest zone is characterized by deciduous forests (also called
hardwood forests). Because of the climate (mean annual temperature:
7°C), this zone has the highest diversity of species, numbering over
1600 vascular plants and 440 vertebrates. Its relatively longer growing
season of almost 200 days and its fertile soils make this zone the heart
of agricultural activity and, consequently, urbanization in Quebec.
Most of Quebec's population live in this vegetation zone, almost all
of them along the banks of the St. Lawrence river. Wildlife associated
with this zone include the sugar maple, white-tailed deer and the raccoon.
The deciduous zone covers 6.6% of Quebec.
Another large-scale feature
that influences species diversity in Quebec is the St. Lawrence River.
This river drains the Great Lakes, cuts across the southern end of Quebec,
through all three forest ecozones and empties into the Atlantic ocean,
1200 km later. The St. Lawrence watershed is enormous, it drains 40%
of Quebec (680 000 square kilometres) and has a number of aquatic ecosystems
associated with it: fluvial, lake (like Lac St. Pierre and Lac St. Louis),
estuarine and marine. It is no surprise, then, that the ecosystems associated
with the river have the greatest biological diversity in the province.
These ecosystems also have the greatest proportion of human pressure:
98% of Quebec's population lives along the shores of the St. Lawrence
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