1. Introduction

2. Geology of Quebec

3. Vegetation zones of Quebec

 

1. Introduction

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 of Quebec.

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.

 

2. The 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 them.

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 and streams.

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 of Quebec.

 

3. The 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 Deciduous forest.

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 River.

 

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