The Ecological regions of Quebec are regions with specific types of vegetation and climates as defined by the Quebec Ministry of Forests, Wildlife and Parks. Given the size of this huge province, there is wide variation from the temperate deciduous forests of the southwest to the arctic tundra of the extreme north.
Vegetation zones
Quebec covers more than of land between 45° and 62° north, with vegetation that varies greatly from south to north. Most of the natural vegetation is forest, with various species of trees and other plants, and these forests are the habitat for diverse fauna. Energy, precipitation and soil are all important factors in determining what can grow. The climate influences the natural disturbances that affect forests: western Quebec has a drier climate than the east, and experiences more fires. For most species these disturbances are not disasters, and some need them to regenerate.
The climate in Quebec supports rich deciduous forest in the southern regions, and further north become progressively harsher. In the Saint Lawrence Lowlands there are graduations of climate from southwest to northeast. Changes in elevation can have similar effects to changes in latitude, with plants adapted to cooler conditions found higher up. Within a given bioclimatic domain the types of vegetation depend on soil, terrain features such as hilltops, slopes and valley floors, and disturbances such as fires, insect infestations and logging.
The Quebec Ministry of Forests, Wildlife and Parks divides Quebec into three vegetation zones: northern temperate, boreal and Arctic, which correspond to Quebec's major climate subdivisions, and divides these into sub-zones, which in turn are divided into domains and sub-domains. The ministry publishes a map in which these sub-domains are in turn divided into ecological regions and subregions, and then into landscape units.
Geology
All of the bedrock of Quebec north of the foothills of the Laurentian Mountains is the Canadian Shield, one of the oldest and most stable of geological formations in the world, with rocks from 600 million to 4 billion years old. The rocks are hard and mostly acidic. The second largest geological zone is the Appalachians, about 230 million years old, softer and less acidic than the shield. The most fertile part of Quebec is on the rocks of the Saint Lawrence Lowlands, which are at least 250 million years old. They are sedimentary, once the beds of ancient seas.
Most of the rock is covered with surface deposits from a few centimeters or inches thick to over . All forests grow on deposits at least thick. The roots penetrate the deposits and draw water and nutrients from them. All these surface deposits in Quebec date to the last glacial period in North America, when ice completely covered Quebec to a depth of or more. The Laurentide Ice Sheet began to melt in the south about 15,000 years ago, and steadily retreated north, exposing rocks, sand and silt that had been scraped from the rock when the glaciers had moved south. These loose deposits, or glacial till, are the most abundant type of surface deposit in Quebec. The till has often been reworked by the rivers that carried away the water of the melting ice sheet, or by the ancient lakes or seas that flooded inland before the land rebounded from the weight of the ice cap.
The tills drain well due to their stones and abundant sand, but their richness in nutrients depends on their origins. The soil derived from the Shield is mostly acidic, lacking in nutrients such as calcium, stony and with fine particles that are mostly sand. Most of Quebec's coniferous boreal forest grows on the Canadian Shield. The Appalachians form less acidic and more fertile soils, still rocky, but with less sand and more silt. In the Eastern Townships the forests are mostly deciduous, but the forests of the Bas-Saint-Laurent and the Gaspé Peninsula are mostly conifers. Although the soils of the Saint Lawrence Lowlands are very stony they are also very rich in nutrients.
Bioclimatic domains
The Committee on the Map of Ecological Regions of the Quebec Ministry of Forests, Wildlife and Parks defined the current classification of bioclimatic domains in Quebec in 1998. These are regions with similar climate and vegetation. There are ten of these domains. Some of the domains are subdivided into west and east sub-domains due to differences in vegetation caused by differences in precipitation. The domains are:
Northern temperate zone
The northern temperate zone has two sub-zones: deciduous forest and mixed forest.