Boreal shield
The Boreal Shield is the boreal ecoregion of Canada . It is the southern part of the Canadian Shield . It stretches over 3800 kilometers from the eastern tip of Newfoundland to northern Alberta . This landscape interspersed with granite rocks is defined as the overlap of the Canadian shield with the boreal forest of Canada.
The Boreal Shield is also Canada's largest of the 15 ecoregions and covers almost 20% of its land mass (approx. 1,800,000 km²), contains 43% of forest land and provides 22% of Canada's freshwater, excluding groundwater. The ecoregion generates approximately 50 billion Canadian dollars. Hydroelectric power generation contributes CAD 16 billion, while mining and forestry generate around CAD 6 billion each. Forestry provides the raw material for pulp and paper. The Boreal Shield is home to three million people and provides 15% of the jobs that are directly created by natural resources.
The boreal shield ecoregion shows great ecological diversity, including both coastal conditions and strongly continental areas, great differences in the length of the growing season, microclimates, soils and vegetation. Despite this diversity, the character of the boreal shield is relatively uniform over the entire extent of the area.
climate
The area's climate is continental with long, cold winters and short, warm summers. Air masses from Hudson Bay provide annual rainfall of 400 mm in the west to 1000 mm in the east. The average temperatures are −15 ° C in January and 17 ° C in July. Regions in the vicinity of the Great Lakes and the Atlantic are often warmer in winter and cooler in summer due to the balancing effect of the large bodies of water. On average there are 60 to 100 frost-free days a year, with some areas having fewer than 40 frost-free days. This means that the ecoregion is no longer climatically suitable for arable farming, as modern cereal cultivation requires 100 frost-free days a year. However, the soils of the ecoregion are shallow and not very fertile anyway.
Floors
The bedrock of the boreal shield is banded gneiss , one of the oldest rock formations on earth, formed from granite. During the last Ice Age, which ended 10,000 years ago, the shield was repeatedly abraded deep into the rock by advancing glaciers. The loosened sediment was carried away by meltwater, so that today only shallow, very acidic and nutrient-poor soils can be found. The high bedrock also ensures that the watering is unfavorable for plants. Wetlands occupy large areas. As a result of lack of oxygen and constant moisture, their organic soils are a poor plant location.
Water balance
The boreal shield is famous for its lakes and rocky banks. The action of ice age glaciers created thousands of cut-off depressions, holes and furrows that are now filled with water. The ancient crystalline bedrock with its faults , dykes , fissures and fractures shapes the flow dynamics of the water in such a way that hydrologists describe the water regime as chaotic.
After the last ice age, the area began to be colonized by humans, who used the extensive network of rivers and lakes as a transport route and source of food. In addition to fishing, trapping and hunting were practiced because the waters also attract other mammals. Nowadays, people primarily use the area's waters to generate electricity and for recreation.
To the east of the Boreal Shield, marine food webs begin on the rocky shores of the Gulf of St. Lawrence and Newfoundland, which are also breeding grounds for many seabirds.
flora
While agriculture in the Boreal Shield faces severe restrictions, and regular wildfires are also a limiting factor for vegetation, coniferous forests thrive there and cover 85% of the ecoregion. The forests are characterized by a few very adaptable tree species: black spruce , white spruce , Pinus banksiana ( "jack pine" ) and balsam fir . Black spruce is the most common and is a source of high quality pulp for Canada's growing paper industry.
The proportion of deciduous deciduous trees increases in the more southern parts of the shield. In addition to the conifers, paper birches , the American Populus tremuloides and the western balsam poplar are also represented. In the southeast of the area there are also species that are common in temperate climates, such as yellow birch , sugar maple , black ash and the occidental tree of life .
In the entire ecoregion, these forests are mixed with countless raised bogs , fens , marshes and other wetlands. With 20% of the area, these ecosystems are the most biodiverse and productive in the Boreal Shield.
fauna
Every spring the numerous bodies of water attract hundreds of thousands of ducks , loons , geese and swans . They either come to breed or, en route to their breeding grounds further north, to rest and to eat. The most numerous species represented waterfowl that spend the summer in the boreal shield are Bufflehead ducks , dark ducks , wood ducks , Ring-necked ducks , mallards , North American wigeon , blue-winged duck , shoveler and Canada geese . Boreal Owl , Great Horned Owl , evening grosbeak , Blue Jays and White-throated Sparrow are also typical summer guests in the area.
Characteristic mammals, key species of the Boreal Shield, are reindeer , white-tailed deer , elk , American black bear , wolf , lynx , snowshoe hare , fishing marten , real marten and skunks . The numerous wetlands, ponds, lakes and rivers are important habitats for beavers , muskrats and American mink .
In the arctic coastal area there are folding hats , blue whales , fin whales , duck whales , sperm whales , killer whales and pilot whales . The endangered bowhead and humpback whales can also be encountered here. Inland, the American char , herring vendace , pikeperch ( Sander vitreus ), brook trout and European pike are among the most common species of the countless lakes and rivers in the ecoregion.
source
- Minister of Public Works and Government Services Canada, 2000: Ecological Assessment of the Boreal Shield Ecozone, ISBN 0-662-28679-0