Geography Boreal Shield Ecozone (CEC)

1 geography

1.1 formation
1.2 climate
1.3 landforms
1.4 vegetation
1.5 wildlife
1.6 changing conditions

geography
formation

canadian shield rock forms nucleus of north american continent. other geological structures assumed positions around or on top of shield millions of years after formed. rocky mountains relative newcomers on geological stage. shield rocks formed on billion years earlier, during first chapter of planet s history known precambrian era.

what once may have been towering mountain chain today great rolling plain of ancient bedrock. during late precambrian era, fierce convulsions in earth’s crust resulted in warped, collapsed shield. foundation of of ecozone metamorphic gneiss, highly banded rock formed intense pressure , heat. many of minerals contribute shield’s economy may have formed during these geologically turbulent times.

during last ice age, ended 10 000 years ago, advance of glaciers continuously plucked , scoured boreal shield, forming striations in bedrock , carrying large boulders many kilometers. in retreat, massive glaciers enveloped of landscape great amounts of glacial deposits including gravel, sand, shale, , numerous sediments. vast majority of inadequately drained depressions left behind, natural faults in bedrock, form millions of lakes, ponds , wetlands give ecozone distinctive character.

climate

the regional climate has long, cold winters , short, warm summers, conditions moderated in coastal regions. mean annual temperature ranges -4 °c in northern saskatchewan 5.5 °c in newfoundland. precipitation increases west east. permafrost widespread.

landforms

the ecozone characterized broadly rolling uplands , lowlands precambrian granitic bedrock outcrops. there numerous lakes , rivers, accounting 22% of canada’s freshwater surface area. types of soil vary muskeg glacial-deposited sands.

vegetation

the region forested white , black spruce, balsam fir , jack pine. deciduous trees more common in south, white birch, trembling aspen , balsam poplar. there yellow birch , sugar maple east. in areas of muskeg there stands of black spruce or tamarack. there frequent forest fires.

wildlife

being largely wild , remote, ecozone rich in wildlife, including woodland caribou, moose, wolf, black bear, raccoon, marten, fisher, striped skunk, lynx, bobcat , eastern chipmunk. common birds include boreal owl, great horned owl, blue jay, white-throated sparrow , evening grosbeak. lakes contain brook char, lake trout, northern pike, perch, , walleye.

off northern , eastern coasts, aquatic mammals include grey seal, harp seal, hooded seal, ringed seal, sperm whale, orca, atlantic pilot whale, fin whale, blue whale, northern right whale, bowhead whale, , humpback whale.

changing conditions

fire suppression, insect control, clear-cutting , single-species tree farming widespread in accessible areas. these practices may, on long term, reduce diversity of both plant , animal species , increase forest’s vulnerability disease.

many shield lakes , soils extremely sensitive changes in ph. acid rain local sources , long-range transport of airborne pollutants has taken ominous toll. may weakening general vigour , growth rate of trees, of aquatic species, in sensitive areas.