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Geography of Biomes

Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

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Page 1: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Geography of Biomes

Page 2: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Tundra Biome

• Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra)

• Variable temperatures and rainfall

• Lower elevations and latitudes: willow (Salix spp.), shrub birch (Betula nana), alder (Alnus spp.), sedges, grasses, herbs, and mosses – low arctic tundra

Page 3: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Tundra Biome• High arctic tundra (polar desert) – higher

elevations and latitudes – arctic willow (Salix arctica) and heliotropic flowering plants

• Perennials

• Low biodiversity and biomass

• With the exception of crowberry (Empetrum nigrum), arctic and southern hemisphere alpine tundra have no similar species

Page 4: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Tundra Biome

• Threats:– Resource extraction– Mining– Snowmobiles– Global warming

Arctic willow

crowberry

Page 5: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Chapter 7: Changing Continents and Climates

Tuesday, February 19th

Page 6: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

19th Century Geology

• Law of Superposition – 19th century geologists assumed that strata lower in the stratigraphic exposure were older than the overlying strata

• Law of Uniformitarianism – assumes that processes that weathered, eroded, and deposited rock in the past were the same as those operating today

• These laws used to develop geologic time scale

Page 7: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and
Page 8: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Alfred Wegener

• 1912 Theory of Horizontal Displacement of the Continents – similarities between Atlantic coastlines

• Theory of Continental Drift (1912-1929)– Crust of continents composed of relatively

light rocks. Ocean floors largely composed of dense basalts. Lighter continental rocks could float on viscous mantle of Earth and override oceanic crust

Page 9: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

– Permian glacial deposits in Brazil, South Africa, India, and Australia – indicates that tropical areas once glaciated, so they must have been close to the poles at one time

– Similarities in the shapes of continents, their geology, and fossils suggest closer proximity in the past

– Geodetic measurements of latitude and longitude of Greenland indicated westward movement of the landmass

– Continental Drift led to Plate Tectonics

Alfred Wegener

Page 10: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

• Pangaea

• Gondwanaland – Africa, South America, Australia, Antarctica, and India

• Laurasia – North America, Europe, and Asia

• Pangaea formed 195 mya – began to break up 180 mya with formation of Atlantic Midoceanic Ridge

Alfred Wegener

Page 11: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Figure 7.3

Page 12: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and
Page 13: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Vindication – Alfred Wegener

• Lystrosaurus – Triassic reptile –fossils found in Antarctica, Africa, and India – Antarctica must have been warmer in the past

Page 14: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

• Galaxioidea – freshwater fish family – found in southern South America, South Africa, Australia, and New Zealand – must have been connected in the past

• WWII – sea floor mapping by submarines

Vindication – Alfred Wegener

Page 15: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

• Paleomagnetism – ancient igneous rocks are

little compasses • iron or titanium point to their magnetic north• compare this to current magnetic north to

determine where continents used to lie

Page 16: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Figure 7.6

Page 17: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Glaciation• Radiocarbon dating – based on measuring

the amount of the radioactive isotope carbon 14 found in plant and animal remains

• Greenland ice cores extend 100,000 years• Antarctic ice cores extend 400,000 years• Ice cores provide record of atmospheric

chemistry• 18O isotopes deposited during warmer

times – 16O isotopes deposited during cooler times

Page 18: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Figure 7.7

Page 19: Geography of Biomes. Tundra Biome Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra) Variable temperatures and

Figure 7.9

Relationship between atmospheric temperature and 18O isotopes