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Chapter 34

Chapter 34. The Biosphere: An Introduction to Earth's Diverse Environments. A Mysterious Giant of the Deep Deep-sea submersibles are revealing the diversity of life beneath the ocean Giant squid Hydrothermal vent communities

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Chapter 34

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  1. Chapter 34 The Biosphere: An Introduction to Earth's Diverse Environments

  2. A Mysterious Giant of the Deep • Deep-sea submersibles are revealing the diversity of life beneath the ocean • Giant squid • Hydrothermal vent communities • Animals, such as tube worms, living on energy produced by chemoautotrophic bacteria • Ecology is the scientific study of the interactions of organisms with their environments

  3. Video: Hydrothermal Vent Video: Tubeworms

  4. 34.1 Ecologists study how organisms interact with their environment at several levels • Organism • Individual organisms interacting with the environment • Population • Group of individuals of the same species living in a particular geographic area

  5. Community • All the populations of different species that inhabit a particular area • Ecosystem • All the biotic and abiotic components in a certain area • Ecological research is conducted in the field as well as in the lab and with models

  6. THE BIOSPHERE • 34.2 The biosphere is the total of all of Earth's ecosystems • The biosphere is the global ecosystem • Atmosphere to an altitude of several kilometers • Land down to 3,000 m beneath Earth's surface • Oceans to a depth of several kilometers • The biosphere is self-contained and characterized by patchiness

  7. CONNECTION • 34.3 Environmental problems reveal the limits of the biosphere • No part of the biosphere is untouched by human activities • Current awareness of the biosphere's limits stems from past environmental practices • Rachel Carson warned of the effects of pesticides in 1962

  8. 34.4 Physical and chemical factors influence life in the biosphere • Major abiotic factors determine the biosphere's structure and dynamics • Solar energy • Water • Temperature • Wind • Disturbances such as fire, hurricanes

  9. 34.5 Organisms are adapted to abiotic and biotic factors by natural selection • Species exist in a given place because they evolve there or disperse there • Unique adaptations that fit a particular environment allow organisms to survive there • Example: pronghorns • Organisms vary greatly in their ability to tolerate fluctuations and long-term changes in their environment

  10. 34.6 Regional climate influences the distribution of biological communities • Because of its curvature, Earth receives an uneven distribution of solar energy • The tilt of the Earth's axis causes the seasons of the year • Globe's position relative to the sun changes through the year • The tropics experience the least seasonal variation in solar radiation

  11. LE 34-6a North Pole 60°N Low angle of incoming sunlight 30°N Tropic of Cancer Sunlight strikes most directly 0° (equator) Tropic of Capricorn 30°S Low angle of incoming sunlight 60°S South Pole Atmosphere

  12. LE 34-6b March equinox (equator faces sun directly) June solstice (Northern Hemisphere tilts toward sun) Constant tilt of 23.5° December solstice (Northern Hemisphere tilts away from sun) September equinox

  13. Uneven heating of the Earth sets up patterns of precipitation and prevailing winds • Doldrums are near the equator • Trade winds dominate the tropics • Seasonal climate variation and more moderate temperatures exist in the temperate zones • Prevailing winds are major global air movements

  14. LE 34-6c Descending dry air absorbs moisture Descending dry air absorbs moisture Ascending moist air releases moisture Trade winds Trade winds Doldrums 0° 23.5° 23.5° 30° 30° Temperate zone Tropics Temperate zone

  15. LE 34-6d 60°N 30°N 30°S

  16. Ocean currents have a profound effect on regional climates • Generally modify climate of nearby land • Landforms can also affect local climate • Variations in climate determine the character of the world's biomes

  17. LE 34-6e Fresno 104° 40 miles Death Valley 119° Paso Robles 93° Bakersfield 106° Pacific Ocean Burbank 86° San Bernardino 101° Santa Barbara 75° Key Riverside 91° Los Angeles (Airport) 74° 70s (°F) Santa Ana 84° Palm Springs 104° 80s 90s 100s 110s San Diego 75°

  18. LE 34-6f Wind direction East Pacific Ocean Sierra Nevada Coast Range

  19. AQUATIC BIOMES • 34.7 Oceans occupy most of Earth's surface • Abiotic factors influencing the distribution of aquatic biomes • Light • Distance from shore • Availability of nutrients • Oceanic zones • Intertidal zone: where land meets ocean

  20. Pelagic zone: open ocean • Contains phytoplankton and zooplankton • Benthic zone: seafloor • Photic zone: illuminated regions of the pelagic and benthic zones • Photosynthesis occurs • Aphotic zone: vast, dark region underlying the photic zone • Most extensive part of the biosphere

  21. LE 34-7b Intertidal zone 0 Photic zone 200 m Pelagic zone Continental shelf Benthic zone (seafloor) Aphotic zone 2,500–6,000 m

  22. Continental shelf: submerged part of a continent • Coral reef: found in warm waters above continental shelf • Biologically very diverse • Estuary: area where freshwater stream or river merges with ocean • Among the most productive biomes on Earth

  23. Wetland: area that is transitional between an aquatic and terrestrial ecosystem • Aquatic communities are environmentally threatened Video: Coral Reef Video: Clownfish and Anemone

  24. 34.8 Freshwater biomes include lakes, ponds, rivers, streams, and wetlands • Light has a significant effect on freshwater biomes • All but the most shallow ponds and lakes have photic and aphotic zones • Temperature creates stratification of water • Availability of nutrients and dissolved oxygen influence organic growth • Nitrogen and phosphorus runoff create algal blooms

  25. Rivers and streams support communities quite different from those of lakes and ponds • Freshwater wetlands range from swamps to marshes and bogs • Great ecological and economic value

  26. TERRESTRIAL BIOMES • 34.9 Terrestrial biomes reflect regional variations in climate • Many biomes are named for climatic features and predominant vegetation • Each biome is also characterized by the organisms adapted to that environment • The distribution of biomes depends largely on climate • Within each biome there is local variation

  27. LE 34-9 30°N Tropic of Cancer Equator Tropic of Capricorn 30°S High mountains Tropical forest Temperate grassland Savanna Temperate broadleaf forest Polar ice Coniferous forest Desert Tundra Chaparral

  28. 34.10 Tropical forests cluster near the equator • Rainfall generally determines the type of vegetation in a tropical forest • Tropical rain forests are the most complex of all biomes • Very high diversity • Complex structure • Human impact is of great concern

  29. 34.11 Savannas are grasslands with scattered trees • Savannas are dry and warm • Frequent fires inhibit invasion by trees • Large grazing animals migrate during seasonal droughts

  30. 34.12 Deserts are defined by their dryness • Deserts are the driest terrestrial biomes • Can be hot or cold • Cycles of growth and reproduction are keyed to rainfall • Animals are adapted to drought and extreme temperatures • Desertification is a significant environmental problem

  31. 34.13 Spiny shrubs dominate the chaparral • The chaparral is a region of dense, spiny shrubs with tough, evergreen leaves • In midlatitude coastal areas • Cool, rainy winters and dry, hot summers • Vegetation adapted to periodic fires

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