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The Biosphere

Biology Ch. 15. The Biosphere. 15.1 Life in the Earth System. The biosphere is the part of the Earth where life exists. The biota is the collection of living things that live in the biosphere. There are 3 additional Earth systems: Hydrosphere: water, ice, and water vapor

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The Biosphere

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  1. Biology Ch. 15 The Biosphere

  2. 15.1 Life in the Earth System • The biosphere is the part of the Earth where life exists. • The biota is the collection of living things that live in the biosphere. • There are 3 additional Earth systems: • Hydrosphere: water, ice, and water vapor • Atmosphere: air blanketing Earth’s solid and liquid surface • Geosphere: the features of Earth’s surface (continents, rocks, sea floor) and everything below the surface. • All 4 systems interact and a change in one sphere can affect others.

  3. The Gaia hypothesis explains how biotic and abiotic factors interact in the biosphere. • According to this hypothesis, the Earth itself is a kind of living organism. • The atmosphere, geosphere, and hydrosphere are cooperating systems that yield the biosphere. • The Gaia hypothesis recognizes the extensive connections and feedback loops between living and nonliving parts.

  4. 15.2 Climate • Climate is the long term pattern of weather conditions in a region. • Includes average temperature, precipitation, relative humidity, and seasonal variations. • The key factors that shape an area’s climate include: • Temperature, sunlight, water, and wind • Temperature and moisture play a large role in the shaping of ecosystems • A microclimate is the climate of a small specific place within a larger area.

  5. Earth has 3 main climate zones • Scientists use average temperature and precipitation levels to categorize a region’s climate. • The 3 zones: • Polar: far northern and southern regions of Earth • Tropical: surrounds the equator • Temperate: wide area in between the polar and tropical zones

  6. Influence of Sunlight • The amount of solar energy received from the sun determines an area’s climate. • The sun’s rays are most intense and hottest on the portion of the planet that sunlight strikes most directly. • Earth’s surface is heated unevenly due to it’s curved shape. • The area of the Earth that receives the most direct radiation all year is the region around the equator (tropical climate zone)

  7. Near the poles, the sun’s rays strike the Earth at a low angle. • The tilt of the Earth’s axis also plays a role in seasonal change. • During Earth’s revolution, different regions of the planet receive higher and lower amounts of sunlight. • The hemisphere that is tilted toward the sun is experiencing summer.

  8. Air and Water Movement • Warm air and water are less dense than cooler air and water. • Warm air and water rise because they are less dense and cooler air and water sink because they are more dense. • Warm air near the tropics rises. • The cooler sinking air from the poles moves in to take it’s place • As warm air rises, it cools.

  9. Since cold air holds less moisture than warm air, there is a large amount of precipitation. • Warm temperatures and large amounts of precipitation defines the tropical rain forests found near the equator. • The movement of air leads to the movement of water forming currents. • Currents are also generated by the rotation of the Earth, water temperatures, and salinity levels.

  10. Landmasses • Areas closer to bodies of water have a different climate from areas that are farther inland because land heats and cools more quickly than water. • Coastal areas tend to have smaller changes in temperature. • Water evaporates from open bodies faster than it does from soil or by transpiration. • Coastal regions have higher humidity and receive more precipitation than inland areas.

  11. Mountains also have an effect on climate. • As warm, moist air rises up a mountain slope, it will cool which results in precipitation on that side of the mountain. • The air that descends the other side of the mountain is drier and cooler. • This produces a rain shadow which has less precipitation.

  12. 15.3 Biomes • Tropical Rain Forest • Warm temperatures and abundant precipitation throughout most of the year. • Lush thick forests that completely shade the forest floor. • The limiting factor is sunlight • The uppermost branches of the trees of the forest make up the canopy. • Soil is very thin and low in nutrients. • Most organisms found in this biome live in the upper branches of the canopy. • Animals use loud vocalizations to defend territory and attract mates.

  13. A grassland is an area where the primary plant life is grass. • Tropical grasslands • Savannas • Covered with grass plants that may be meters tall • Scattered trees or shrubs that do not grow very thick or flush • Limiting factor is rainfall • Very little precipitation (less than 10cm a month) • Lakes, rivers, streams, and wetlands are replenished during the rainy season. • Plants and animals have to adapt to extreme shifts in moisture.

  14. Temperate Grasslands • Receive 50 to 90 cm of precipitation per year. • Most of the precipitation is rain in the late spring and early summer. • Summers may be warm or quite hot. • Fast spreading fires are common. • Some plants have adapted to fire by producing fire resistant seeds. • The fire’s heat starts germination • Many animals live below ground

  15. Deserts • Receive less than 25 cm of precipitation per year. • Very dry or arid climate • In hot deserts, daily temperatures easily top 100° but at night temperatures drop significantly due to lack of moisture. • During winter, temperature may drop to as low as 32°. • Semiarid deserts also have long dry summers and low amounts of rain in the winter. • Temperatures in semiarid deserts are cooler than hot deserts.

  16. Costal deserts have cool winters and long warm summers. • Temperatures range from 25° in the winter to 95° in the summer. • In cold deserts, precipitation falls evenly throughout the year and often occurs as snow in the winter. • Summer daily temperatures range from 50° to 75° and winter temperatures can drop below freezing.

  17. Plants and animals use a variety of strategies to survive a deserts heat and lack of moisture • Reduced surface area of a cactus spines helps retain more moisture by reducing transpiration • Many plants have the ability to conserve or store water. • Some plants have long roots that extend down to the water table • Plants have heat and drought resistant seeds. • Many animals are nocturnal

  18. A key feature of temperate biomes is their distinguishable seasons. • The growing season occurs during warmer temperatures of mid-spring to mid-fall and depend on the availability of water. • Temperate deciduous forests • Receive about 75 to 150 centimeters of precipitation over the year as rain or snow. • Hot summers and cold winters • Deciduous trees have adapted to winter temperatures by dropping their leaves and going dormant during the cold season. • Vegetation includes oaks, beeches, maples, shrubs, lichens, and mosses

  19. Temperate rain forests • Do not receive precipitation evenly throughout the year. • One long wet season and a relatively dry summer. • During the dry summer, fog and low lying clouds provide the moisture. • Average annual precipitation exceeds 250 cm. • Evergreen conifers such as spruces, firs, and redwoods • Coniferous trees retain their needles all year. • Mosses, lichens, and ferns are found on the forest floor.

  20. Taiga • Boreal forest located in cooler climates • Winters are long and cold often lasting 6 months or more. • Average winter temperature is below freezing. • Summers are short (2 to 3 months) but may be quite humid and warm • Precipitation is 30 to 85 cm annually. • Coniferous forests are dominant. • Mammals have heavy fur coats

  21. Tundra • Located beyond the taiga in far northern latitudes • Winter lasts as long as 10 months. • Average winter temperature is below freezing. • Ground below the surface is always frozen and is known as permafrost. • Summers last 6 to 10 weeks • Less than 13 cm of precipitation annually. • The permafrost holds the moisture making less available to plants. • Very barren with the only plants being mosses, tiny low lying plants, and a few shrubs.

  22. Minor Biomes • Chaparrals • Also called Mediterranean shrublands • Characterized by hot dry summers and cool moist winters • Temperatures range from 50° to 104° • Annual precipitation ranges from 38 to 102 cm with most occurring during the winter as rain.

  23. Dominant plants are small evergreen shrubs. • Because of the hot climate plants have many of the same adaptations as those found in deserts. • Many plants have shallow root systems and thick cuticles. • Oils released by some plants are flammable and promote fires. • Many of the plants need the fires in order for seeds to germinate.

  24. Polar ice caps and mountains are not considered biomes. • Polar ice caps have no soil and do not have a specific plant community. • In mountains the climate and the animal and plant communities change depending on elevation.

  25. Polar ice caps • Occur around the poles • Parts of Greenland and permanently frozen parts of the Arctic Ocean and surrounding islands in the northern hemisphere. • Glacier covered surface of Antarctica in the southern hemisphere. • Ice and snow cover the surface year round. • Very few plants or fungi are able to survive. The only plants are mosses and lichens. • Most animals depend on the sea for their food. • Polar bears (north) and penguins (south) are able to survive due to layers of fat and living in very close proximity to each other.

  26. Mountains • Rich with life • Many different communities of species at different mountain elevations. • As you move up a mountain, the different communities are similar to the biomes found at different latitudes. • Life zones found on mountains are similar across biomes but the species of plants and animals differ because of different abiotic factors.

  27. 15.4 Marine Ecosystems • Ocean Zones • Water of the open ocean (pelagic) and the ocean floor (benthic) • The photic zone is the portion of the ocean that receives sunlight. The aphotic zone receives no sunlight. • Distance from shore is another way to divide the ocean into zones. • Intertidal: region between low and high tide; organisms in this zone must tolerate a variety of conditions. • Neritic: extends from the intertidal zone to the edge of the continental shelf • Bathyl: extends from the edge of the neritic zone to the base of the continental shelf • Abyssal: Deepest part of the ocean in complete darkness; low number of species; chemosynthetic organisms.

  28. Life in the Neritic Zone • Contains the majority of the biomass of the ocean • Most of the biomass consists of plankton (free floating) • Zooplankton are animal like plankton • Phytoplankton are photosynthetic (algae) • Phytoplankton such as blue-green algae are critical to life on Earth because they carry out the majority of photosynthesis (70%) • Phytoplankton also forms the base of the oceanic food web.

  29. Unique Habitats of Coastal Waters • Coral reefs • Found within the tropical climate zones • Water remains warm all year • Home to hundreds of species forming a very large biomass • Corals are animals that have a mutualistic relationship with algae. • The corals provide a home and the algae provide nutrients • Made mostly of coral skeletal material • Very delicate and are easily affected by changes in water temperature.

  30. Kelp Forests • Exist in cold nutrient rich waters • Kelp is a type of seaweed • Kelp can grow to heights over 100 ft. • Areas of high productivity providing a habitat and food sources

  31. 15.5 Estuaries and Freshwater Ecosystems • An estuary is a partially enclosed body of water formed where a river flows into the ocean. • The Chesapeake Bay • An estuary is a mixture of fresh and salt water • The rivers carry nutrients and tidal movements bring organic matter and marine species from the ocean. • An estuary contains a large number of species.

  32. Estuaries • Highly productive • Photosynthetic organisms thrive and form the basis of the aquatic food web. • Thriving detritivore (decomposer) communities that return nutrients back to the ecosystem. • Provide a necessary habitat for a number of threatened and endangered species.

  33. Estuary Characteristics • Large number of phytoplankton and zooplankton that support a variety of species. • Fish, crustaceans, birds, and humans • 75% of the fish we eat comes from estuaries • Estuaries provide a protected refuge for many species • Reefs and barrier islands protect species from waves and storms and provide a site where many species lay eggs and their young mature. • Estuaries are sometimes called the nurseries of the sea.

  34. Estuaries are a key part of the migration paths of many bird species. • Birds rely on estuaries as a refuge from cold weather during certain parts of the year. • Changing conditions present challenges for species • To withstand changing salinities, some organisms have glands that remove excess salt.

  35. Threats to Estuary Ecosystems • Land development and other human activities • Removal of estuaries make coastal areas more vulnerable to flood damage • Excess nutrients increase algal bloom growth which take up nutrients and block out sunlight.

  36. Freshwater Ecosystems • Rivers, streams, lakes, and ponds originate from watersheds • A watershed is a region of land that drains into a body of water. • Along a river changes can be observed in: • Shoreline ecosystems • Speed of flow • Composition of the river bottom • Water levels due to melting of snow, dams, and draining water for irrigation and drinking water.

  37. Wetlands have very little water flowing through them. • A wetland is an area of land that is saturated by ground or surface water • Bogs, marshes, and swamps are types of wetlands that are identified by plant communities (cattails, duckweed, and sedges) • Wetlands are among the most productive ecosystems on Earth • They provide a home for a large number of species • They also help maintain a clean water supply by filtering water.

  38. Adaptations of Freshwater Organisms • Factors that determine the types of freshwater organisms • Temperature • Oxygen levels • pH • Water flow rate • Organisms that live in freshwater environments have adaptations that are well suited to water conditions.

  39. Zones of freshwater ponds and lakes • Littoral • located between high and low water marks on the shoreline • Water is well-lit, warm, and shallow • Diverse set of organisms • Limnetic • Open water located farther out from shore • Abundance of plankton • Benthic • Bottom zone where there is less sunlight • Decomposers such as bacteria

  40. Water temperature in a lake is normally stratified which means that there are different layers with different temperatures. • The boundary between layers is called a thermocline • All of the water in a lake turns over periodically due to changes in temperature. • Water is most dense at 4˚C (39˚F) • When water reaches this temperature, it will sink. This happens during autumn and spring. • During these seasons, deep water flows upward and replaces the sinking surface water in a process called upwelling. • Upwelling brings nutrients to the surface

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