The Biosphere Chapter 15

What is the Biosphere? The biosphere is the part of Earth where life exists. All of Earth’s ecosystems, taken together, form the biosphere.

Critical Thinking Activity Connecting Concepts Explain how feedback loops, such as those described in the Gaia hypothesis (pp. 457), might apply to predator- prey relationships. When a prey population increases in size, the predator population has more food to eat. As a result, the predator population increases in size. When the predators become so plentiful that the prey population decreases, the predators have less food to eat. As a result, the predator population decreases in size.

Climate is the Prevailing Weather of a Region. The weather of an area may change from day to day, and even from hour to hour. In contrast, the climate is the long-term pattern of weather conditions in a region. Climate includes factors such as average temperature and precipitation and relative humidity. It also includes seasonal variations such as rainy or dry seasons, cold winters, or hot summers. A microclimate is the climate of a small specific place within a larger area. Microclimates are very important to living things.

Earth’s Three Climate Zones

Critical Thinking Activity Inferring Would areas along the shores of the Great Lakes have warmer summers and colder winters than other inland areas? Explain your reasoning. No, because of the buffering effects of the water, shoreline areas have moderate seasonal temperature changes compared to inland areas.

Biomes A biome is defined by its climate and by the plant and animal communities that live there. A variety of different ecosystems are found within each biome. Earth’s major biomes include: Tropical Grassland Desert Temperate Taiga Tundra

Tropical Rain Forest Biome As little as 1% of the sunlight that strikes the uppermost branches of the canopy make it through to the ground in the tropical rain forest. The soil is very thin and low in nutrients because the large trees absorb available nutrients quickly from the ground. Predict what types of adaptations would be seen in the plant and animal life that dominate a tropical rain forest biome.

Tropical Grassland Biome Tropical grasslands are found in the tropical climate zones of South America, Africa, and Australia. These grasslands are also called savannas. This biome is home to plants and animals that have adapted to the extreme shifts in moisture during the wet and dry seasons.

Temperate Grassland Biome Fast spreading fires are common in temperate grasslands. Many of the plants in temperate grasslands have adapted to fire by producing fire-resistant seeds that require the fire’s heat to start germination. Predict how stopping fires might change a temperate grassland.

Desert Biome Desert biomes receive less than 25cm (10 inches) of precipitation annually. There are four different types of deserts: hot, semiarid, coastal, and cold.

Temperate Deciduous Forest Biome A key feature of temperate biomes is their distinguishable seasons. This biome is characterized by hot summers and cold winters. Deciduous trees have adapted to winter temperatures by dropping their leaves and going dormant during the cold season.

Temperate Rain Forest Biome The temperate rain forest does not receive precipitation evenly spread throughout the year. Coniferous trees, which retain their needles all year, dominate this biome.

Taiga Biome The taiga (TY-guh) is also known as the boreal forest. Winters in the taiga are long and cold, often lasting six months or more.

Tundra Biome Often described as bleak, the tundra is located beyond the taiga in far northern latitudes. Winter here lasts as long as 10 months per year. The ground below the surface is always frozen. This frozen ground is referred to as permafrost.

Chaparral: A Minor Biome Characterized by its hot, dry summers and cool, moist winters. Annual precipitation ranges from 15-40 inches, and occurs mostly during the winter as rain. Dominant plants are small-leaved evergreen shrubs – many of which exhibit similar adaptations to plants found in desert biomes. Many chaparral plants have also adapted to the presence of fire, and some need fire in order for their seeds to germinate. Predict the types of animals that might be well adapted for life in the chaparral.

Polar Ice Caps & Mountains Polar ice caps and mountains are not considered biomes. Polar ice caps have no characteristic plant life. Mountains may exhibit the characteristics of several biomes.

Critical Thinking Activity Connecting Concepts Male birds that migrate the earliest to their summer nesting sites can usually secure the best territories. What limiting factor keeps birds from arriving too early in the taiga? Temperature, because it dictates how much water is available for drinking and also the growth of food that birds rely on.

Interactive Review: Biomes http://www.classzone.com/cz/books/bio_07/resources/htmls/interac tive_review/bio_intrev.html Complete this interactive review using your virtual textbook at home. Concept maps are an excellent way to organize your thoughts and review material!

The Four Zones of the Ocean Intertidal Zone: strip of land between high and low tides; organisms in this zone must tolerate a variety of conditions that result from changing water levels and temperatures. Neritic Zone: extends from the intertidal zone out to the edge of the continental shelf. These are highly productive marine areas. Bathyal Zone: lies between depths of 200 and 2000 meters; has turbid water and fishes that have adapted to living in areas of high pressure. Many burrowing animals thrive here. Abyssal Zone: complete darkness; deep sea vents, only a few species can live here. Chemosynthetic organisms are at the base of the food chain here since sunlight is not available for photosynthetic phytoplankton.

Life in the Neritic Zone Although it represents less than one-tenth of the total ocean area, it contains 40 times more biomass than the rest of the ocean. Much of the biomass is plankton, tiny free-floating organisms that live in the water. Phytoplankton are photosynthetic plankton. These organisms carry out the bulk of the photosynthesis on Earth, and therefore provide most of the oxygen. Seventy percent or more of the oxygen you breathe can be traced back to marine phytoplankton. These organisms also form the base of the oceanic food web. Zooplankton are animal plankton. They are the primary consumers of marine food webs.

Coral Reefs & Kelp Forests Coral reefs are found within the tropical climate zone. A single coral reef may be home to 400 species of corals, along with hundreds of other species of fishes, sponges, and sea urchins. Corals have a mutualistic relationship with algae. The coral provide a home to the algae, and the algae provide nutrients for the coral. Kelp forests exist in cold, nutrient-rich waters. These are areas of high productivity that provide habitat and food sources to many marine species. Kelp is a seaweed that grows from the ocean floor up to the water’s surface.

Critical Thinking Activity Connecting Concepts How might the disappearance of coastal habitats affect an oceanic food web? Because many fish species spend an early stage of their lives in coastal habitats and many marine organisms feed on these and other coastal organisms, the disappearance of these habitats would be devastating to oceanic food webs.

Interactive Review: Marine Ecosystems http://www.classzone.com/cz/books/bio_07/resources/htmls/interactive_review/bio_intrev.html

Estuaries are Dynamic Environments An estuary is a partially enclosed body of water formed where a river flows into an ocean. The distinctive feature of an estuary is the mixture of fresh water from a river and salt water from the ocean. These are highly productive ecosystems, on a level comparable to tropical rain forests and coral reefs. They provide the necessary habitat for a number of endangered and threatened species. The large number of phytoplankton and zooplankton in an estuary support a variety of species. Fish and crustaceans thrive here, as well as birds and other secondary consumers. The removal of estuaries can make coastal areas more vulnerable to flood damage from catastrophic weather events. In some areas of the US, over 80% of the original estuary habitat has been lost to land development.

Critical Thinking Activity Inferring Estuaries occur where rivers flow into the ocean. What conditions in estuaries make them suitable as nurseries for organisms that live out in the open ocean as adults? Estuaries are rich in nutrients, and many feature outer reefs, sandbars, and barrier islands, which offer small organisms shelter.