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 predatorprey 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.