Chapter 47: The Biosphere

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Chapter 47 The Biosphere

• Section 1
• Earth A Living Planet

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Earth A Living Planet

• Ecology is the study of the interactions of
  organisms with one another and with their
  physical surroundings
• Scientists who study ecology are called
  ecologists
• Earth is a single living system, also known as a
  biosphere, or living globe

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A fast-moving stream in Gatlinburg, TN is an
example of how organisms interact with one
another and with their physical surroundings. The
spray from the stream made it possible for mosses
to grow on the surfaces of nearby boulders
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Earth A Living Planet

• The biosphere is that part of the Earth in which
  life exists
• Includes all areas of land, air, and water on the
  planet, as well as all the life that populates
  these areas
• Extends from about 8km above Earths surface to
  as far as 8km below the surface of the ocean
• Organisms are not distributed evenly throughout
  the biosphere

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Ecosystems

• Because the biosphere is large, ecologists like
  to work with smaller units called ecosystems
• An ecosystem consists of a given areas physical
  features (abiotic factors) and living organisms
  (biotic factors)
• Abiotic factors water, sunlight, soil type,
  rocks, temperature, humidity, elevation, and
  rainfall
• Biotic factors fish, frogs, insects, snails,
  worms, trees, ferns, lilies
• The organisms living together in an ecosystem are
  often referred to as a community

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Ecological Succession

• Ecosystems change over time because every
  organism affects environmental conditions around
  it
• In the process of ecological succession an
  existing community of organisms is replaced by a
  different community over periods of time ranging
  from a few decades to thousands of years

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Ecological Succession

• Sometimes succession occurs in places where no
  living community existed before
• When a new volcanic island arises from the sea,
  its newly cooled lava contains no life
• Organisms that colonize such areas are called
  pioneer species
• Succession can dramatically transform an
  ecosystem
• Over time, a lake or pond may fill up with silt
  and organic matter, turning first into a marsh
  and then into dry land

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Ecological Succession

• As physical factors change, living communities
  also change
• Succession can also occur in places where natural
  disasters or human activities wipe out existing
  communities
• In much of the United States, for example,
  abandoned farmland is colonized first by grasses,
  then by other weeds, and later by shrubs and
  small trees
• Succession often leads to a fairly stable
  collection of organisms called a climax community

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Ecological Succession

• An areas climax community is due partly to
  chance
• An ecosystem may eventually return to the way it
  was after trees are cut down, land is dug up for
  mining, or any other kind of environmental damage
  occurs
• But, it is also possible that succession will
  take a different path and things will never be
  the same again

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Chapter 47 The Biosphere

• Section 2
• Land Biomes

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Land Biomes

• A biome is an environment that has a
  characteristic climax community
• The Earth is made up of two main types of biomes
  land biomes and aquatic biomes
• Most land biomes are named for their climax
  community, or the dominant type of plant life

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Tundra

• Climate cold, long winters and cool, short
  summers, with little precipitation
• Yearly precipitation 10 inches
• Covers 1/5 of Earths land surface
• Annual precipitation is low
• H2O is unavailable most of the year
• Ground is permanently frozen
• Grasses, sedges, dwarf willows, mosses
• Foxes, reindeer, owls, caribou

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Taiga

• Climate cool, short summers and cold, long
  winters
• Yearly precipitation 8 24 inches
• Ideal conditions for needle-leaved trees
• One of the largest biomes on Earth
• Marshes, lakes, and ponds are common
• Pine trees, fir trees, birch trees
• Elk, moose, deer, wolves, bears, wolverines

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Temperate Deciduous Forests

• Climate warms summers and cool to cold winters
• Yearly precipitation 30 100 inches
• Trees shed their leaves in the fall
• Precipitation is distributed evenly throughout
  the year
• Contains humus ( a layer of decaying leaves and
  twigs)
• Deer, bears, beavers, raccoons, moose
• Oak trees, hickory trees, beech trees, shrubs

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Grasslands

• Climate dry, hot summers and cold winters
• Yearly precipitation 4 24 inches
• Agricultural land
• Populated by herds of grazing mammals
• Impala, wildebeests, elephants
• Grasses, trees, shrubs, crops

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Tropical Rain Forests

• Climate warm and moist, with little variation
  in either rainfall or temperature
• Yearly precipitation 100 inches
• Most diverse biome
• ½ of Earths species are here
• Most will be gone within 40 years
• Leads to the extinction of large numbers of
  species
• Lush plants, trees
• Butterflies, monkeys, insects

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Deserts

• Climate very dry, often hot
• Yearly precipitation 8 inches
• Organisms have features that allows them to
  conserve water
• Vegetation is sparse
• Less than 5 of North America is desert
• Creosote brushes, cacti
• Roadrunners, kangaroo rats, kit foxes

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Chapter 47 The Biosphere

• Section 3
• Aquatic Biomes

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Aquatic Biomes

• Water ecosystems
• Includes freshwater, marine, and estuaries
• These biomes support more organisms than do the
  land biomes
• Some of the abiotic factors that affect the kinds
  of organisms found in the aquatic biomes are
  light intensity, amounts of oxygen and carbon
  dioxide dissolved in the water, and the
  availability of organic and inorganic nutrients

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Freshwater Biomes

• Rivers, streams, and lakes are considered the
  freshwater biomes of the Earth
• They provide much of our drinking water and are
  an important source of food
• Tiny floating plants and animals drift and swim
  through the water
• These organisms are eaten by fish and amphibians,
  which also eat the vegetation and insects that
  fall into the water from overhanging trees

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Freshwater Biomes

• Contains insects, fish, amphibians, reptiles, and
  mammals
• Unfortunately, people all over the world are
  using rivers and lakes as dumping grounds for
  wastes
• The results of this carelessness are beginning to
  catch up with us

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In swift-moving rivers, most organisms live in
the shallows, where algae and mosses cling to the
surfaces of rocks.
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Marine Biomes

• The vast habitats of the ocean, or the marine
  biomes, cover most of the surface of Earth
• Photosynthesis can only take place in the
  uppermost region of a marine biome
• This region is called the photic zone
• May be as shallow as 30m or as deep as 200m
• Phytoplankton and algae grow here

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Marine Biomes

• Oceanographers have divided marine biomes into
  distinct zones based on their depth and distance
  from the shore
• Each of these zones contains organisms that are
  adapted to the conditions there

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Intertidal Zone

• Most difficult zone for organisms to live in
• Must tolerate radical changes in their
  surroundings
• Once or twice a day they are submerged in ocean
  water
• The remainder of the time they are exposed to air
  and sunlight
• Organisms here have adapted in some way to the
  pounding and crashing of waves
• Some organisms burrow into the sand to keep from
  being washed out to sea
• Others attach themselves to rocks

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The intertidal zone is characterized by organisms
such as barnacles and starfish.
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Neritic Zone

• Extends from the low-tide line to the edge of the
  open sea
• Large seaweed are abundant here because this part
  of the ocean is the photic zone
• In shallow areas of tropical waters, meadows of
  turtle grass provide food for fish,
  invertebrates, and turtles
• Along the ocean floor, lobsters and crabs crawl
  while flounder and rays swim above them

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The neritic zone provides a home to brilliantly
colored coral-reef fishes.
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Open-Sea Zone

• Phytoplankton are responsible for 80-90 of the
  Earths photosynthetic activity
• Phytoplankton are eaten by larger animals
• Thus the chain of life in the sea begins with
  these tiny organisms
• Swimming rapidly through the open-sea zone are
  fish of all shapes and sizes and mammals such as
  dolphins and whales

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Open-Sea Zone

• Because nutrients are scarce in most of the open
  sea, the growth of phytoplankton is relatively
  slow
• This limits the number of animals that can live
  there
• Closer to the shore, however, nutrients are more
  abundant, and countless fish swim there to feed
  and reproduce
• Unfortunately, these rich fishing areas are much
  more susceptible to pollution than is the open sea

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Deep-Sea Zone

• Area of high pressure, cold temperature, and
  total darkness
• This area is home to some of Earths strangest
  creatures
• Here, zooplankton wait for night in order to
  migrate to the oceans surface and feed on
  phytoplankton
• Herds of bottom dwellers crawl along on the ocean
  floor

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The deep-sea zone is home to some of the Earths
most bizarre creatures. The tube worms belong to
an ecological community whose ultimate source of
energy is chemicals from volcanic vents.
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Estuaries

• Estuaries are found at the boundary between fresh
  water and salt water
• Salt marshes, mangrove swamps, lagoons, and the
  mouths of rivers that empty into the ocean are
  examples of estuaries
• Estuaries support a variety of life forms
• Because estuaries are usually shallow, sunlight
  is able to penetrate the water completely

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Estuaries

• Photosynthesis occurs at all levels, making
  estuaries a suitable environment for aquatic
  plants
• The abundance of such plants, in turn, supports
  many types of fish, shrimp, and crabs
• In fact, many fish and invertebrates spawn,
  hatch, and nurse their young in estuaries
• As the young mature, they head for open sea, then
  return to the estuaries to reproduce
• Several species of birds use estuaries for
  nesting, feeding, and resting

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Estuaries are areas where fresh water and salt
water meet. This salt marsh in Long Island, New
York and the mangrove swamp in Florida are
examples of estuaries.
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Chapter 47 The Biosphere

• Section 4
• Energy and Nutrients Building the Web of Life

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Energy and Nutrients Building the Web of Life

• One of the most important factors in any
  ecosystem is the flow of energy through the
  ecosystem
• Approximately ½ of the energy plants absorb from
  the sun is used immediately
• The rest is stored in plant tissues in the form
  of carbohydrates
• Animals that eat the plants obtain this energy

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Energy and Nutrients Building the Web of Life

• Energy cannot be recycled, or used again
• Thus energy in an ecosystem is referred to as a
  flow rather than a cycle
• Nutrients are generally recycled through an
  ecosystem
• When an animal dies, its matter does not
  disappear
• Rather, it decomposes and eventually gets used by
  another organism

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Organisms are classified as producers, consumers,
or decomposers, depending on how they get their
food. Because spruce budworms feed directly on
the jack pine, which is a producer, they are
called primary consumers. Robins, which feed on
worms, are called secondary consumers.
Decomposers, such as mushrooms, get their food
from the remains of dead organisms.
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The Flow of Energy

• The sun is the ultimate source of energy for all
  living things
• Because photosynthetic organisms are able to make
  their own food from inorganic substances, they
  are called producers
• Animals, on the other hand, are consumers
• Consumers get their energy either directly or
  indirectly from producers

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The Flow of Energy

• Consumers that feed directly on producers are
  called primary consumers
• Herbivores
• Consumers that feed on primary consumers are
  called secondary consumers
• Carnivores
• Energy flows through an ecosystem from the sun to
  producers and then to consumers

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The Flow of Energy

• When plants and animals in an ecosystem die,
  their remains do not build up because of the
  presence of decomposers
• Decomposers are organisms that obtain their
  energy from nonliving organic matter
• Each step in this series of organisms eating
  other organisms is called a trophic, or feeding,
  level

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The Flow of Energy

• At each higher trophic level, less and less of
  the energy originally captured by the producers
  is available
• Approximately 10 of the energy at one trophic
  level can be used by animals at the next trophic
  level
• At each successive trophic level, less energy is
  available to an organism

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Ecological Pyramids

• Ecologists use ecological pyramids to represent
  the energy relationships among trophic levels
• There are three types of ecological pyramids
• Pyramid of energy
• Pyramid of biomass
• Pyramid of numbers

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Pyramid of Energy

• A pyramid of energy shows the total amount of
  incoming energy at each successive level

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Pyramid of Biomass

• The trophic levels of an ecosystem can also be
  represented by a pyramid of biomass, which shows
  the total mass of living tissue at each level

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Pyramid of Numbers

• Relationships among trophic levels may also be
  represented by a pyramid of numbers
• A pyramid of numbers illustrates the total number
  of organisms at each level

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Biogeochemical Cycles

• Although energy moves in a one-way direction
  through an ecosystem, nutrients are recycled
• All organisms require certain essential nutrients
  in order to grow
• As members of each trophic level eat members of
  the level beneath them, they acquire the complex
  organic molecules and elements they need in
  addition to energy
• Nutrients move through the biosphere in a series
  of physical and biological processes called
  biogeochemical, or nutrient, cycles

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The Water Cycle

• The movement of water from the atmosphere to the
  Earth and back to the atmosphere is called the
  water cycle
• The water cycle consists of an alternation of
  evaporation and condensation
• Water molecules enter the air by evaporation from
  the ocean and other bodies of water
• In the air, water molecules condense and then
  return to the Earth in the form of precipitation

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The Water Cycle

• On land, most of the rainwater runs along the
  surface of the ground until it enters a river or
  stream that carries it to a larger body of water
• Some water sinks into the ground and is called
  groundwater
• The upper surface of groundwater is known as the
  water table

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The Water Cycle
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The Nitrogen Cycle

• All organisms require nitrogen to build proteins
• The movement of nitrogen through the biosphere is
  called the nitrogen cycle
• However, most of the nitrogen cannot be directly
  used by living things
• It must be converted into other forms

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The Nitrogen Cycle

• Certain bacteria that live on roots of plants
  change free nitrogen in the atmosphere into
  nitrogen compounds that can be used by living
  things
• Nitrogen fixation
• Once the nitrogen compounds are available, plants
  use them to make plant proteins
• Animals then eat the plants and use the proteins
  to make animal proteins
• When the plants and animals die, the nitrogen
  compounds return to the soil

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The Nitrogen Cycle

• Eventually other bacteria in the soil break down
  these nitrogen compounds into free nitrogen in a
  process called denitrification
• These bacteria are called denitrifying bacteria
• Through the process of denitrification, free
  nitrogen is returned to the atmosphere

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The Nitrogen Cycle
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The Carbon and Oxygen Cycles

• The process by which carbon is moved through the
  environment is called the carbon cycle
• During photosynthesis, green plants and algae use
  carbon dioxide from the atmosphere to form
  glucose
• Consumers and decomposers use glucose in
  respiration, during which they produce carbon
  dioxide
• Carbon dioxide is then released into the
  atmosphere, completing the carbon cycle

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The Carbon and Oxygen Cycles

• The movement of oxygen through the environment is
  called the oxygen cycle
• During photosynthesis, water molecules are split,
  releasing oxygen into the atmosphere
• The oxygen is used by most organisms for
  respiration
• During respiration, water is released
• The water is absorbed by plants, and the cycle
  begins again

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The Carbon Cycle
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The Oxygen Cycle
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Nutrient Limitation

• The rate at which producers can capture energy
  and use it to produce living tissue is controlled
  be several factors, one of which is the amount of
  available nutrients
• If a nutrient is in short supply thus limiting
  an organisms growth it is called a limiting
  factor

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Feeding Relationships

• The simplest feeding relationship is a food chain
  
• In one food chain, a big fish eats little fish
  that eat tiny fish that eat plankton
• Nature is almost never that simple
• Instead of using a food chain, which only shows
  one feeding level, ecologists use food webs
• Food webs have many crisscrossing strands

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