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U1 S2 L3

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U1 S2 L3 & L4 Energy Flow in Ecosystems – PowerPoint PPT presentation

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Title: U1 S2 L3


1
U1 S2 L3 L4Energy Flow in Ecosystems
2
What Affects the amount of Energy Reaching
Ecosystems?
  • Albedo
  • Other Environmental Factors

3
The flow of energy from the sun
4
The Albedo Effect
Albedo is a measure of the amount of light
reflected from an object. Albedo is normally
expressed as a decimal value representing the
percentage of light reflected. For example,
clouds have an average albedo about 0.27 so about
27 of the suns energy is normally reflected by
clouds back to space. On a clear day, more
light would be able to penetrate to the Earths
surface. What has a greater albedo effect, snow
covered glaciers or the canopy of the
rainforest? To stay warm in the winter what
color would you wear? Why?
Albedo affects the amount of energy from the sun
available for an ecosystem. The Higher the albedo
the less the energy available to an ecosystem!
5
Sample Albedo Values
6
Energy Budget
  • Defined as the total Energy available to
    organisms in an ecosystem.
  • What determines the energy budget?
  • An ecosystem's energy budget depends on primary
    productivity
  • Primary Productivity
  • The total amount of food created by primary
    producers as a result of Photosynthesis.
  • Photosynthesis
  • 6CO2(g) 6H2O(l)
    C6H12O6(s) 6 O2(g)

Glucose or Food
  • Only an estimated 1 of the light that does reach
    the primary producers is actually converted into
    chemical energy by photosynthesis.

7
Examining Primary Productivity
  • Gross Primary Productivity (GPP)
  • Defined as the total amount of food created by
    plants in an area at any one time.
  • Net Primary Productivity (NPP)
  • Defined as the amount of food left to be passed
    on to the next trophic level after plants use
    some for their own purposes.
  • NOTE NPP is ALWAYS less than GPP!!!

8
Factors Affecting Primary Productivity
  • The factors that affect productivity in the
    various terrestrial and aquatic ecosystems
    include
  • light intensity,
  • temperature,
  • carbon dioxide availability,
  • availability of nitrogen and phosphorus,
  • latitude/altitude (terrestrial ecosystems) or
  • depth (aquatic ecosystems)

9
Food Chains
  • One possible path for the flow of energy in an
    ecosystem.
  • If the community has a great deal of
    biodiversity, there will be several organisms
    that can feed on more than one type of food
    resource, and as a result there would be several
    possible food chains.
  • Each step in the food chain is called a trophic
    level.
  • Corn ? Mouse ? Snake ? Hawk

10
Food Webs
  • All the possible Food Chains in an Ecosystem.

11
Food Chains and Energy Flow
  • What happens to energy as it flows along a food
    chain?
  • Energy is lost!!!
  • How?
  • Cellular Respiration is used to convert sugar in
    foods into energy for organisms to use, but at
    the same time some energy is lost as heat!!
  • Because energy is lost along the food chain,
    Pyramids of Energy, Biomass and Numbers are
    created.

12
Pyramid of Energy
  • The idea that each higher trophic level has less
    energy available to it.
  • 10 rule only 10 of the energy of one trophic
    level gets transferred to the next trophic level
    (90 is lost as heat)!!

13
Pyramid of Biomass
  • A pyramid that represents the total biomass of
    organisms at each trophic level.
  • Biomass -- The total dry weight of organisms in
    a trophic level.
  • Why dry weight?
  • Because amount of water varies in each ecosystem,
    so dry weight is used as a better measuring tool.
  • Pyramid is similar in structure to a pyramid of
    Energy. 10 rule.
  • There can be exceptions!!!!

14
Pyramid of Numbers
  • Pyramid that represents the total number of
    organisms that can be supported at each trophic
    level.
  • There can be exceptions!!!

15
Conditions Necessary for a Stable,
Self-sustaining or Sustainable Ecosystem
  • Stability means that there is an ecological
    balance between the various organisms that make
    up the food web, and because of this balance the
    ecosystem is self-sustaining over long periods of
    time.
  • To be stable there must be a balance between food
    production, food consumption, and decomposition
    of dead organisms and/or their wastes.

16
Keystone Species
  • A keystone species is one considered so important
    to the stability of the ecosystem, that if there
    was a decline in that species, the community
    would not be able to maintain its stability and
    may even collapse.
  • For example
  • sea otters in kelp forests keep sea urchins in
    check. Kelp roots are merely anchors, and not the
    vast nutrient gathering networks of land plants.
    Thus the urchins only need to eat the roots of
    the kelp, a tiny fraction of the plant's biomass,
    to remove it from the ecosystem.

17
Another Example of a Keystone Species
  • The beaver is another example of a keystone
    species.
  • It transforms its territory from a stream to a
    pond or swamp

18
  • Niche vs habitat

19
  • Habitat
  • the place were an organism lives.
  • The habitat of an organism is part of its niche.
  • The organism's habitat is its address - where it
    lives.
  • Every organism has its own habitat.
  • The habitat of slime molds is the damp floor of
    the forest.
  • The organism's habitat is were the organism is
    best adapted to survive.
  • a fish is adapted to life in water because it has
    gills to get oxygen.

20
  • A single area may satisfy the needs of many kinds
    of plants and animals. These organisms that
    associate together in a common habitat form
    communities.

21
  • For Example
  • The Pine Marten prefers to live in undisturbed
    mature coniferous or mixed forest, with large
    evergreens and scattered birch and other hardwood
    trees.
  • For denning and nesting sites, the martens uses
    hollow trees, stumps and logs.

22
  • Niche
  • The role that a species plays within its
    ecosystem.
  • In balanced ecosystems, each species occupies its
    own niche.
  • The niche is like the organism's profession -
    what it does to survive.
  • The function or position of an organism or
    population within an ecological community.
  • The particular area within a habitat occupied by
    an organism.

23
  • Competition
  • Organisms are forced to compete against their own
    species and also different species in order to
    survive.
  • The stronger and more fit organisms have an
    advantage over those who are weaker, and they
    have a better chance of surviving.

24
  • Competition arises when organisms have
    requirements in common and they must compete to
    meet their own needs.
  • The more needs organisms have in common, the more
    intense the competition.
  • When the resources that are being competed for
    become scarce the competition becomes more
    intense, and eventually one of the species
    becomes eliminated.

25
  • Habitats have finite amounts of the resources
    needed by living organisms, such as food, water
    and space, and all organisms strive to reproduce
    themselves and increase their numbers.
  • Sooner or later the demand for these resources is
    going to exceed supply, and organisms have to
    compete with each other to get them.

26
  • Plants typically compete with each other for
  • light (for photosynthesis)
  • water, and
  • nutrients (minerals)
  • Animals typically compete with each other for
  • food
  • water
  • mates (so they can reproduce), and
  • living space

27
  • Intra-specific competition
  • Competition between the same species
  • Many birds of the same species compete for the
    best nesting grounds.
  • In cases when food or water is scarce, members of
    the same species will compete for food in order
    to survive.
  • Bull moose competing for a mate

28
  • Inter-specific competition
  • Competition between different species
  • Different species often compete for space, food,
    or water.
  • Fox and coyote compete for the rabbit
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