World Geography 3202

1
World Geography 3202

• Unit 3
• Ecosystems

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Introduction

• Unit 3 focuses on the interrelationships between
  landforms and water forms on the one hand and
  climate on the other, and how these
  interrelationships make up the earths
  ecosystems.
• Soils, which result from a complex interaction
  among climate, land, flora and fauna, form a
  vital resource that humans use to satisfy needs
  and wants.
• Humans must exercise wise stewardship in order to
  conserve resources

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An ecosystem consistsof a complex network of
organisms

• Ecosystem The network of relationships among
  plants, animals and the non-living constituents
  in the environment.
• It is composed of
• Producers Organisms capable of making their own
  food supply from solar energy, thus making them
  necessary for supplying the energy for all of
  life.
• Consumers Animals that must eat producers and
  other consumers in order to survive

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An ecosystem consistsof a complex network of
organisms

• Decomposers Live in soil or water and include
  bacteria, fungi, and mold.
• They break down wastes of other consumers and the
  decaying tissue of dead organisms into basic
  chemical compounds and nutrients.
• These decomposed substances are returned to the
  environment to be reused by plants for growth and
  food production.
• Primary Consumers Herbivores, those animals
  whose only source of energy is green plants.
• Secondary Consumers Those organisms who survive
  on the energy of producers and primary and
  secondary consumers

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Ecosystem
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An ecosystem consistsof a complex network of
organisms

• Starting with the sun, sending its energy to
  plant producers, and continuing on through every
  instance of one organism consuming another,
  energy is constantly begin transferred, or passed
  on, through life forms.
• This transference is called a Food Chain

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An ecosystem consistsof a complex network of
organisms

• A food chain is relatively simplistic, often with
  five links or less
• Producer --- Primary Consumer --- Secondary
  Consumer --- Tertiary Consumer
• In most ecosystems, there are many overlapping
  food chains, because most organisms obtain energy
  from different sources.
• Consequently, the relationship of organisms in
  competition for various energy sources in a given
  ecosystem is better described as a Food Web

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Food Web
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Energy flow through an ecosystem

• Solar Energy is delivered to plants
• Plants deliver oxygen to atmosphere, take in
  Carbon Dioxide, and serve as food for Primary
  Consumers
• Primary Consumers are consumed by Secondary
  Consumers
• Secondary by tertiary, and so on
• At each level of transference, energy is lost
  only 10 to 15 percent of the energy used by the
  food source is consumed by the next level
  Therefore secondary and tertiary consumers are
  terrible energy wasters

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Energy flow through an ecosystem
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Food Pyramids

• The food pyramid diagram can be used to
  illustrate energy flow in food chains and food
  webs.
• The pyramid shape of the diagram derives from the
  fact that a steadily decreasing amount of energy
  is available at each new level in the food chain.
• As a result of competition, the number of
  organisms that can be supported at each new level
  decreases.

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Food Pyramids
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Food Pyramids

• The base of the pyramids represents the amount of
  energy supplied by all the plants or producers in
  an ecosystem.
• The layer above the base represents the number of
  primary consumers that can be supported by the
  producers
• The layering continues until, in theory, only one
  carnivore can be supported at the top.
• Each of these layers is known as a Trophic Level.

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The relationshipsamong the living and non-living
elements of an ecosystemare delicately balanced

• Biological Amplification
• When consumers at higher levels in a food chain
  eat organisms that have toxic chemicals in their
  tissues, they receive a higher concentration of
  the toxins than did the lower level organisms.
• Two factors are involved in this magnification.
• First Toxic chemicals are fat soluble. This
  means they collect in fatty tissues and do not
  get flushed with waste.
• Second The higher up the food chain an organism
  is, the more of organisms it has to consume to
  keep energy levels up, as it only receives
  approximately 10 percent of that organisms
  energy in transference.

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Predict the effect on an ecosystem of the
introduction of a new organism

• In groups, complete question 13, p. 99

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The general characteristics of a given ecosystem

• All life forms seem to be specially suited to the
  physical characteristics of the ecosystem that
  they inhabit.
• The one feature that is most essential for
  identifying a given ecosystem is its climax
  vegetation The chief vegetation that has
  developed in a region over a long period of time,
  given a particular climate.

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The general characteristics of a given ecosystem
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The general characteristics of a given ecosystem
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The general characteristics of a given ecosystem
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• The factors that affect soil quality
• Soil develops from a complex interaction of
  several processes occurring over centuries.

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The quality of a soil in terms of its soil
texture

• Soil quality or fertility is measured in terms of
  a soils hums content relative to the amount of
  ground-down bedrock it contains.
• The key factor that causes variance in soil
  profiles is climate
• Climate provides the moisture needed for the
  weathering process at the beginning of soil
  formation, as well as the precipitation and dry
  heat needed for leaching, eluviations and
  capillary action to occur.

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The quality of a soil in terms of its soil texture

• A key component in determining a soils value is
  its texture.
• Texture refers to the types of particles in the
  soil
• Both particle size and the extent to which
  particles bond to one another affect soil
  quality.
• These characteristics of particles determine how
  much water will flow through the soil, the water
  holding capacity of the soil, and air movement
  through the soil.

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The quality of a soil in terms of its soil texture

• The three smallest components, Sand, Silt, and
  Clay, are the principal components of soil.
• At one extreme, Sandy soil, is loose and coarse.
  Water and air penetrate easily, making for easy
  drainage and rapid warming. It is so loose,
  however, that moisture needed for large scale
  plant growth is not retained.
• The other extreme is clay soil, which consists of
  fine grains of silicate material containing
  aluminum and water. This tends to hold water
  like a sponge and does not permit air to pass
  through. The soil is slow to warm up, slow to
  drain and hard to work.

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The quality of a soil in terms of its soil texture

• The most desirable soil texture for farmers is a
  balanced combination of soil, clay and silt
  particles, forming loam.

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Global patterns related to soil loss
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Global patterns related to soil loss

• Certain regions enjoy more fertile soil than
  others.
• However all regions are subject to soil
  degradation
• Soil can be degraded or lost in a very short
  period of time
• The most common cause of soil loss is water
  run-off.
• Other factors include urban expansion,
  overgrazing, flooding, and deforestation
• Desertification The degradation of land into
  arid and semi arid states through careless land
  use such as overgrazing.

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Global patterns related to soil loss

• Based on this chart, where is the loss of soil
  the greatest? The least?

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Global patterns related to soil loss
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Assess statements about soil availability

• In Africa Only 16 per cent of the land is
  suitable for farming
• In Southern Asia Only 20 per cent of the land is
  suitable for farming
• In Central and Northern Asia Only 10 per cent of
  the land is suitable for farming
• In Europe a fairly large amount of the soil is
  suited to farming

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Possible short-term and long-term impacts of a
threat to an ecosystem

• Examine the case studies on pp. 117- 129 for
  various reasons for threats to ecosystems, the
  causes for the threats and the results.