Relationships Between Ecosystem and Environment

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Chapter 6

• Relationships Between Ecosystem and Environment

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Chapter 6

• 6.1 Implications of Ecosystem for Humans
  
• 6.2 Disturbance and Succession of Ecosystem
  
• 6.3 Selection by Environment in Ecosystem
  
• 6.4 Changes in Species and Ecosystem
  
• 6.5 Ecological Responses to Environmental Change
• 6.6 Human impact on Ecosystems

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• 6.1 Implications of Ecosystem for Humans
• Forest biomes provide us with 3.3 billion
  cubic meters of wood annually for fuel, building
  material, and paper. Some 15 of the world's
  energy consumption is derived directly from plant
  material. We have converted almost 11 of
  Earth's land area from forest and grassland
  biomes to agricultural systems.

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Figure 6.1 Conversion of grain to protein
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Figure 6.2 One-directional nutrient flow in
human society
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6.1.1 Ecosystem services and functions
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6.1.2 Ecosystem Management 1.clear operational
goals 2.sound ecological models and
understanding, 3.understanding of complexity and
interconnectedness 4.recognition of the dynamic
character of ecosystems
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5.attention to context and scale 6.acknowledgment
of ignorance and uncertainty 7.commitment to
adaptability and accountability 8.acknowledgment
of humans as ecosystem components
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6.2 Disturbance and Succession of Ecosystem
A stage of equilibrium which there is a dynamic
balance between all species and the physical
environment. This final state is referred to as a
climax ecosystem
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• 6.2.1 Ecological Succession
• Primary Succession
• If the area has not been occupied previously,
  the process of initial invasion and then
  progression from one biotic community to the next

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• Secondary Succession
• When an area has been cleared by fire or
  artificial means and then left alone, the
  surrounding ecosystem may gradually reinvade the
  area through a series of distinct stages

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• Aquatic Succession
• as lakes or ponds are gradually filled and
  taken over by the surrounding terrestrial
  ecosystem
• Ecosystems that depend on the recurrence of fire
  to maintain the existing balance are now referred
  to as fire climax ecosystems

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6.3 Selection by Environment in Ecosystem 6.3.1
Selection

• Gene pool
• All DNA sample from every individual of a
  species
• The genetic differences that exist among
  individuals as genetic variation in the
  population

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• Some individuals reproducing more than others, a
  phenomenon called differential reproduction
• A change in the gene pool of a species over the
  course of generations is the essence of
  biological evolution

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• The process is an arbitrary selection based on
  the breeder's choice and the breed is carefully
  maintained distinct from other breeds, we refer
  to it as artificial selection

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• A modification of the species' gene pool
  toward features that enhance survival and
  reproduction within the existing biotic community
  and environment. Since the process occurs
  naturally, it is known as natural selection

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• 6.3.2 Adaptations to the Environment
• The phrase "survival of the fittest" from The
  Origin of Species by Natural Selection (Charles
  Darwin,1859).
• Adaptations for coping with climatic and other
  abiotic factors

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• Adaptations for obtaining food and water in the
  case of animals, and nutrients, energy, and water
  in the case of plants.
• Adaptations for escaping from or protecting
  against predation and for resistance to
  disease-causing or parasitic organisms

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• Adaptations for reproduction to find or attract
  mates in animal populations and for pollination
  and setting seed in plant populations
• Adaptations for migration in the case of animals,
  and dispersal of seeds in the case of plants

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Figure 6.3 Adaptation for survival and
reproduction.
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6.4 Changes in Species and Ecosystem

• AdaptationThe population of survivors may
  gradually adapt to the new condition(s) through
  natural selection
• MigrationSurviving populations may migrate and
  find an area where conditions are suitable
• ExtinctionFailing the first two possibilities,
  extinction is inevitable

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Four key variables affect survive
1.geographical distribution 2.specialization to a
given habitat and/or food supply 3.genetic
variation within the gene pool of the
species 4.size of the organism
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Figure 6.4 Vulnerability of different
organisms to environmental changes.
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6.6 Human Impact on Ecosystems

• Tampering with Abiotic Factors
• Tampering with Biotic Factors