Populations and Sustainability

1
Populations and Sustainability

• Explain the significance of limiting factors in
  determining the final size of a population
• Explain the meaning of the term carrying
  capacity
• Describe predatorprey relationships and their
  possible effects on the population sizes of both
  the predator and the prey
• Explain, with examples, the terms interspecific
  and intraspecific competition
• Distinguish between the terms conservation and
  preservation (HSW6a, 6b)
• Explain how the management of an ecosystem can
  provide resources in a sustainable way, with
  reference to timber production in a temperate
  country
• Explain that conservation is a dynamic process
  involving management and reclamation
• Discuss the economic, social and ethical reasons
  for conservation of biological resources (HSW6b,
  7c)
• Outline, with examples, the effects of human
  activities on the animal and plant populations in
  the Galapagos Islands (HSW6b).

2
Limiting Factors

• Population size stays stable, but can also rise
  and fall suddenly
• Population size is a balance between death rate
  and rate of reproduction

3
Population Growth

• Lag Phase a few individuals acclimatising to
  their habitat. Growth and reproduction is slow
• Log Phase resources are plentiful and conditions
  are good. Reproduction is greater than mortality.
  The population increases
• Carrying Capacity population has levelled out.
  The habitat cannot support a larger population.
  Reproduction rates equal mortality rate.
  Population stays stable or fluctuates very
  slightly

4
Why is there a carrying capacity?

• The habitat has factors which limit the growth of
  the population size
• These are called limiting factors
• Examples food, water, light, oxygen, nesting
  sites or shelter, parasites or predators,
  intensity of competition within and between
  species

5
Predator Prey Relationships

• Predator animal that hunts other animals for
  food
• Prey eaten by predator
• Predation can act as a limiting factor

6
populations and sustainability

• Describe predator prey relationship

7
Predator Prey Graph
Snowshoe Hare
Lynx
1. Predator population gets bigger, more prey
eaten
2. Prey population decreases- less food for
predators
3. Fewer predators survive and they decrease
4. Fewer prey now eaten and numbers increase
5. More prey, so predator numbers increase and
the cycle begins again
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Predator Prey Graph Limitations

• Predators may eat more than one type of prey
• Predation shown as the main limiting factor and
  disease/ hunting etc. not taken into account
• This gives the graph a less defined pattern

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Populations and Sustainability

• Explain the significance of limiting factors in
  determining the final size of a population
• Explain the meaning of the term carrying
  capacity
• Describe predatorprey relationships and their
  possible effects on the population sizes of both
  the predator and the prey
• Explain, with examples, the terms interspecific
  and intraspecific competition
• Distinguish between the terms conservation and
  preservation (HSW6a, 6b)
• Explain how the management of an ecosystem can
  provide resources in a sustainable way, with
  reference to timber production in a temperate
  country
• Explain that conservation is a dynamic process
  involving management and reclamation
• Discuss the economic, social and ethical reasons
  for conservation of biological resources (HSW6b,
  7c)
• Outline, with examples, the effects of human
  activities on the animal and plant populations in
  the Galapagos Islands (HSW6b).

10
Georgyi Frantsevitch Gause

• Outline the study on Interspecific competion in
  paramecium carried out by Gause in 1934

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Gause

• Findings
• 2 species of paramecium grown separately and
  together
• Together, competition for food arose, paramecium
  aurelia more successful than paramecium caudatum
  which died out
• Conclusions
• The more overlap between two species niche, the
  more intense the competition
• If two species have the same niche, onw would die
  out in that habitat
• This is known as the competitive exclusion
  principle
• This explains why particular species only grow in
  particular places

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populations and sustainability

• Explain with examples interspecific and
  intraspecific competition

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Competition

• Occurs when a resource is in short supply
• As competition increases, reproduction decreases,
  death rate increases
• Intraspecific competition between organisms of
  the same species e.g. lions
• Interspecific competition between organisms of
  different species e.g. lions and hyenas

15
Is extinction always inevitable?

• Sometimes, between two species, one just gets
  smaller and both populations then remain quite
  constant
• In the lab other variables are not taken into
  account e.g. temperature

In the lab, T. Castaneum increased their
population size, but a change in temperature
would mean that T. Confusum was successful
T. Castaneum
VS.
T. Confusum
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• Limiting factors (e.g. space, food, light) create
  a carrying capacity maximum population of a
  species that an environment can support. It is
  often the factor in the shortest supply
• Predator-prey cycle increased prey numbers
  predator numbers increase as more food leads to
  decrease in prey predator numbers fall increase
  numbers of prey, etc.
• Intraspecific competition is between individuals
  of the same species competing for a mate, food
  or nest site.
• Interspecific competition is between individuals
  of different species different plant species
  competing for light/soil/water/nutrients, etc.

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Populations and Sustainability

• Explain the significance of limiting factors in
  determining the final size of a population
• Explain the meaning of the term carrying
  capacity
• Describe predatorprey relationships and their
  possible effects on the population sizes of both
  the predator and the prey
• Explain, with examples, the terms interspecific
  and intraspecific competition
• Distinguish between the terms conservation and
  preservation (HSW6a, 6b)
• Explain how the management of an ecosystem can
  provide resources in a sustainable way, with
  reference to timber production in a temperate
  country
• Explain that conservation is a dynamic process
  involving management and reclamation
• Discuss the economic, social and ethical reasons
  for conservation of biological resources (HSW6b,
  7c)
• Outline, with examples, the effects of human
  activities on the animal and plant populations in
  the Galapagos Islands (HSW6b).

18
Conservation VS. Preservation

• Conservation Management of ecosystems so that
  the natural resources in them can be used without
  them running out. E.g. timber management. It can
  also be reclamation restoring ecosystems that
  have been damaged or destroyed. It is dynamic and
  needs to adapt to constant change
• Preservation protecting ecosystems so they are
  kept exactly as they are. Nothing is removed and
  they are only used for activities that dont
  damage them

19
Sustainable Management and Timber Production

• Using OCR Biology p208-209, explain how the
  management of an ecosystem can provide resources
  in a sustainable way using timber production as
  an example

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Sustainable Management and Timber Production

• Population increasing exponentially
• More intensive methods used to exploit
  environmental resources destroying ecosystems,
  reducing biodiversity and depleting resources
• Especially apparent in timber industry due to a
  growing need for wood
• Sustainable management is possible maintaining
  biodiversity, sustaining timber companies and
  also our supply of wood
• Can be small and large scale

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Small Scale Timber Production

• Involves coppicing
• Harvesting wood keeping tree alive
• Trunk cut close to ground
• New shoots form from the cut surface and mature
• These shoots are eventually cut and again are
  replaced by more
• Shoots are used for fencing etc.
• Pollarding is similar but the trunk is cut higher
  up so deer cannot eat the new shoots
• Rotational coppicing where woodland is divided
  into sections and only cut in the particular
  section until all have been coppiced, then the
  cycle begins again- some trees are not coppiced
  and are known as standards
• Rotational coppicing is good for biodiversity.
  The trees never grow enough to block out the
  light, so succession cannot happen and more
  species can survive

22
Timber Production management

• Involves coppicing
• Harvesting wood keeping tree alive
• Trunk cut close to ground
• New shoots form from the cut surface and mature
• These shoots are eventually cut and again are
  replaced by more
• Shoots are used for fencing etc.
• Pollarding is similar but the trunk is cut higher
  up so deer cannot eat the new shoots
• Rotational coppicing where woodland is divided
  into sections and only cut in the particular
  section until all have been coppiced, then the
  cycle begins again- some trees are not coppiced
  and are known as standards
• Rotational coppicing is good for biodiversity.
  The trees never grow enough to block out the
  light, so succession cannot happen and more
  species can survive

Pollarding
coppicing
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Large Scale Timber Production

• Mostly clear felling cutting down large areas
  of forest
• Habitats destroyed, soil minerals reduced and
  soil left susceptible to erosion. Soil can also
  run into water and pollutes them
• Trees remove water from soil and maintain
  nutrient levels through the carbon and nitrogen
  cycle
• Leaving woodland to mature for up to 100 years
  allows biodiversity to increase however this is
  not a timescale that would be effective
  nowadays... However companies nowadays ensure

• Trees can be replaced by replanting
• The biodiversity, mineral and water cycles are
  maintained
• Local people must still benefit from the forest
• Selective cutting involves removing only the
  largest trees
• More wood is supplied per tree as pests and
  pathogens are managed, only well growing trees
  are planted and they are placed an optimal
  distance apart to reduce competition

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• Selective cutting involves removing only the
  largest trees
• Trees cleared in patches woodland grows more
  quickly in smaller areas between bits of existing
  woodland than in larger open spaces. Less soil
  erosion will occur.
• Coppicing and pollarding
• Only plant native species as they are adapted to
  the climate
• New trees attached to a post for support and
  covered with plastic tubes to stop them being
  eaten.
• Planted with optimum space between to reduce
  competition.
• More wood is supplied per tree as pests and
  pathogens are managed.

25
Populations and Sustainability

• Explain the significance of limiting factors in
  determining the final size of a population
• Explain the meaning of the term carrying
  capacity
• Describe predatorprey relationships and their
  possible effects on the population sizes of both
  the predator and the prey
• Explain, with examples, the terms interspecific
  and intraspecific competition
• Distinguish between the terms conservation and
  preservation (HSW6a, 6b)
• Explain how the management of an ecosystem can
  provide resources in a sustainable way, with
  reference to timber production in a temperate
  country
• Explain that conservation is a dynamic process
  involving management and reclamation
• Discuss the economic, social and ethical reasons
  for conservation of biological resources (HSW6b,
  7c)
• Outline, with examples, the effects of human
  activities on the animal and plant populations in
  the Galapagos Islands (HSW6b).

26
Conservation VS. Preservation

• Conservation maintenance of biodiversity
  including diversity between species, genetic
  diversity within species and maintenance of
  habitats
• Preservation protecting areas of land unused by
  humans

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Importance of conservation

• Economic provide resources that humans need e.g.
  rainforests species provide drugs, clothes and
  food which are traded.
• Social Many ecosystems are enjoyed and used for
  activities e.g. birdwatching!! They should be
  conserved for the enjoyment of future generations
  too
• Ethical organisms have a right to exist and we
  have a moral responsibility to future generations

28
populations and sustainability

• Outline effects of human activity in the
  Galapagos Islands

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Human activities have effected the Galapagos
Islands

• A small group of Islands in the Pacific Ocean.
• Many species of animals and plants have evolved
  here that cant be found anywhere else.
• E.g. Galapagos giant tortoise and the Galapagos
  sea lion.
• http//www.youtube.com/watch?vXpblfFd6a5A
• http//www.youtube.com/watch?vMLX4tkwwieM
• http//www.youtube.com/watch?vNHAz1ak2sqY

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Activity effect

• Eating them
• Non-native animals introduced eat native species
• Non-native plants out-complete native species
• Fishing
• Tourism
• 1991- 41 000 tourists
• -2008-160 000 tourists
• Island population increased

• Explorers in 19th Centuary hunted a type of Giant
  Tortoise to extinction on Floreana Island
• Non-native dogs, cats and black rats eat young
  giant tortoises and Galapagos land iguanas. Pigs
  also destroy the nests of iguansas and eat their
  eggs. Goats have eaten much plant life.
• Reduced population of sea cucumbers and
  hammerhead sharks. Galapagos green turtles are
  accidentally killed in nets and are now
  endangered.
• Development on islands e.g. airport on Baltra
  Island land cleared, pollution, pressure on
  drinking water and energy supplies
• Increased opportunities from tourism more
  development

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Steps taken

• Restrictions on visiting the uninhabited islands
• Marine reserves
• Culling alien species e.g. goats and destroying
  invasive plants eg. Elephant grass
• Captive breeding and reintroduction e.g. giant
  tortoises
• Inspecting visiting boats for alien species.

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• Preservation is the protection of an area by
  restricting or banning human exploitation or
  contact nature reserves/preserves/parks.
• Conservation is maintaining biodiversity but
  allowing sustainable production replanting
  mixed tree species after felling for timber.
• Management (grazing or water level control) and
  reclamation (preventing succession by draining)
  are part of conservation.
• Conservation is for economic (timber industry),
  social (recreation) and ethical (preventing
  species extinction) reasons.

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Questions

• 1. Define and list limiting factors
• 2.Explain the meaning of the term carrying
  capacity
• 3.Describe predatorprey relationships and their
  possible effects on the population sizes of both
  the predator and the prey
• 4. Explain, with examples, the terms
  interspecific and intraspecific competition
• 5. Distinguish between the terms conservation and
  preservation
• 6. why does conservation need to be dynamic?
  (gre/rev/96)
• 7. what is meant by reclamation? (gre/rev/96)
• 8. Explain how the management of an ecosystem can
  provide resources in a sustainable way, with
  reference to timber production in a temperate
  country
• 9.Discuss the economic, social and ethical
  reasons for conservation of biological resources
• 10.Outline, with examples, the effects of human
  activities on the animal and plant populations in
  the Galapagos Islands and the steps taken to aid
  conservation.

34
Use words or pictures to show what you think 500
years before 1 year before 6months after 10 years
after
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Deforestation is a necessary evil

• Deforestation is a necessary evil