National 5

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National 5

• Biodiversity and the Distribution of Life

Mr G Davidson
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Biomes

• There are many different ecological areas across
  the world, each with its own distinct
  characteristics.
• These regions are called Biomes.
• Each biome has its own communities of animals
  (fauna) and plants (flora) which have adapted to
  live in these regions.

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Biomes
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Biomes

• Biomes are different from each other based on a
  number of abiotic factors such as rainfall and
  temperature.
• Abiotic factors are non-living and other examples
  include pH, light intensity, oxygen
  concentration, etc..

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Biomes

• There are also other factors which can affect the
  distribution of organisms, and these are called
  biotic factors.
• Biotic factors are a direct result of living
  things and include amount of food, number of
  predators, competition with other organisms,
  disease, etc..

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Ecosystems

• An ecosystem is a natural biological unit
  composed of both living and non-living parts.
• An ecosystem is made up of a number of habitats,
  which are the places where organisms live.

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Ecosystems

• All the living organisms in an ecosystem make up
  the community.
• Each organism has a specific role to play within
  an ecosystem and this is called the niche, and
  includes the interaction with other organisms as
  well as the use of resources from within the
  ecosystem.

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Biodiversity

• Biodiversity is the degree of variation that
  exists amongst all living organisms on Earth.
• It can be increased or decreased within
  ecosystems depending on which factors are
  influencing the populations, and by how much.

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Grazing

• Grazing is a biotic factor responsible for
  affecting biodiversity.
• If a particular area is under-grazed, the
  biodiversity is decreased.
• This is because the dominant plants eventually
  smother the less dominant plants, stopping them
  growing, and this results in fewer plant species
  growing.

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Grazing

• If a particular area is over-grazed, the
  biodiversity is also reduced.
• This is because all the plants are being grazed
  and this can result in some of the species of
  plants being wiped out, so reducing the
  biodiversity.

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Grazing

• If, however, an area is moderately grazed, this
  can increase the biodiversity.
• The dominant plants are kept in check by the
  grazers, allowing the more delicate plants to
  flourish because they get more resources.

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Predation

• Predation is a biotic factor which can also
  affect the biodiversity.
• Predators can be responsible for keeping
  populations of prey in check, and thus allow an
  increase in biodiversity.
• If predators are reduced or removed, the prey
  then increase in numbers and so this can lead to
  over-grazing and a reduction in the number of
  plant species.

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Predation
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Temperature

• Gases such as carbon dioxide and nitrous oxide
  are released when fuels are burned.
• They are responsible for trapping the Earths
  heat causing global warming.
• The knock on effect of this is the melting of the
  polar ice caps and flooding.

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Temperature

• Temperature is also responsible for affecting the
  biodiversity of fish.
• A temperature increase in water reduces the
  amount of oxygen present in the water and
  therefore reduces the biodiversity of fish
  species.

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pH

• When fossil fuels are burned they release sulphur
  dioxide and nitrogen dioxide.
• These gases dissolve in water in the clouds and
  this lowers the pH making the rain acidic.

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pH

• This acid rain damages plant leaves which reduces
  photosynthesis and therefore the amount of plant
  material available for animals to eat.
• Acid rain also dissolves nutrients in the soil
  meaning less are available for plants.

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pH

• Acid rain is also responsible for reducing the pH
  of freshwater.
• This reduces the numbers of certain species of
  fish therefore reducing the biodiversity.

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The Impact of Humans

• Humans have a huge impact on biodiversity in a
  number of ways, as well as those already covered.
• With the increase of the human population and the
  improvements in technology, this has led to human
  over-exploitation.

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The Impact of Humans

• Some species of animal are in danger of
  extinction due to over-hunting, mainly for food,
  but also for skins or simply trophies.
• Over-fishing has reduced the numbers of the
  populations of certain species of fish.
• Fishing quotas have been put in place to try to
  prevent this worsening.

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The Impact of Humans

• Over-grazing of land is another major problem in
  some countries.
• This has resulted in soil erosion which means the
  soil can no longer be used to grow plants which
  return nutrients to the ground.
• The result is that no crops can be grown.

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Habitat Destruction

• Tropical rainforests are being cut down to create
  farmland to replace the land which has been
  over-grazed.
• This deforestation leads to the extinction of
  many species and the reduction of other
  population numbers.
• Habitats are being removed and the organisms left
  are subject to even greater competition.

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Habitat Destruction

• Over-farming of land, in order to meet the food
  demand, leads to the removal of nutrients from
  the soil.
• This results in reduced vegetation which in turns
  leads to soil erosion when the rain comes.
• This process is called desertification.

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Endangered Species

• Endangered organisms are on the verge of
  extinction.
• Some organisms are endangered due to human
  activity such as introducing new species to a
  certain habitat.
• This new species then ousts the native species
  and so reduces biodiversity, e.g. Japanese
  knotweed.

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Pollution

• Pollution is the addition of something to the
  environment which causes harm.
• Water can be polluted in a number of ways
• Litter this can kill animals which live in the
  water as they may eat the litter.
• Organic waste this provides food for bacteria
  and so their numbers increase leading to a
  reduction of oxygen in the water, and so reducing
  the biodiversity.

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Pollution

• Air can also become polluted due to the effects
  of humans, like the production of sulphur
  dioxide.
• Some plant species such as lichens are very
  sensitive to air pollution.
• We call these species indicator species because
  they give us information about the state of an
  ecosystem, i.e. if the lichen is present the air
  is unpolluted and vice versa.