Energy flows, Trophic levels,

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Energy flows, Trophic levels, Food chains
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Recap from last lesson

• At the end of last lesson you were finishing off
  a map (Page 94- fig 1)
• The idea was to identify the relationship between
  Climate, Soils and Vegetation

World Climate
Zonal Soils
Vegetation zones
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Key words from last lesson

• Biotic-
• Living organisms (Animals, Micro-Organisms, Trees
  and other Plants)
• Abiotic-
• Inorganic (physical) and chemical elements of the
  ecosystem (Soil, Climate, Relief, Geology and
  Drainage)

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The Components of an Ecosystem
Climate
Vegetation
Soils
Animals
People
The flow of energy and the cycle of nutrients
maintain the equilibrium in the ecosystem.
Upsetting the balance can seriously affect the
system
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Other key concepts from last lesson

• Ecosystems exist at many scales
• e.g. A small hedgerow is an ecosystem, as is a
  rock pool. We went out to have a look at the
  hedge surrounding the school
• The Tropical Rainforest is an example of an
  ecosystem at an immense scale.
• We call this a Biome

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Organic Elements

• We have already covered the concept that an
  ecosystem is a link between organic and inorganic
  elements
• Before we cover the processes in an ecosystem, we
  need to understand what makes up the Organic
  elements in an ecosystem

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Organic Elements

• There are 2 organic elements in an ecosystem
  which link with the inorganic elements. These
  are-
• Biomass
• Dead organic matter

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Biomass

• This is the amount of living matter in the
  ecosystem at any one time
• It includes living matter above ground (e.g.
  leaves/animals) and below ground (e.g.
  roots/burrowing animals)
• We measure it in dry weight per area
• e.g. tonnes per hectare or kg per m²
• Different ecosystems / biomes have differing
  biomass- Tropical rainforest has a large biomass
  Arctic Tundra a very small biomass

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Dead organic matter

• This includes-
• On the surface of the soil- The litter layer
  (leaves branches yet to decay)
• Soil humus- the organic matter that has
  decomposed and become part of the soil
• In most ecosystems dead organic matter is less
  than biomass. Sometimes it can be the other way
  around (often in Tundra)

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Processes in an ecosystem

• Key terms- Energy flow, Food chain, Trophic
  Levels
• The intention here is to go over with you what
  you already know from GCSE Science / Geography.
• Instead of copying lots of notes that most of
  you will know I will talk to you about the key
  concepts and give you some time to make your own
  notes on the subject

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• Photosynthesis- green plants- primary producers
• Primary consumers- herbivores
• Secondary consumers- carnivores
• Tertiary consumer- carnivores
• Food chain- Trophic Levels
• Energy loss at each level- up to 90
• 10 efficiency

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Pyramids of number
Usual
Birds
Unusual
Caterpillars
Cabbage
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Pyramids of biomass
50 kg
Young human
Beef Cattle
1000 kg
Animal fodder
8000 kg
Your job is now to use the information we have
just spoke about, and page 96 97 to make your
own notes on energy flows, food chains, trophic
levels, and pyramids
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Nutrient Cycling
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How the system works

• From GCSE you will be familiar with systems
  having inputs, outputs, flows and stores
• They may be open or closed systems
• Plants and animals need nutrients to live
• The nutrients are gained and lost from within the
  ecosystem that they live in
• This is the simple concept of the cycle of
  nutrients
• From GCSE you will probably be familiar with the
  Carbon or Nitrogen cycle

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How the system works- continued

• The nutrient cycles occur between the Biotic and
  Abiotic elements of the ecosystem

Copy this pic and add any notes you might need
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What humans do-

• Positive
• Add organic fertiliser
• Add inorganic fertiliser (?)
• Plant new trees / plants
• Negative
• Deforestation
• Over-farming
• Irrigation (leach nutrients)
• Harvesting

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Analysis of one sub-cycle in detail(required
as part of the syllabus)
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• You have been given a copy of this picture.
• Use the picture to describe what exactly it is
  all about
• It is also explained for you on page 98

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Productivity (energy absorption)(this is pretty
dull, but yet again, on the syllabus)

• Gross Primary Production (GPP) is
• energy that is absorbed and used for life
  processes and growth
• Net Primary Production (NPP) is
• the element that is used for growth only

In simple terms this means that the NPP is the
growth rate of the vegetation in an ecosystem
(increase in the Biomass over the year)
As with the plants in any garden, the rate the
biomass increases depends upon light, heat,CO2,
H2O and nutrients
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• Humans can affect productivity through the way
  that they undertake agricultural projects
• e.g. selective breeding, using machinery,
  fertilisers, or becoming vegetarian (more people
  can be fed from an field of wheat than if we used
  that field to graze animals)

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Candidates are to select one global biome and
develop an understanding of its unique
characteristics

• We have 2 choices here-
• A low productivity ecosystem- Arctic Tundra
• A high productivity ecosystem- Rainforest

• You need to develop a case study IN DETAIL of
  one of the above
• Use the textbook, but more importantly, make the
  case study easy to revise from- use photos,
  diagrams etc
• Its not just copying from the textbook- BUT the
  headings used as subtitles in the textbook might
  be useful.
• You need to consider Nutrients, Productivity and
  Human impacts