National Diploma in Countryside Management

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National Diploma in Countryside Management

• Unit 2
• Principles of Ecology
• Session 8 Energy and Nutrient in Ecosystems
• Tutor Robert Mackey

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Aims of the session

• Identify cycling processes in ecosystems
• Define the parts of the processes
• Consider the importance of cycling processes in
  ecosystems
• Exercise to identify webs within the survey area

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Cycles in ecosystems
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Producers

• Producers are organisms that use the sun's energy
  to make food
• Note there are a few examples of other energy
  sources (e.g. sulphur in deep water)
• They are autotrophs
• Includes most plants
• Energy is stored as chemical bonds within the
  tissues of the organism
• The energy becomes available to other organisms
  in the ecosystem

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Consumers

• Consumers are organisms that are not producers!
• They are heterotrophs
• They require energy from other organisms to
  sustain themselves
• Likely to obtain their nutrients too
• Consumers include
• Animals (herbivores and carnivores)
• Micro-organisms (most)
• i.e. Everything except plants!
• Includes decomposers

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Decomposers

• Decomposers are
• A specialised type of consumer
• Fundamental to life on earth
• The break down the organic remains of other
  (dead) organisms
• They release energy from as either
• Decomposer biomass (for consumption) or
• Carbon dioxide (for photosynthesis)
• Includes
• Worms,
• Some bacteria and some fungi

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Energy Transfer

• Energy ecosystems allows organisms to live
• One original source photosynthesis
• Plants use this solar energy to produce
  carbohydrates
• Consumed by other organisms
• Transfers the energy.
• System is not efficient

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Energy Transfer

• Not all of the energy from sunlight is used by
  the plants
• Plants are not efficient
• Much sunlight misses the plant
• Or is in the wrong wavelength
• Or lost in the inefficiencies of photosynthesis
• Or used by the plant itself
• Gross primary production is the total energy in
  the molecules of the plant
• Net primary production is the surplus energy not
  used by the plant itself.

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Efficiency of Energy Transfer

• At each level of the food chain energy is lost
  because it is used by the organism itself for
  respiration. This limits the number of steps
  there can be on a food chain.
• Generally only about 8 of the energy is
  transferred from one stage to the next.

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Pyramid of Number

• The number of individuals at each trophic level
  varies
• See diagram
• The length (or area to be more accurate) of each
  bar is proportional to the number of individuals.
  

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Food Chains

• A food chain shows how energy is transferred
  between organisms
• The energy from sun
• Plants convert into chemical energy
  (photosynthesis)
• Herbivores eat the plants, taking some of the
  energy
• They are prey, energy is transferred to the
  predator.

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Food Chains

• A food chain is a simple series of feeding
  relationships within an ecosystem
• Example
• Rose bush --gt caterpillars --gt robin --gt
  sparrowhawk
• There is a flow of energy through the food chain
• Some energy in the rose bush is consumed by the
  caterpillars
• Some of the energy n the caterpillars is consumed
  by the robin
• Some of the energy in the robin is consumed by
  the sparrowhawk 
• All food chains begin with energy from the sun

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Food Chains

• All food chains begin with energy from the sun
• The transfer of energy from level to level is
  inefficient
• Transfer efficiency may be as low as 1
• Numbers of producers must be large
• Numbers reduce up the food chain
• A food web is a (complex) series of inter-related
  food-chains

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A simple food web
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Cycling in ecosystems

• Cycling/webs in ecosystems include
• Energy
• Water
• Carbon/Carbon Dioxide
• Nutrient
• Potash, Phosphate and minor elements
• Nitrogen
• Water

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A food web
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Nitrogen Cycling
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Carbon Cycling

• Currently very significant
• Carbon makes up 50 of all organisms
• Links to producers/consumers
• CO2 is a greenhouse gas
• Exists naturally in the atmosphere
• Modifies radiation in/out of earth
• Increased levels increase temperature
• 25 increase since 1850

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Carbon Dioxide in the Atmosphere

• Increased CO2 caused by
• Natural decomposition of organic matter
• Burning of fossil fuels
• Changes to land use
• Deforestation
• Soil cultivation
• Release from oceans
• Decreased CO2 caused
• Photosynthesis (plant growth)
• Absorption by oceans
• Improved soil management

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Task

• Consider your survey area
• Identify food webs in the ecosystem
• Use correct binomial names
• What are the producers?
• What do they contribute to the eco-system?
• What are the consumers
• What are they taking from the systems
• What are they contribution
• What can we do about it?
• How do we improve
• Nutrient recycling
• Carbon sequestration (Fixing)