Ecosystems part two 

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  • Ecosystems part two
    • energy transfer in ecosystems
      • the feeding relationship in any ecosystem are often times more complex with many organisms feeding of many other organisms through several trophic levels
        • as such we often show these relations through a food web
          • how energy is transferred
            • energy transfer in ecosystems
              • the feeding relationship in any ecosystem are often times more complex with many organisms feeding of many other organisms through several trophic levels
                • as such we often show these relations through a food web
                  • how energy is transferred
                    • Their is often a loss of energy as you work your way up the trophic levels
                      • there is energy lost the through the life process that the prey undergoes
                      • their is also alot of energy that is stroed in parts of animals that the predators cannot digest this ergy is available for decomposers such as fungi and bacteria
                      • due to this decrease in energy as you go up the trophic levels the less predators you get
                        • this is often demonstrated by pyramids of numbers that look at the number of organisms at each trophic level
              • measuring the efficiency of energy transfer
                • pyramids of biomass
                  • this gives a greater measure of how the relationships in an ecosystem work and how energy transferred from organism to organism
                  • this is worked out by taking the wet mass of an animal then working out the dry mass from previously recorded data
                    • this way is less destructive to the ecosystem
                • pyramids of energy
                  • this is used to work out the actual amount of energy that is passed on from organism to organism
                  • to do this you take an dead animal and burn it measuring how much energy is released using a calorimeter
                  • this is often highly destructive to an ecosystem and takes a lot of time so most revert to using pyramids of biomass
                • productivity
                  • the pyramids of energy and biomass both have limitations
                    • biomass limitations
                      • different species may release different amount of ergys
                  • this looks at the rate at which energy passes through each trophic level
                  • it is a measure of the energy flow through the trophic levels
                    • the base of this pyramid is alway the primary producer
                      • the gross primary productivity is the rate at which plants convert light into chemical energy
                        • however energy is lots when the plants respire the difference between the amount of energy made and the amount of energy respired
                          • is called the net primary productivity
            • Their is often a loss of energy as you work your way up the trophic levels
              • there is energy lost the through the life process that the prey undergoes
              • their is also alot of energy that is stroed in parts of animals that the predators cannot digest this ergy is available for decomposers such as fungi and bacteria
              • due to this decrease in energy as you go up the trophic levels the less predators you get
                • this is often demonstrated by pyramids of numbers that look at the number of organisms at each trophic level
      • measuring the efficiency of energy transfer
        • pyramids of biomass
          • this gives a greater measure of how the relationships in an ecosystem work and how energy transferred from organism to organism
          • this is worked out by taking the wet mass of an animal then working out the dry mass from previously recorded data
            • this way is less destructive to the ecosystem
        • pyramids of energy
          • this is used to work out the actual amount of energy that is passed on from organism to organism
          • to do this you take an dead animal and burn it measuring how much energy is released using a calorimeter
          • this is often highly destructive to an ecosystem and takes a lot of time so most revert to using pyramids of biomass
        • productivity
          • the pyramids of energy and biomass both have limitations
            • biomass limitations
              • different species may release different amount of ergys
          • this looks at the rate at which energy passes through each trophic level
          • it is a measure of the energy flow through the trophic levels
            • the base of this pyramid is alway the primary producer
              • the gross primary productivity is the rate at which plants convert light into chemical energy
                • however energy is lots when the plants respire the difference between the amount of energy made and the amount of energy respired
                  • is called the net primary productivity
    • manipulating energy transfer
      • improving primary productivity
        • the npp in plants grown in fields is about 1-3%
          • by changing factors you can improve this
        • light intensity
          • this can be improved by planting them earlier to provide a longer growing season to harvest light
          • grow them under light banks
        • lack of water
          • irrigating crops
          • breeding drought resistant crops
        • temperature
          • planting crops earlier so the temperature has less of an impact on final yield
          • using a greenhouse
        • Lack of nutrients
          • crop rotation with nitrogen fixing plants like legumes
          • fertilisers
        • dealing with pests
          • spraying crops with pesticides
          • introducing natural predators to the pests
          • breeding pants to be pest restant
        • dealing with fungi and weeds
          • genetic modification
          • spray crops with fungicides
          • breed them to be resistant to fungi
        • what can hinder primary productivity
          • weeds that compete with crops
          • fungi that attack xylem vessels damage foliage so preventing photosytesis
            • damage phloem and damage the flowers and fruits this prevents reproduction
          • pests eat plants reducing biomass and stored energy as well as lower the yield
          • low temperature limits the speed of reactions
          • lack of water and light limit photosynthesis so lower the amount of energy that can be produced
      • improving secondary productivity
        • it is possible to manipulate the energy transfer from producer to consumer allowing ore energy to be transferred in the food chain
        • harvesting animals just before adulthood prevents loss of energy through growth
        • steroids used to be used to increase growth but is now banned in the EU
        • selective breeding can be used to make animals that grow quicker produce more meat milk and eggs

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