Energy in Ecosystems

• An ecosystem in a particular area includes all the living and non living components
• What are the living parts of an ecosystem known as?

  Biotic
• What are the non-living parts of an ecosystem known as?

  Abiotic
• Radiation from the sun is the main source of energy for all living things
• Solar energy is captured and used by primary producers, such as green plants and algae, during photosynthesis to make new biomass
• Primary producers are organisms that make their own glucose
• All ecosystems are dependent on primary producers
• The process of photosynthesis transforms light energy into chemical energy held in biological molecules, which can then be used by other organisms within the community known as consumers
• Trophic levels are where energy is transferred from one organism to another in a food chain
• Trophic levels move upwards, with each consuming the organisms in the levels of below
• When organisms die, their biomass is broken down by decomposers, which put biological molecules back into the soil and release carbon dioxide and heat in the process
• When decomposition occurs, carbon dioxide and heat is released
• What is productivity?

  The rate of generation of biomass in an ecosystem
• What are the units of productivity?

  Mass per area per unit time
• What is gross primary production (GPP)?

  The total amount of chemical energy stored from light energy by plants in a given area
• What are the units of GPP?

  energy/mass per unit area per unit time
• Not all light energy from the sun is converted to chemical energy by the plants, this is because it can be reflected or transmitted through the leaf, is the wrong wavelength or hits parts of the plant that cannot photosynthesise
• What is respiratory loss?

  The amount of GPP lost to the environment as heat energy when plants respire
• The remaining chemical energy after respiratory loss is known as the net primary productivity
• What are the units of NPP?

  Units of energy per unit area/volume
• What is the calculation for NPP?

  NPP = GPP - R
• What is NPP?

  The energy available for plant growth and reproduction, which is stored in the plants biomass
• NPP is also the energy available to organisms that consume the plant
• Why is NPP important?

  It represents the energy that is available to organisms at higher trophic levels in the ecosystem
• Trophic levels describe the position of an organisms in a food chain, web or pyramid
• Trophic levels can be represented by numbers or by the name of that level
• Successive trophic levels are numbered subsequently according to how far the organism is along the food chain
• Producers (trophic level 1) are plants and algae that produce their own organic nutrients and biomass using energy from sunlight
• Primary consumers (trophic level 2) are herbivores that feed on producers
• Secondary consumers (trophic level 3) are predators that feed on primary consumers
• Tertiary consumers (trophic level 4) are predators that feed on secondary consumers
• Quaternary consumers (trophic level 5) are predators that feed on tertiary consumers
• The NPP of producers are also available to another group of organisms known as decomposers, with the two main groups being bacteria and fungi
• Decomposers break down dead plants and animal material, and in the process gain the chemical energy still stored in the material
• How do decomposers gain chemical energy?

  They secrete digestive enzymes onto the surface of the dead organism, which break down the dead matter into small soluble food molecules, which are then absorbed by the decomposers
• The process of decomposition helps to release organic nutrients back into the environment, which are essential for the growth of plants and other producers
• What is secondary production?

  The chemical energy in the biomass of producers when ingested are transferred to the consumers, where it is stored in their biomass
• Only about 10% of the chemical energy in an organisms is passed onto the next trophic level each time
• Productivity is the average/rate of production over a period of time
• The rate of primary production is known as primary productivity