Ecosystems

Ecosystems

1. Communities

   • Organisation
     • Individual
       • The smallest part of an ecosystem
     • Population
       • Individual organisms of a species
     • Community
       • Populations of different species
   • Competition
     • Animals
       • Food
       • Mates
       • Territory
     • Plants
       • Water
       • Mineral ions
         • From the soil
       • Light
       • Space
   • Species interdependence
     • Food
     • Pollination
     • Seed dispersal
     • Shelter
   • Stability
     • Environmental factors balanced
     • Species balanced
     • Population sizes are constant

2. Trophic Levels

   • Food chains
     • Show the feeding relationships in a community
     • Prey
     • Predator
     • Apex predators
       • Top of the food chain
     • Decomposers
       • Responsible for recycling organic matter
       • The final stop of all food chains
   • 1) Producers
     • Use photosynthesis to make own food
     • Green plants and Algae
   • 2) Primary Consumers
     • Herbivores that eat producers
   • 3) Secondary consumers
     • Carnivores that eat herbivores
   • 4) Tertiary consumers
     • Carnivores that eat carnivores

3. Material Cycles

   • Nitrogen
     • Plants absorb nitrates through their roots to grow
       • Can also absorb nitrogen from the air
       • Using root nodule bacteria
     • Farmers may add NPK fertilisers to the soil, which plants can absorb
       • They may also use plants with root nodule bacteria to add nitrates back into infertile soil
         • Crop rotation
     • The nitrogen is passed-on to animals that eat the plants.
     • When plants and animals die, bacteria recycle nitrogen back into the soil through decomposition.
     • When lighting strikes soil, nitrogen is released back into the air.
   • Carbon
     • Carbon is removed from the atmosphere by producers who use it in photosynthesis.
     • Animals obtain carbon compounds by consuming plant matter
     • Respiration returns carbon (dioxide) back into the atmosphere
     • When animals and plants die, decomposers return the carbon locked in their bodies back to the atmosphere via decay.
     • Combustion of fossil fuels is another source of carbon entry into the atmosphere.
   • Water
     • Water evaporates from the Earth’s surface, and rises up into the atmosphere.
     • The water vapour cools and condenses into rain or snow
       • Eventually returns to the Earth’s surface
         • Becomes surface runoff
         • Absorbed and ground water
     • Plants take up water through their roots.
     • We get drinking water by:
       • Filtering
       • Adding chemicals to freshwater
       • Desalinating seawater

4. Decay

5. Biomass

6. Sampling biodiversity

7. Relationships between species

   • Predator-Prey
     • Cyclic in stable conditions
     • Canada lynx and Snowshoe hare
       • Increase in hare numbers = more food for lynx
         • Lynx numbers increase
       • Increase lynx numbers = more hare predators
         • Hare numbers decrease
       • Hare numbers decrease = less food for lynx
         • Lynx numbers decrease
       • Less lynx = hare population increase
   • Mutualistic
     • Both species benefit
     • Lichen
       • Algae
       • Fungi
       • Share structure and food
   • Parasitic
     • One organism benefits
       • Receives shelter and food
     • One organism is harmed
       • Loses nutrients and may suffer illness