ecosystem and material cycles

• ecosystem - interaction between living organisms and the enviroment
• community - two or more populations of organisms
• population - all the organisms of the same species living in an area
• abiotic - non living
• biotic - living
• intraspecific - between members of the same species
• interspecific - between members of different species
• interdependance - organisms depend on each other for survival
• parasitism - a parasite will live in or on an organism and take what it needs but the host receives nothing in return
• mutualism - both species benifit
• random sampling - quadrat

  • split a field into 1 m cubes
  • using a random number generator pick a sample of squares ( eg - 10 )
  • place the quadrat around the square and count the number of organisms inside
  • repeat at each square and use your data to find a mean
• belt transect

  • place a quadrat along a line at equal intervals
  • count the number of organisms inside the quadrat
  • notice the distribution of the organism along the line
• biodiversity

  • how many different species live in an ecosystem
  • deforestation - removes habitats and decreases biodiversity
• Eutrophication

  • agro chemicals run off into rivers and lakes
  • causes surface plants such as algae to grow rapidly
  • blocks out sunlight
  • plants on the sea bed can't photosynthesise so they die
  • since the plants die there is no oxygen being produced so the fish and wildlife also die
• managing biodiversity

  • protect endangered species
  • develop natural parks
  • reforestation - plant trees
• food security - the availability of food required to support people in a defined area
• food security is reduced by

  • new pests and pathogens
  • droughts / floods - effects of global warming
• intensive farming - using machines and fertilisers to maximise crop yield

  • release CO2
  • may cause eutrophication
• sustainable fisheries - maintain fish stocks for current need and for future generations

  • humans have over-fished oceans causing low numbers of certain species with risk of extinction
  • fishing quotas - limit the amount of fish of a specific species that can be caught and killed
  • increases the size of gaps in nets - lets out juvenile fish so they can breed and increase fish numbers
• desalinisation - obtaining fresh water from sea water
• carbon cycle

  • fossil fuels - combustion - CO2 in the air
  • plants - photosynthesis - take in CO2
  • animals - waste / decay - releases CO2
  • carbon stored as fats / carbohydrates / proteins inside living things
• nitrogen cycle

  • decomposers - break down dead plants / animals - add nitrates to the soil
  • plants - absorb nitrates from the soil
  • animals - eat plants (which contain nitrates) to make proteins for growth
• forms of nitrogen

  • unreactive nitrogen gas in the air
  • nitrates in the soil
  • nitrogen in protein / DNA
  • nitrogen in animal waste
• leguminous plants - peas / beans / clover

  • root nodules - nitrogen fixing bacteria which converts nitrogen gas into nitrates which plants can use instead of fertiliser
• types of bacteria in nitrogen cycle

  • nitrifying - convert ammonia into nitrates
  • nitrogen fixing - convert nitrogen gas into nitrates
  • denitrifying - breaks down nitrates into nitrogen gas and release it into the atmosphere
• water cycle

  • heavy precipitation
  • ends up in river / lakes
  • energy from the sun evaporates the water
  • cools
  • condenses
  • form clouds
  • repeats