B7 - ECOLOGY

• Ecology


  The study of how organisms interact in an ecosystem
• Organisms


  • Generally compete for food, water, space, CO2, light, shelter, mates
• Interdependence


  The fact that organisms can rely on each other for resources and form a community
• Abiotic factors in an ecosystem

  • Light
  • Temperature
  • Moisture
  • Soil pH
  • CO2 levels
  • O2 levels
• Biotic factors in an ecosystem

  • Food availability
  • Predators
  • Prey
  • Pathogens
  • Breeding behavior
• Using quadrats to estimate population size

  1. Sample around 10% of area

  2. Take mean

  3. Multiply up for whole area
• Transect


  Allows observing how population distribution changes over a distance
• Food chain


  Shows the direction that biomass and energy flows in an ecosystem
• Trophic levels


  • Producers
  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
  • Apex predators
• Population numbers at each trophic level fluctuate over time in an ecosystem
• All life is carbon-based, so carbon is recycled when organisms die
• CO2 is produced during decomposition and used by plants to grow
• Farmers utilize decomposition to produce natural fertilizers
• Farmers also use decomposition to produce methane gas as fuel
• Biodiversity


  The number of different types of organisms in an ecosystem
• High biodiversity generally makes for a stable ecosystem
• Human development usually results in lower biodiversity
• Carbon dioxide and methane contribute to global warming
• Water vapor is responsible for 95% of the greenhouse effect
• Deforestation reduces biodiversity and is often done to create farmland
• Water cycle


  1. Energy from the sun causes water to evaporate

  2. Water vapor accumulates in the sky and condenses into clouds

  3. Water falls back down to earth as precipitation

  4. Water seeps into soil, flows into rivers, or is taken up by plants

  5. Cycle repeats
• Carbon cycle


  1. Plants take in carbon dioxide from atmosphere and convert it into biological molecules through photosynthesis

  2. Carbon in plants can be released back to atmosphere through respiration or passed on to animals

  3. When plants and animals die, carbon can be released as carbon dioxide through microbial respiration or converted into fossil fuels

  4. Fossil fuels can be burned by humans to produce carbon dioxide
• Places where carbon is stored

  • Air (as carbon dioxide)
  • Plants (in biological molecules)
  • Soil (containing bacteria and microorganisms)
  • Fossil fuels (underground)
  • Animals (in biological molecules)
• The carbon cycle is more complex and includes more living organisms than the water cycle
• Burning of plants like burning logs in a fire or burning biofuels in an engine can also release carbon dioxide into the atmosphere
• Biodiversity


  The variety of different species on earth or within an ecosystem
• Biodiversity


  • It makes ecosystems stable
  • It provides pollinators that help pollinate plants
  • More than half of new medical drugs are derived from living organisms
• Humans damage the environment

  Reduces biodiversity and the benefits it provides
• Factors reducing biodiversity


  • Increasing human population
  • Increasing individual demand for resources and consumer goods
  • Clearing natural ecosystems to get resources
  • Pollution (waste, chemicals, greenhouse gases)
• greenhouse effect


  1. Solar radiation from the sun passes through the atmosphere and hits the earth.
  2. Some of this energy is reflected straight back towards space, while some is absorbed by the earth and then reemitted towards space.
  3. Some of the reemitted energy makes it all the way to space, but much is absorbed by small molecules called greenhouse gases. 
  4. These molecules then reemit the energy and the whole process of absorption and emission can happen over and over again. 
  5. This trapped energy keeps the atmosphere warmer and more stable than it would otherwise be. 
• Climate change is a consequence of global warming and refers to the effects on the climate, such as large-scale shifts in weather patterns
• Global warming refers to the overall increase in the earth's temperature
• • One effect of global warming is the melting of ice caps.
  • This will increase the volume of water in the ocean and could lead to seasonal flooding, or the submersion of entire islands.
  • This is made worse by the fact that water expands when it is heated, so it will also increase in volume
• Climate describes the typical weather conditions in an entire region for a very long time
• Weather refers to short term atmospheric conditions, like whether it's raining or sunny on a particular day
• It's really important that biodiversity is maintained, but other factors also have to be taken into account
• Programmes to Protect Ecosystems and Biodiversity

  1. Breeding programmes to help prevent endangered species from becoming extinct

  2. Programmes to protect and regenerate rare habitats

  3. Programmes to reintroduce hedgerows and field margins around fields

  4. Regulations and programmes to reduce deforestation and carbon dioxide emissions

  5. Encouraging recycling to reduce waste in landfill sites
• Protecting biodiversity costs money

  • Governments sometimes pay farmers a subsidy to reintroduce hedgerows and field margins
  • It can cost money to keep a watch on whether the programmes and regulations designed to maintain biodiversity are being followed
• Protecting biodiversity


  May come at a cost to local people's livelihood
• Protecting biodiversity


  May conflict with protecting food security