the living world

• When drawing food webs, the arrow indicates the direction of energy transfer, with producers getting energy from sunlight and consumers getting energy from producers
• Decomposers make nutrients available to reenter the food webs
• Factors affecting ecosystems


  • Biotic factors (living)
  • Abiotic factors (non-living)
• Biomes


  • Large scale ecosystems
  • Tropical rainforests are close to the equator with high temperatures, high rainfall, low pressure, little seasonal variation, and a large number of green plants
  • Deserts are close to the tropics with dry air, subtropical high pressure, high daytime temperatures, very little cloud cover, low nighttime temperatures, and low rainfall
  • Tropical grasslands have dry and wet seasons affected by the movement of Hadley cells
  • Temperate grasslands have hot summers and cold winters
  • Mediterranean climates have hot, dry summers and mild winters
  • Deciduous forests are very rainy and have trees that shed leaves in winter
  • Coniferous forests have very cold winters, little sun, and trees that do not drop leaves
  • Polar regions have very cold air which sinks, very low temperatures, and are very dry
• Tropical rainforests


  • Very warm with little temperature variation
  • Very wet with rainy seasons
  • Different layers - top canopy, middle canopy, lower canopy
  • Infertile soil with rapid cycling of nutrients
  • Plants have shallow roots, leaves adapted to shed water, top canopy protects soil from erosion
  • Animals are specialists adapted to rainforest life
• Half of the world's rainforests is now gone, disappearing at a rate of one hectare per second
• Negative impacts of deforestation

  • Loss of biodiversity
  • Impact on climate change
  • Loss of soil protection
  • Mercury pollution of rivers
  • Loss of indigenous tribes' land
  • Loss of potential medicines
  • Loss of tourism
• Positive impacts of deforestation

  • Provides jobs and tax revenue
  • Provides land for homes, farming, and infrastructure
• Strategies to protect rainforests

  • Conservation and education by NGOs
  • Intergovernmental agreements on hardwood trade
  • Debt reduction for protecting rainforest areas
  • Increase in ecotourism
  • Selective logging
  • Replanting of felled trees