EAR

• Ecosystem


  The dynamic complexity of plant, animal and micro-organism communities and their nonliving environment as a functional unit
• Interactions between biotic (living) and abiotic (non-living-spheres) produces ecosystems
• Ecosystems include independent relationships between organisms and their biophysical environment
• Classify Ecosystems

  • Terrestrial Ecosystems
  • Aquatic Ecosystems
• Terrestrial Ecosystems


  • Forests, Grasslands, Deserts
  • Differences revolve around amount of rainfall and temperature
• Aquatic EcosystemsDifferences revolve around: Amount of nutrients dissolved, Salinity, Depth of sunlight penetration, Average temperature
• Ecosystem Functioning


  • Low Functioning Ecosystem
  • Medium Functioning Ecosystem
  • High Functioning Ecosystem
• Low Functioning Ecosystem (Desert)

  • Location: 20° & 35° north & south of equator
  • Climate: High summer daytime temperature, Disparity in temp between day and night, Little rain >100mm/year
  • Vegetation: Almost no plant growth, Widely scatter shrubs, Water-conserving plants, Non-drought adapted ephemerals (set seed quickly when water is available)
• Medium Functioning Ecosystem (Temperate Grassland)

  • Climate: Unpredictable rainfall, Fires occur
  • Vegetation: Dominated by grass and annuals (plants that complete their life cycle & set seed within a growing season)
  • Human Impact: Exploited for grazing sheep & cattle
• High Functioning Ecosystem (Tropical Rainforest)

  • Climate: Warm & humid, Frequent rain, Avg temp 25℃, No true season
  • Location: No change in day length
  • Vegetation: closed canopy, Growth all year, Great diversity, Many epiphytes (plants growing on other plants), Litter leaf litter
• Ecosphere


  Collection of all living and dead organisms interacting with one another & their non-living environment
• Levels of Organisation


  • Ecosphere
  • Ecosystem
  • Community
  • Population
  • Organism
  • Habitat
• Organisms


  • Producers: plants
  • Consumers: most animals
  • Decomposers: worms, fungi & bacteria
• Decomposers


  Organisms that break down dead/decaying organisms to recycle nutrients and energy sources so producers can use that energy to start the cycle again
• Producers


  Produce energy, Make their own food through photosynthesis
• Consumers


  • Primary, secondary tertiary groups in food chains
  • Herbivores: Feed on plants
  • Omnivores: Eat everything
  • Carnivores: Eat meat
• Trophic levels


  Position of an organism in the food chain
• Arrows in food chains represent the transfer of energy
• Trophic Levels


  • Producers (plants)
  • Primary Consumers (herbivores)
  • Secondary Consumers (carnivores)
• Productivity of Ecosystems

  Amount of biomass/square m of land

  Mass of new living matter

  Both depend on available energy & nutrients & efficiency of particular elements of food chain in transporting the energy
• Cycles present in all ecosystems

  • carbon
  • nitrogen
  • water
  • oxygen
  • phosphorus
• Importance of carbon cycle to ecosystem functioning

  Energy Transfer

  Photosynthesis & Respiration

  Structural Components (carbohydrates, fats, proteins)

  Energy source for all organisms

  Regulation of Earth's Climate through sequestering carbon
• Importance of nutrient cycles to ecosystem functioning


  Nutrient Availability

  Plant Growth

  Energy transfer continuous supply of nutrients within ecosystem<|>Essential for growth & development of all living organisms<|>Conversion of atmospheric nitrogen gas into forms that plants can uptake
• Factors Affecting the functioning of ecosystems

  • Atmosphere
  • Hydrosphere
  • Lithosphere
  • Biosphere
• Atmosphere


  • Temperature and rainfall determine nature and speed of elements functioning
  • Source of: nitrogen, carbon, oxygen & water
• Lithosphere


  • Landforms determine nature/composition of soils
  • Habitat for decomposers
  • Ability to Store nutrients and water for plant life
  • Climatic factors affect soils
• Biosphere


  • Environmental conditions allow chemical changes to occur necessary for life
  • Autotrophs: producers, Heterotrophs: consumers & producers
• Vulnerability


  How sensitive an ecosystem is to change
• Resilience


  How well and fast an ecosystem can recover
• Ecosystems exist in a state of dynamic equilibrium, constantly changing while maintaining balance
• Factors that determine the vulnerability of ecosystems

  • Biodiversity
  • Extent (size and shape)
  • Location
  • Linkages
• Vulnerability of Ecosystems

  • Less variety of species/genes/habitats = more vulnerable
  • Small area = more vulnerable
  • More specialised the population of organisms is to its locations = more vulnerable
  • Low-level interdependence: the more species rely on each other to survive = more vulnerable
• Resilience of Ecosystems

  • Persistence: Ability to resist changes
  • Constancy: Ability to maintain population numbers/size
  • Resilience: Ability to adapt to changes & restore equilibrium after stress/change
• Resilience Phase

  • Elasticity: Rate of recovery
  • Malleability: Difference between final recovery level & level of the press-stress period
  • Amplitude: Threshold level of change that prevents recovery to original state
  • Succession: Stages of reconstruction after a stress
• Process of Ecological Succession

  1. Area with no life

  2. Community of organisms colonise the area

  3. First plants grow: colonisers -lichens/mosses

  4. Small shrubs

  5. Larger shrubs

  6. Animals

  7. Stable (climax) community
• Natural changes occur over extended periods allowing ecosystems to gradually change to suit changing conditions
• Impact of Fire


  • Populations & communities suffer from a reduction in biodiversity (particularly animals), but will slowly return to the area as vegetation cover returns
• Impact of Drought

  • Plants will die due to lack of water, and animals will either starve or migrate to other areas. As a result, populations of animals and plants will decline drastically. Communities will have a great decline in biodiversity
• Catergories of StressCategories

  • Immediate / Drastic Change
  • Gradual
• Major human threats to biodiversity

  • Species Intro
  • Disrupts energy flows
  • Habitat Destruction
  • Hunting
  • Exploitation via trade
  • Pollution