Ecology

• Abiotic factors


  Nonliving characteristics of an ecosystem
• Abiotic factors


  • Light intensity
  • Temperature
  • Type of soil
  • Water availability
  • Salinity
  • Nutrients in the soil
  • Wind speed
  • Soil pH
• Adaptations that allow species to survive in different conditions


  • Some plants can survive high salinity by storing excess salt in their leaves which eventually drop off before the salt can reach the stem
  • Some animals like polar bears who live in cold conditions, have thick fur so that they don't freeze
• Quadrat


  A sampling area (often 1m squared) in which the number of organisms in that area is counted and recorded
• The number of organisms in a quadrat is usually considered to be representative of the total area under investigation
• Estimating abundance using quadrats

  Estimated abundance = average no. per quadrat x total area / area of quadrat
• Capture-recapture method


  1. Collect a group, tag them and release them back out into the environment

  2. Collect another group of organisms and see how many are tagged

  3. Total number = no. of animals tagged on first visit x 100 / average percentage of tagged animals per recapture
• Food chain


  A simple diagram that starts with a producer, usually a photosynthetic organism, which is eaten by a first-order consumer which is then eaten by a second-order consumer and so on
• Food web


  A number of intertwined food chains
• Trophic levels

  • Producers (first trophic level)
  • First-order consumers (usually all herbivores, second trophic level)
  • Carnivores that feed off herbivores (third trophic level)
• Not all of the energy is transferred between trophic levels. Some energy is transformed into other forms of energy such as heat
• A large mass of producers is needed to sustain a small number of top-level consumers
• Transect


  Recording all the organisms found in a narrow strip of an ecosystem
• Drawing a transect of a rock platform


  1. Stretch a rope from the waters edge to the part of the rock platform that is furthest from the water

  2. Stretch a second rope, parallel to the first and a short distance apart (50cm is a suitable distance in this instance)

  3. Travel along the rope and record all the living things that are found in the narrow strip between the ropes

  4. Use a key to indicate each type of organism found in the transect
• A transect can reveal information about characteristics that are important to a species' survival
• Finding the distribution of species and the environment the species live in can help find ways to protect the species
• Biotic factors - living things that affect ecosystems (e.g. predators)
• Abiotic factors - non-living things that affect ecosystems (e.g. temperature)
• Ecosystem - all the organisms living within an area, together with their physical environment
• Secondary consumers - animals that eat primary consumers or other secondary consumers
• Primary producers - plants that make their own food using photosynthesis
• Ecosystems have both biotic and abiotic components
• Population - all individuals of the same species living in one place at the same time
• The interactions between these components determine how well they survive
• Tertiary consumer - animal that eats secondary consumers
• Decomposers - microorganisms that break down dead organic matter into simpler substances
• Producers - plants that make food from sunlight using photosynthesis
• The biotic component includes all the living organisms present in an ecosystem.
• The abiotic component includes all the non-living parts of an ecosystem such as water, air, soil, rocks etc.
• Abiotic factors are non-living parts of the ecosystem such as temperature, light intensity, water availability, soil type, pH level, nutrient levels.
• Biotic factors are living parts of the ecosystem such as predators, prey, competitors, parasites, pathogens, mutualists, decomposers.
• Trophic pyramid shows the number of organisms at different trophic levels (producers, herbivores, carnivores) in an ecosystem.
• Primary consumers - animals that eat producers
• Decomposers break down dead organic matter into simpler substances which can be used by plants to make new cells.
• Food webs show the interconnectedness of multiple food chains in an ecosystem.
• Aquatic ecosystems include freshwater systems like lakes, rivers, and streams, and marine systems like oceans and coral reefs.
• Food chains show the transfer of energy between species within an ecosystem.
• Terrestrial ecosystems include forests, grasslands, deserts, tundras, and wetlands.
• Energy flow diagram shows how energy flows through an ecosystem from producers to consumers.
• Ecosystems can be classified based on their structure (terrestrial or aquatic) and function (producers, consumers, decomposers).