distribution of organisms

• biological keys are used to identify organisms based on their physical appearance
• quadrats are used to measure the variety and abundance of plant species in an area
• to achieve reliable results with a quadrat they must be thrown randomly and be done multiple times
• pit fall traps are used to sample the variety and abundance of invertebrates living on the soil surface
• pit fall traps should not;

  -be left to long

  -be visible to predators

  -be above the level of the soil
• biotic factors are living factors; competition for resources, disease, food availability, grazing and predation
• abiotic factors are non-living factors; light intensity, moisture, PH and temperature
• measuring light intensity;

  use - light meter

  make sure there are no shadows covering the meter, make sure readings are taken at the same time of day
• measuring soil temperature;

  use - soil thermometer

  make sure the probe is inserted to the same depth each time
• measuring soil PH;

  use - soil PH meter

  make sure to clean the probe before each use
• measuring soil moisture;

  use - moisture meter

  make sure probe is cleaned before each use
• Line transects are used to measure the distribution of an organism in an ecosystem.

  Quadrats are placed at regular intervals and abiotic factors will be measured to find out the

  relationship between abiotic factors and the relative abundance of a plant species
• factors effecting biodiversity ;

  human influence - deforestation - loss of habitat and food source

  human influence - invasive species - loss of food source

  natural disaster - earthquake - loss of habitat, food source, drop in population
• Indicator species tell us about the level of pollution in an area by their presence or absence
• invertebrates are used to indicate levels of water pollution

  stonefly nymph - low (stream)

  dragonfly nymph - low (pond)

  freshwater shrimp - slight

  hog louse - medium

  tubifex worm - high

  no life - extreme
• lichen can be used to estimate levels of air pollution;

  shrubby - low

  leafy - medium

  crusty - high