Distribution of organisms

• habitat-where an organism lives
• distribution of a an organism affected by environmental factos:
  • temperature
  • avalibility of water
  • avalability of oxygen & carbon dioxide
  • availability of nurtients
  • amount of light
• two ways to study distribution of an organism:
  • measure how common an organism is in two sample areas
  • study how distribution changes across an area

• used to compare how common an organism is in two sample areas
• steps:
  • choose first sample area 
  • divide area into grid
  • pick ramdom point
  • place 1m   quadrat on point
  • count organisms in quadrat
  • repeat steps in first area
  • work out mean
  • repeat all steps in second sample area
  • compare the two means

• work out mean mumber of organisms per m 
• then mulitiply mean by total area
• example- open field is 800m squared, average of 22 daisies per m 

22     800= 17600

• transect-lines
• how organsims are distributes across a line
• steps:
  • mark out line using tape measure
  • count all the organsims touching the line
  • or
  • place quadrats along the line (next to each other or at intervals)