distribution of organisms

• abiotic factors are non living - light intensity , moisture , ph , temperature
• biotic factors are living - competition , grazing , predation, disease
• quadrats - place randomly to make sample representive

  - repeat randomly for reliability

  - identify organisms
• pitfall traps - cup level with ground

  - make drainage holes

  - cover with leaves

  - repeat and check regularly
• indicator species tell us pollution levels by their presence or absense