B2.4 - Distribution of organisms

Abiotic factors that affect organisms:

• temperature
• availablility of nutrients (magnesium, nitrates)
• amount of light
• availability of water
• availability of oxygen & carbon dioxide

Biotic factors that affect organisms:

• disease
• competition
• predators

Quantitative data can be obtained by:

Random sampling w/ quadrats

Place quadrat randomly.

Could use random coordinates.

Calculate percentage cover.

Sampling along a transect

Lay out a measuring tape.

Use the quadrat at regular intervals.

Place quadrat on line + calculate percentage cover of organism.

Same time measure abiotic factor.

repeating experiments improves the validity of results. rules out anomalies.