5.14—Core Practical 11 - habitat ecology study

Use sampling when a habitat is too large or complex to census. Random sampling estimates abundance without choosing attractive sites; systematic sampling at fixed intervals, often along a transect, tests how distribution changes across a gradient.

Use quadrats for sessile organisms and record presence, frequency, abundance or percentage cover. Match quadrat size and number to the organism and habitat, and repeat enough sites to estimate variation.

To test whether plant cover changes away from a river, place a transect across the gradient and use quadrats at fixed distances. In a uniform meadow, random coordinates reduce selection bias.

A large sample is not automatically representative. State the target population, sampling frame, measurement and possible bias before generalising.