B6.1.2 Flashcards
What are the steps for the capture recapture technique
- Capture organisms from a sample area
- Mark organisms then release back into the environment
- At a later date recapture organisms in the original sample area
- Record number of marked and unmarked individuals
Formula for estimated population size
Estimated pop size = first sample size x second sample size/ number of recaptured marked individuals
How can you sample plants
Using a quadrat
What is a quadrat
A quadrat is a frame divided into grids. You place it on the ground and record the type and number of organisms within each sector.
What do you do with the data
You work out the mean and multiply it by the total area size to get total population
How can you make this random sampling
You can make it random sampling by marking out a grid on the sample area. Then using a random number generator to choose the coordinates to place it in a quadrat.
What is non-random sampling used for
When using transects it’s to show how the distribution of organisms change over a distance.