We can sample the population in an area using Quadrates Sampling. Sample has to be random (so no bias introduce), and has to be representative, so we have to take a sample large enough that the estimate of the population is closer the the true population of the area.
How to make a quadrate sample?
1.Set up a grid across the area you want to sample
2.Select random numbers that gives the x,y coordinate to know where to place your quadrates
3.Calculate the area of your quadrate and then count the number of organisms in it
We need a representative sample - the bigger the better, we should be looking at 10 quadrates/ 10% of the actual area
Then, make a table with Quadrate and Number of Organism
Add up the organism/the Number of Quadrates = Number of Orgaisms per meter^2
We can use this data to compare the number of populations between two different areas.