4.3 Quadrates Samples

For this example, the habitat is sandunes:
The sample has to be:
- Random - so it is not biased
- Representative - have to take a sample large enough that the estimated population is as close to the true population as possible.

How to do this:
1) Set up a grid system across the field which will work like the x, y co-ordinates of a graph. The grid has to be equal sizes.
2) Place the quadrates into the squares. Using random numbers. (The random number generates a number for the x co-ordinate and the y co-ordinate
3) Count the number of daises in that square

Representative Sample
- the bigger the better.
- Around 10 quadrates / 10% actual area
- Draw a table with two columns consisting of Quadrate and Number of Daises
- Add up the column: number of daises
- Divide by the number of quadrates
= this will give us the number of daises per m-squared

Using this technique we can estimate the population of daises in the field and also use this technique to compare the number of daises in two or more different areas.

4.2 Quadrates

Sand-dune Ecosystem - it is made up of a number of populations which form the community and the habitat

The fence line running in the middle splits the sand-dune area into: GRAZED and UN-GRAZED by cattle. Therefore, there are two different areas within an ecosystem.

How to study the populations in the different sides: Count the number of individuals in the population.

Quadrating - when you separate land into squares using metal, wood and string (From 0.25m x 0.25m up to 1m x 1m)

It is used to sample the area and count the number of individuals inside the grid. This will be repeated a number of times = Estimate of the population size

"Quadates are a method of sampling different locations so that populations can be compared in the two different locations"

4.1 Ecosystems

Ecosystem: 

Community of organisms:

It is made up of population of difference species and they are interacting.

Population: Number of individuals of a particular species

Species: Organisms that reproduce to give fertile offspring

Habitat (Abiotic - non biological factors):
1. Daylight / Dark
2. Temperature
3. Rainfall
4. Humidity
5. Slope of the land

All of these factors are non biological factors.


- the common interaction is feeding


"A ecosystem is a community of organisms in a particular habitat. Community is made up of different populations of the different species interacting within that habitat"