Quadrats Investigating Abundance

Question 1

What is a belt transect ? (3)

Answer 1

• A belt transect is a technique used when there is gradual change from one habitat to another.
• Quadrats are placed along a line end on end allowing a strip of the ground and the species growing on it to be sampled.
• As the transect progresses from one end to another the numbers of certain species will decrease whilst others will increase

Question 2

What is sampling ? (4)

Answer 2

• When a small sample of the area is investigated in order to investigate several subsections within the habitat to give an overall picture, this is called sampling
• this uses Quadrats which give an area of 1m2
• Sampling produces reliable results by using as large a sample as possible
• Sampling is representative of the area by randomly placing Quadrats over the whole area. This is done by diving the habitat into a grid and using random numbers to generate coordinates to find the location of each Quadrat

Question 3

What is often used when investigating plant distribution and how ?

Answer 3

• Percentage cover
• This is the percentage of the Quadrat covered by a particular type of plant
• when the data for all the Quadrats is collected, the values for each species can be averaged to give an overall estimate of the percentage cover

Question 4

How else is an estimate of the total number of a plant species present in a habitat calculated? (3)

Answer 4

• Where individual plants can be easily identified, percentage cover is not necessary but the plants can be counted
• the data can be averaged
• The area of the Quadrat can be used to estimate the average number of plants per square metre, which in turn, if multiplied by the total area of the quadrats , can give an estimate of the total number of that plant species present in the habitat

Question 5

Calculations of average density and population

Answer 5

• Calculate average of each plant type

- multiply the average values by the area squared