biology quadrats Essay Example
Biology control assessment: Quadrats
It would be very hard to count all the plants in a habitat; therefore you need to take a sample. You use a quadrat to sample plants. It marks off an exact area so that the plants in that area can be counted. [1]
Advantages
quadrats are relatively simple to use affordable Disadvantages easily make errors it takes a long time
1. How are quadrats used to sample plants in grassland habitats?
Random sampling is normally carried out when the area is very large, or there is a short time available. When you are using random sampling techniques, large numbers of samples are taken from different areas from the habitat. A quadrat is used for this type of sampling. The quadrat is placed on the ground and plants inside it are counted. This is done many times at different points within the habitat to give a large number of different samples. [3]
Systematic sampling is when samples are taken at fixed intervals, usually along a line. This normally involves doing transects. Transect is where a sampling line is set up across areas. For example you might use a transect to show the changes of plant species as you moved from grassland into woodland. [4]
2. How does the size of the habitat area being sampled effect the number of times a quadrat is used?
The sample unit size depends on the size of the habitat .Small scale habitats require smaller sized samples. Large scale habitats require larger sized samples. [5]
3. How is the best size quadrat to be used for sampling chosen?
Small quadrats are much quicker to survey, but are likely to yield less reliable data than large ones. However, larger quadrats require more time to examine. A balance is therefore necessary between what is ideal and what is practical. As a general guideline, 0.5 - 1.0m2 quadrats would be better for short grassland, taller grasslands and shrubby habitats might need 2m quadrats, while quadrats of 20m2 or larger, would be needed for woodland
It would be very hard to count all the plants in a habitat; therefore you need to take a sample. You use a quadrat to sample plants. It marks off an exact area so that the plants in that area can be counted. [1]
Advantages
quadrats are relatively simple to use affordable Disadvantages easily make errors it takes a long time
1. How are quadrats used to sample plants in grassland habitats?
Random sampling is normally carried out when the area is very large, or there is a short time available. When you are using random sampling techniques, large numbers of samples are taken from different areas from the habitat. A quadrat is used for this type of sampling. The quadrat is placed on the ground and plants inside it are counted. This is done many times at different points within the habitat to give a large number of different samples. [3]
Systematic sampling is when samples are taken at fixed intervals, usually along a line. This normally involves doing transects. Transect is where a sampling line is set up across areas. For example you might use a transect to show the changes of plant species as you moved from grassland into woodland. [4]
2. How does the size of the habitat area being sampled effect the number of times a quadrat is used?
The sample unit size depends on the size of the habitat .Small scale habitats require smaller sized samples. Large scale habitats require larger sized samples. [5]
3. How is the best size quadrat to be used for sampling chosen?
Small quadrats are much quicker to survey, but are likely to yield less reliable data than large ones. However, larger quadrats require more time to examine. A balance is therefore necessary between what is ideal and what is practical. As a general guideline, 0.5 - 1.0m2 quadrats would be better for short grassland, taller grasslands and shrubby habitats might need 2m quadrats, while quadrats of 20m2 or larger, would be needed for woodland