Organisms in their environment

How can we find out what lives here?

How can we find out what lives here? We can’t check the whole area We have to sample How do we sample randomly but representatively?

A quadrat Quadrats are used to investigate the size of a population of plants or any other organism that doesn’t move or moves slowly. Why couldn’t you sample quick moving organisms like flies using a quadrat? You would always test using the same size quadrat. Why?

Using a quadrat Throwing of the quadrat must be random. This avoids bias (for example if you always threw away from cow pats or towards buttercups) and makes sure the sample is representative You would do a number of random readings and find the mean number of organisms per m2 You could compare the distribution of the same organism in different habitats for example It doesn’t matter if you count part plants in your sample or not, as long as you always do the same thing.

What is the range? Range is the difference between minimum and maximum range

Mean, median and mode Mean - add up the values and divide by the number of values you have Median – put the sample in order and the median is the middle number Mode – is the most frequently occurring number

Modelling the process Randomly sample the plants and slow moving animals on this scene. Record in your book what you found Compare between groups – did we all find the same things?

To estimate a population from a sample https://www.tes.com/teaching-resource/quadrats-indoor-activity-11063881

If you were asked to make a list of everything on this page how would you go about it?

In Biology we take samples. From this we can estimate a population and assess biodiversity.

Quadrats Throw your model quadrat on the page. Record what you can see inside it. Show the totals of different species that you have observed in the habitat using a tally. You decide: Should you include objects that are not fully in the square? Should you include objects you know you have already recorded? Use drinking straws made into squares or paper with square windows cut out.

Quadrats How accurate was your survey? Write a list of everything you can see on the picture that your survey didn’t cover. Compare your results to the person next to you. Summarise the comparison in one sentence.

Quadrats- Discussion Did we all record the same things? Who found Wally? Did anyone purposely throw the quadrat to an interesting area? Did anyone study the same area twice? How do you think we can make our data more accurate and more reliable? Use drinking straws made into squares or paper with square windows cut out.

Conclusion Write a conclusion about the biodiversity of the area you have studied Do you think this method is accurate? How could you improve it? Wally is an endangered species. What does this mean? Use a real life example in your answer. How can biological surveys be used to help endangered species? Use drinking straws made into squares or paper with square windows cut out.

Wally is an endangered species Wally is an endangered species. From your survey results can you identify any other endangered species? Discuss how many of a species there must be before we classify it as endangered

Class results: If we put the results from ALL the surveys together would we have covered everything that is in the picture? Discuss how many of a species there must be before we classify it as endangered

Sampling along a transect Transects are not random You stretch a tape between two points You sample along that line at regular intervals This shows how the distribution of organisms changes along that line You can also measure physical factors along the line such as light levels or temperature.

A transect at Gibraltar point

Line transects Drop a ruler on the page Where it lands draw a 20cm line How does this compare to your initial survey?

Sampling along a real transect 10cm 20cm 30cm 40cm 50cm 60cm 70cm 80cm 90cm 1m Sample description

What did you find out? Write a short report. Your report needs to include Information about biodiversity of the school field Which organisms was the mode? Was there a change across the field (the transect)?