CW 22-Mar-22 Ecology and Ecosystems 3 LO: To understand the use of quadrats in sampling. Starter: Is this food web complete? Is this data clearly presented? RECAP Keywords & Definitions Ecosystem – Population – Interdependence – RECAP Keywords & Definitions Ecosystem – The living and non-living things in a particular area Population – The number of individuals of a particular species Interdependence – The idea that all organisms rely on each other to survive in an ecosystem. NEW Keywords & Definitions Sample– Unbiased – Adaptation – Community – Niche – Estimate– Abundance– Distribution– Keywords & Definitions Representative sample– small area reflecting the whole Unbiased – not chosen to be more or less populated Adaptation – characteristic that gives fitness Community – the organisms in one area Niche – a particular part of a habitat for a species Estimate– an approximation, eg of the population size Abundance– how many there are, eg % cover of a plant (not the same as the number of plants- too hard to see!) Distribution– where the organisms are, eg evenly distributed, patchy, irregular… We’d like to know everything… It would take too long to learn everything… and we’d destroy it! A scientific study takes samples to get a valid estimate of the habitat, or at least some aspects of it. Scientists use standard methods 3,000kJ A quadrat is a simple square of fixed area used to take a SAMPLE of a habitat/ ecosystem. There must be MULTIPLE samples, distributed in a VALID way. Eg at random, if the distribution of organisms is also random. On the left the survey is parallel to the waterline- a randomised investigation can be done. An evenly distributed community can be surveyed by this sort of random sampling method. A few quadrats are selected at random coordinates. The data is used to CALCULATE the total population. If the distribution of plants is not random, perhaps because there is a gradient in a nonliving factor, then we do a TRANSECT (line transect) instead- we’ll do this next lesson. The samples are taken at regular intervals. Some individual plants will cross the boundaries of the sample area. You could count on the EAST and SOUTH, but not the N or W. Data table for a grid quadrat Quadrat CoCount ordinates grass Count daisy Count dandelion Count plantain Count other Count bare soil 1 2 3 4 5 Here is one kind of table for collecting data. It could be used with a quadrat that doesn’t have small squares in it, so you have to estimate the % cover by eye. This takes practice! You can do this with a friend, and record the mean value of your estimates. Data table for open quadrat Quadrat Co% grass ordinates % daisy % dandelion % plantain % other % bare soil 1 2 3 4 5 Here’s another kind of table for collecting data. It could be used with a quadrat that doesn’t have small squares in it, so you have to estimate the % cover by eye. This takes practice! You can do this with a friend, and record the mean value of your estimates. Additional facts about quadrats Calculate the population of each species in 100m2 Average cover of grass in one quadrat = n Area of one quadrat (grid) = 0.5 x 0.5 = 0.25m2 Cover of grass in each sq m = 4 x n Cover in 100m2 = 100 x 4 x n Repeat calculation for your remaining species types. Evaluate your findings! Discuss the whole activity- what do you learn about your study habitat, and what questions remain? RECAP Keywords & Definitions Sample– Unbiased – Adaptation – Community – Niche – Estimate– Abundance– Distribution– POSTSCRIPT: Bee good