The Biosphere

1. The Biosphere Investigating an Ecosystem Mr G Davidson

2. Investigating an Ecosystem • Examples of ecosystems include a woodland, pond, loch, moor etc.. • An ecosystem includes all the living things, their non-living surroundings and the factors which affect their lives. • Factors in the ecosystem related to living things are called Biotic Factors. G Davidson

3. Investigating an Ecosystem • Examples of these are the amount of food, disease, the amount of grazing and hunting. • Non-living factors in the ecosystem are called Abiotic factors. • Examples of these are temperature, moisture and light. G Davidson

4. Investigating an Ecosystem • The place where an organism lives is called a habitat. • There are many habitats within an ecosystem. • E.g. in a woodland there are many layers and within these layers many different habitats such as trees, leaves (dead and alive), shrubs, bushes, soil, etc.. G Davidson

5. Using a Quadrat • We could find out exactly what is living in a particular ecosystem by collecting and counting all the organisms. • This would be difficult and would take a long time. • However, we can get some idea of the amount and kinds of living things in an ecosystem by taking a sample. G Davidson

6. Using a Quadrat • In order to sample plants (and slow moving animals) we can use a quadrat. • A quadrat marks off a small piece of ground of known area so that different plants present within this sample can be identified and counted or their area of cover estimated. • This sample gives us an idea of the number and kind of organism present in the whole area. G Davidson

7. Using a Quadrat • The quadrats we use are 0.25m2 and sub-divided into 25 smaller squares each 100cm2. • The quadrat is placed randomly on the ground. • The number of small squares containing the plant we are interested in are counted. • This is called the abundance estimate. G Davidson

8. Other sampling Techniques • Pitfall traps are used to trap small animals moving across the surface of the ground. • Sweep netting is used to catch small animals living in vegetation. • Potato traps can be used to attract small animals, particularly snails and slugs. G Davidson

9. Pitfall Trap G Davidson

10. Other sampling Techniques • Pond nets are used to catch animals living in ponds. • Tullgren funnels are used to remove tiny organisms from soil samples. • Pooters are used to capture small insects. G Davidson

11. Pond Net G Davidson

12. Tullgren Funnel G Davidson

13. Pooter G Davidson

14. Estimating Total Numbers • We can estimate the total numbers of organisms living in a certain area. • We need to calculate the area we are sampling. G Davidson

15. Estimating Total Numbers • We need to estimate numbers using the quadrat. • We then calculate an average number of organisms per quadrat. • We then work out how many quadrats fit into the specified area and multiply this number by the average number of organisms per quadrat. G Davidson

16. 15m 40m Estimating Total Numbers • Calculate the area of this field. • Length times breadth. G Davidson

17. Estimating Total Numbers • We now know the area of the field is: 15 x 40 = 600m2. • We now need to sample the field by using the quadrat , say 10 times. • The quadrat is then placed randomly in 10 different spots in the field, and the number of plants counted. • Suppose we are measuring daisies. G Davidson

18. 15m 40m Sampling Daisies The quadrats are placed randomly and the number of daisies in each are counted. G Davidson

19. Sampling Daisies • The results are collected and recorded. • We then calculate the average number of daisies per quadrat. • Add up the number of daisies column and divide by the number of sites. G Davidson

20. Sampling Daisies • In this case the total number of daisies sampled was 90. • The number of sites was 10. • Therefore the average number of daisies per site is 90 ÷ 10 = 9 daisies • We now need to work out how many quadrats fit the field. G Davidson

21. Sampling Daisies • The field is 600m2 and there are 4 quadrats to each 1m2. • Therefore, the field is 600 x 4 = 2400 quadrats. • If there are, on average 9 daisies per quadrat, this means there are 9 x 2400 = 21 600 daisies in the field. • A good estimate. G Davidson

22. Estimating Total Numbers • Here is one for you to try on your own. • This time we are estimating the number of worms in a field. • Here are the results. G Davidson

23. 25m 40m 25 m Estimating Total Numbers 50m G Davidson

24. How did you do? • Average number of worms per quadrat? • Answer – 7 worms per quadrat. • Total area of field? • Answer – (50 x 40) – (25 x 15) = 1625m2 • Total number of quadrats in field? • Answer - 1625 x 4 = 6500 quadrats • Total number of worms? • Answer – 6500 x 7 = 45 500 worms G Davidson

25. Factors Affecting Distribution • There are many different factors in an ecosystem which affect the lives of organisms. • The factors are also responsible for the distribution of the organisms, i.e. where they live. • Some of these factors – the abiotic factors – are easy to measure, e.g. light, moisture, temperature. G Davidson

26. Measuring Abiotic Factors • We can measure light using a Light meter. • Make sure you don’t cast a shadow on the meter or you will get a false reading. G Davidson

27. Measuring Abiotic Factors • We can measure moisture using a moisture meter. • Carefully push the probe vertically into the soil to a depth of approximately 4cm. G Davidson

28. Measuring Abiotic Factors • When we measure abiotic factors, we wouldn’t simply take one measurement and assume that was it. • We would take a number of measurements at different spots, and then calculate an average. • This makes our results more VALID. G Davidson

29. 1 2 3 4 5 6 7 8 9 10 Sample sites Line Transect G Davidson

30. Line Transect • In this example the light intensity would decrease as you move from site 1 to 10. • The moisture readings would increase as you move from site 1 to 10. • Therefore, the distribution of plants are different – i.e. there are likely to be more daisies at site 1 than site 10. • Likewise there are likely to be more woodlice at site 10 than at site 1. G Davidson

31. Scientist studying Distribution of Organsims G Davidson

32. Identifying Organisms • It’s all very well counting organisms or collecting organisms. • Not all of them will be familiar to us. • In order to identify unfamiliar organisms, we would use a key. • There are different kinds of key. • We will use 2 kinds. • Branching Keys • Paired statement keys. G Davidson

33. Branching Keys G Davidson

34. Branching Keys • When using a branching key you must always start at the top. • If you follow the line of the key, you will be given a choice to make. • Study your organism and make the appropriate choice. • If your organism is in the key, you should eventually finish at its name. G Davidson

35. Paired Statement Keys • Paired statement keys work in the same way as branching keys. • At each stage you are given a choice. • Make the appropriate choice and go to where you are asked to go. • Again, if the organism is present, you should end up with a name for it. G Davidson

36. Paired Statement Key • Single leaf go to 2 • Several leaflets go to 6 2. Leaf with prickles HOLLY Leaf with no prickles go to 3 3. Leaf edge with lobes go to 4 Leaf edge with no lobes go to 5 4. Lobes sharp pointed SYCAMORE Lobes rounded OAK 5. Leaf with smooth edge BEECH Leaf with serrated edge ELM 6. Leaflets in fan shape HORSE CHESTNUT Leaflets in pairs go to 7 7. Leaf edge serrated ROWAN Leaf edge plain ASH G Davidson

37. Keys • The paired statement key is more manageable as it tends not to spread itself out as much. • The branching key is more pictorial and usually easier to use. • Try building your own keys for the following organisms. (Branching and Paired Statement!) G Davidson

38. Tulip Cockle Sycamore Dandelion Giraffe Gold finch Mackerel Seaweed Spider Sea Urchin Venus Fly Trap Cockatoo G Davidson