Ecosystems

1. Ecosystems

2. Introduction • Species (be…specific!) • Bear: not good • American Black bear: great • Ursus americanus: amazing • Population • Community • Ecosystem • Habitat • Niche

3. All ecosystems have two sets of components. • Biotic • Living things • How they interact • Relationships • Abiotic • Light • Temperature • Soil • Turbidity • Wind speed • Dissolved oxygen • Slope • Salinity • Flow rate • Elevation • pH • Wave action

4. How do you measure biotic components? • Identify the species • Use a dichotomous key • Estimate the abundance of organisms • Percent cover • Percent frequency • Estimating biomass • The mass of living material • It’s easiest for plants, but it’s destructive

5. How do you measure biotic components? • We focused mostly on plants. • Animals are harder to measure, why? • There are some simple ways for smaller organisms. • For larger organisms, the Lincoln Index is the easiest way.

6. Lincoln Index • Scientists capture a sample of individuals, mark them, and release them. • Scientists then return, capture another sample, and estimate the total population

7. Calculating Lincoln Index • 25 birds caught, tagged, released. 30 birds caught second time, 18 were marked.

8. Calculating Lincoln Index • 8 elephants caught, tagged, released. 9 elephants caught second time, 6 were tagged.

9. Calculating Lincoln Index • 200 ants caught, marked, released. 185 ants caught second time, 57 were marked.

10. Calculating Lincoln Index • 20 blugill caught, tagged, released. 30 bluegill caught second time, 3 were marked.

11. Lincoln Index Assumptions • Population must be closed, no immigration or emigration • Time between samples must be small compared to the lifespan • Marked organisms must mix with the population after marking

12. Lincoln Index Setbacks • Capture can injure animal • Mark/tag may harm animal • Mark/tag may be removed • Mark/tag may increase/decrease predators • Different individuals are more/less “capturable” • Individuals may become trap-happy or trap-shy

13. But it’s not just about HOW MANY living things are in an area. • Diversity is very important as well and is a measure of the health of an ecosystem. • The lower the diversity, the lower the health. • Why do you think this is?

14. Simpson’s Diversity Index

15. Ecosystem 1 • 15 rats • 13 squirrels • 8 moles • 6 mice • 5 chipmunks

16. Ecosystem 2 • 0 rats • 10 squirrels • 3 moles • 4 mice • 25 chipmunks

17. Ecosystem 3 • 16 rats • 0 squirrels • 7 moles • 0 mice • 32 chipmunks

18. Ecosystem 4 • 3 rats • 24 squirrels • 2 moles • 4 mice • 5 chipmunks

19. Ecosystem 5 • 10 rats • 10 squirrels • 7 moles • 9 mice • 0 chipmunks

20. Ecosystem 6 • 85 rats • 0 squirrels • 0 moles • 0 mice • 0 chipmunks

21. Ecosystem 7 • 3 rats • 13 squirrels • 0 moles • 0 mice • 5 chipmunks

22. Ecosystem 8 • 0 rats • 13 squirrels • 0 moles • 0 mice • 22 chipmunks

23. Ecosystem 9 • 15 rats • 15 squirrels • 15 moles • 0 mice • 9 chipmunks

24. Gross Primary Productivity • The amount of energy produced or amount of mass produced by producers

25. Net Primary Productivity • The amount of energy or mass that is stored by producers • The amount of energy available to consumers

26. Gross Secondary Productivity • The total amount of energy consumed by consumers

27. Net Secondary Productivity • The total amount of mass gained by (primary) consumers

31. Pyramid of Numbers • Shows the number of organisms at each level. • Good for comparing changes • Bad because numbers can be too great to represent and difficult for organisms at multiple trophic levels

33. Pyramid of Biomass • Shows the amount of biomass at each level • Difficult to measure biomass, biomass varies over seasons

34. Pyramid of Productivity • Shows the amount of energy flow through an ecosystem (rule of 10 - each level is about 10% of the previous level) • Good because ecosystems can be compared • Bad because the data is hard to get and species can be at multiple trophic levels.

35. Measuring abiotic components • Marine Ecosystems: • Salinity • pH • Temperature • Dissolved Oxygen • Wave Action

36. Measuring abiotic components • Freshwater ecosystems • Turbidity • Flow Velocity • pH • Temperature • Dissolved Oxygen

37. Measuring abiotic components • Terrestrial ecosystems • Temperature • Light intensity • Wind speed • Slope • Soil moisture • Mineral content

38. Measuring abiotic components • Best method: • Count the organisms • Next best method: • Capture-Mark-Release-Recapture • (Lincoln Index)

39. Population Curves • S Curve • Reaches carrying capacity and stabilizes • J Curve • Unchecked population growth

40. Survivorship • r- strategists • Short generation time • Mature quickly • Small size • Many offspring • Little parental care • Adapted to unstable/ unpredictable environments

41. Survivorship • K- stragetists • Long life/generation time • Mature slowly • Large size • Few offspring • Parental care • Predictable/stable environments where population stays near carrying capacity

42. Population Regulation • Density dependent inhibition • Population is regulated by negative feedback • Crowding • Competition

43. Population Regulation • Density independent inhibition • Weather • Disturbances

44. Succession • A natural increase in the complexity of the structure and species composition over time • A lifeless area becomes an ecosystem

45. Bare surface • A lifeless abiotic environment becomes available for pioneer species • Usually r-selected species

46. Seral Stage 1 • Simple soil starts • Pioneer species adapted to extreme conditions colonize

47. Seral Stage 2 • Species diversity increases • Organic material and nutrients in soil increases

48. Seral Stage 3 • Larger plants colonize • K-selected species become established • r-selected species unable to compete get fazed out

49. Seral Stage 4 • Fewer new species • Narrower niches develop, K-selected species become specialists

50. Climax Community • Stable and self-perpetuating ecosystem • Maximum development under temperature, light, precipitation conditions.