1. Ecosystem Ecology

2. Basic ecosystem - nutrient cycling in red, energy flow in grey

3. Basic Energy Flow

6. Energy Flow Expanded

7. Energy Flow in Different Ecosystems

8. Transfer Efficiency

9. 10% Rule for Transfer Efficiency

10. Consumption Efficiency CE = food ingested/food produced How much of prey population that consumer eats For herbivores – 5% in forests, 25% in grasslands, 50% in phytoplankton ecosystems For vertebrate predators – up to 50-100% vertebrate prey; 5% invertebrate prey For invertebrate predators – 25% invertebrate prey

11. Assimilation Efficiency AE = food assimilated/food ingested How much of prey eaten is digested AE usually low for herbivores, microbivores, detritivores – 20-50% AE usually high for carnivores – 80%

12. Production Efficiency PE = new biomass produced/food assimilated How much of prey digested is converted to consumer biomass and used in reproduction – rest is lost as respiratory heat PE high for invertebrates – 30-40% Intermediate for ectotherm vertebrates – 10- 20% Low for endotherm vertebrates – 1-2%

13. For Example – Caterpillar Efficiency

14. Efficiency of Energy Transfer (Production Efficiency) E = P/(P + R) where E = efficiency P = net production R = respiration Some representative efficiency values are as follows: birds 1.3% small mammals 1.5% large mammals 3.1% fish 10.0% herbivorous insects 39% carnivorous insects 56% detritivore insects 47%

15. Lindeman’s Efficiency LE = assimilation at trophic level n assimilation at trophic level n – 1 LE examines efficiency of transfer between trophic levels – often assumed to be 10% but…is actually more complex

16. Light Absorption

17. Lindeman’s Efficiencies

18. Decomposition

19. Role in ecosystems – decomposition is gradual disintegration of dead organic matter and is brought about by both physical and biological agents decomposers - organisms which convert organic elements to inorganic form - mostly bacteria and fungi detritivores - animals that consume dead organic matter only decomposers can break down complex organic material releasing nutrients to soil - other organisms can do limited breakdown, but not enough to efficiently recycle nutrients

20. Resources for decomposers and detritivores not just dead bodies of plants and animals, but also shed dead body parts such as skin cells (food for mites on humans), feathers, horns, leaves, twigs loss of cells from root caps creates rhizosphere which is resource rich place for soil bacteria plant tissues are leaky and release soluble sugars and nitrogen compounds on leaf surface creating rich environment for bacteria and fungi on leaves called phyllosphere

21. Rhizosphere

22. Bacterial Cells in White, Green, Red

23. Phyllosphere

25. Phyllosphere – Bacteria from Leaf Impressions on Plate

26. Donor Control Decomposers and detritivores live in world where resource supply is donor controlled - the donor controls density (population size) of the recipient, but the reverse does not happen - there is no direct feedback between consumer population and resource In contrast, plants and predators do exert a direct effect on their resources because they reduce amount of resources (population size of the prey) in the environment

27. Basic Energy Flow

28. Important Terms for Decomposition Cycle Immobilization - inorganic nutrient element is incorporated into organic form, usually through the growth of green plants - thus not available to other plants Mineralization - conversion of elements from organic to inorganic form by decomposition

30. Decomposition of Leaves

32. Decomposers And Detritivores

33. Detritivore Microfauna Nematodes Rotifers

34. Detritivore Mesofauna Mites Springtails

35. Macro-fauna - African dung beetle

37. Otzi the Iceman

38. African white-backed vulture

39. African vultures – Masai Mara

40. Burying Beetles

42. Earthworms

43. Earthworm casts recycle organic matter in soil

44. Nightcrawlers are new to North America

48. Composting

49. Compost Pile Food Web

50. Soil Food Web Microbes