Ecology

1. Ecology

2. What is Ecology? Ecology is the study of how living things relate to each other and to their environment Their environment refers to all the conditions in which the organism lives, which affect the growth and development of the organism.

3. What is an Ecosystem? An ecosystem is a community of living organisms interacting with one another and their non-living environment within a particular area. The earth itself is a true ecosystem as no part of it is completely isolated from the rest. **Ecosystem = Communities + Environment

4. Diversity of ecosystems Woodland, Hedgerow, Seashore, Marine, Grassland, Freshwater, Tree, etc. Can you name some more? Ecosystems can be very large or very small

5. To study an ecosystem We divide the ecosystem into a number of smaller, more manageable areas (habitats). Individual habitats are then studied.

6. What is the Biosphere? The biosphere is that part of the earth inhabited by living organisms, including land, ocean and the atmosphere in which life can exist. It is the global ecosystem.

7. Relationships in the biosphere

8. What is a Habitat? A habitat is the particular place within the ecosystem where an organism lives and to which it is adapted As a living organism (you) what is your Habitat, Ecosystem and Biosphere?

9. Summary • Biosphere = that part of the earth and its atmosphere in which life can exist composed of ecosystems • Ecosystems = composed of communities of organisms and their environment • Communities = populations of different species of organisms • Habitats = is the place where an organism lives and to which it is adapted

10. Learning check • What is ecology? • What is an ecosystem? • What is the biosphere? • What is a habitat?

11. Definition of Niche A niche is the functional role of an organism in an ecosystem. A niche is a term describing the relational position of a species or population in an ecosystem.

12. Niche Explanation (cont’d) This includes how a population responds to the abundance of its resources and enemies (e.g. by growing when resources are abundant, and predators, parasites and pathogens are scarce) and how it affects those same factors (e.g. by reducing the abundance of resources through consumption and contributing to the population growth of enemies by falling prey to them).

13. Niche Explanation (cont’d) The abiotic (non-living) or physical environment is part of the niche because it influences how populations affect, and are affected by, resources and enemies. The description of a niche may include descriptions of the organism's life history, habitat, and place in the food chain.

14. Niche Explanation (cont’d) No two species can occupy the same niche in the same environment for a long time. When plants and animals are introduced into a new environment, they can occupy new niches or niches of native organisms, outcompete the native species, and become a serious pest.

15. Lichens Two lichens on a rock, in two different ecological niches. Can you explain why they are different niches? • Lichenes on a rock • Author: Johann Dréo • Date: 2005, august, 10

16. Summary For a species to maintain its population, its individuals must survive and reproduce. Certain combinations of environmental conditions are necessary for individuals of each species to tolerate the physical environment, obtain energy and nutrients, and avoid predators.

17. Summary cont’d The total requirements of a species for all resources and physical conditions determine where it can live and how abundant it can be at any one place. These requirements are termed the ecological niche.

18. Environmental Factors

19. Environmental factors that affect organisms Abiotic These are non-living factors Biotic These are living factors Climatic These are the average weather conditions that affect the community in an ecosystem Edaphic These refer to the soil

20. Abiotic factors These are the non-living features of an ecosystem (i.e. the physical and chemical conditions) that affect the community.

21. Temperature Light intensity Air speed Water current Humidity pH Dissolved oxygen Salinity Nitrate, phosphate and other plant nutrients Abiotic factors include:

22. Abiotic factors in a woodland

23. Biotic factors These are the living features of an ecosystem that affect the other members of the community.

24. Biotic factors include: • Plants for food and shelter • Predators • Prey • Parasites and pathogens • Decomposers • Competitors • Pollinators

25. Climatic factors These are elements of the climate (weather) that influence the life and distribution of the organisms that live in a particular environment.

26. Climatic factors include: • Temperature • Rainfall • Humidity • Wind • Light intensity (including seasonal variations) • Day length

27. Edaphic factors These are the physical, chemical and biological characteristics of the soil that influence the community.

28. Edaphic factors include: • Soil type, • Soil pH, • Available (soil) water, • Air and Mineral content, • Humus, • Soil texture and Structure.

29. Aquatic Environmental Factors The following are also considered as factors: • Light penetration • Currents • Wave action

30. Learning check • What is meant by abiotic factors? Give examples. • What is meant by biotic factors? Give examples. • What are edaphic factors? Give examples

31. Energy Flow Ecosystems are unable to function unless there is a constant input of energy from an external source. Where does this energy come from? The Sun

32. The Sun The sun is the primary source of energy for our planet.

33. Energy Flow is the pathway of energy transfer from one organism to the next in an ecosystem due to feeding, e.g. along a food chain Feeding allows energy to flow from one organism to another in an ecosystem.

34. Energy flow in the ecosystem

35. Food Chain Is a flow diagram that begins with a plant and shows how food/energy is passed through a series of organisms in a community. Each organism feeds on the one before it. A food chain ends when there is not enough energy to support another organism. An example of a food chain: grass rabbit  fox.

36. A Grazing food chain - is one where the initial plant is living e.g. Grass  grasshoppers  frogs  hawks Honeysuckle  aphids  ladybirds  thrushes Seaweed  winkles  crabs  herring gulls Phytoplankton  zooplankton  copepod  herring

37. Grazing Food Chains

38. A Detritus food chain - is one where the chain begins with dead organic matter and animal waste (detritus) e.g. Detritus  edible crab  seagull Fallen leaves  earthworms  blackbirds  hawks

39. Food Web This is a chart showing all the feeding connections in the habitat/ecosystem. Constructed by showing the links between all the interconnecting food chains in the habitat.

40. Food Web the interconnected food chains in an ecosystem e.g.

41. A woodland food web Construct a two food chains (4 ‘links’) from the above food web

42. Another food web What is the longest food chain you can construct from this food web?

44. Producers Producersareorganisms capable of making their own food by photosynthesis, e.g. green plants. Primary producers are the first members of a food chain

45. Consumers Consumersare organisms that feed on other organisms. They cannot make their own food. There are three types: • Primary consumers – feed on producers • Secondary consumers – feed on primary consumers • Tertiary consumers – feed on secondary consumers

46. Primary consumer Secondary consumer Tertiary consumer Producer Woodland food chain Honeysuckle  aphids  ladybirds  thrushes

47. Learning check • What is the primary source of energy? • Energy flow/transfer through an ecosystem is achieved by … • What is meant by a Grazing food chain? Give an example • Construct a simple food web Two food chains e.g. Plant  caterpillar  thrush  fox Plant  earthworm  blackbird  fox Combine them to form a food web

48. Trophic Level This refers to the position of an organism in a food chain. Plants are at the 1st trophic level (T1) and Herbivores occupy the 2nd trophic level (T2). Carnivores that eat herbivores are at the 3rd trophic level (T3). The 4th trophic level (T4) is often occupied by the top carnivore.

49. Trophic levels

50. Pyramid of Numbers A diagram that represents the numbers of organisms at each trophic level in a food chain. Bottom layer is the largest and represents a very large number of primary producers The next layer smaller and represents a smaller number of primary consumers The next layer – the no. of secondary consumers The uppermost layer where there may be only one tertiary consumer