1. 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.

2. 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

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

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

5. 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.

6. Biosphere

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. Environmental Factors

11. 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

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

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

14. Abiotic factors in a woodland

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

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

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

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

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

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

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

22. Energy Flow

23. What is an ecosystem?
a community of living organisms interacting with one another and their non-living environment within a particular area, e.g. woodland, etc.

24. 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

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

26. 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.

27. Energy flow in the ecosystem

28. 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.

29. 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

30. Grazing Food Chains

31. 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

32. Detritus Food Chain

33. 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.

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

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

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

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

39. Consumers
Consumers are 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

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

41. 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.

42. Trophic levels

43. 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

44. Pyramid of Numbers

45. To construct a pyramid of numbers
Count the primary producers and place them at the base of the pyramid
Count each consumer and include them according to their status (primary or secondary consumer) in the pyramid
The apex of the pyramid should include tertiary or top carnivores
Draw the pyramid so that the area/volume of each level is proportional to the number of organisms found

46. Use of Pyramid of Numbers
Ecological pyramids are used to compare different communities of the ecosystem by comparing trophic levels
They attempt to discover and show the energy structure of an ecosystem as a chart by counting the number of individuals at each trophic level

47. Pyramid of Numbers In general:
The number of organisms declines as you go up the pyramid
This is due to the large energy loss (about 90%) between each trophic level
As a result there is less energy available to organisms higher up the pyramid
Loss of energy and body size increase as you go up the pyramid

48. Energy Transfer
This is the flow of energy into the ecosystem from the sun; and within the ecosystem through the different trophic levels along food chains, and finally out of the ecosystem into the atmosphere as heat loss due to respiration.

49. Energy transfer through an ecosystem

50. Energy Loss in a Food Chain

51. Energy loss in a Food Chain or Ecosystem
From the previous slide we can see that only about 10% of the energy in an organism is transferred when one member of a food chain is eaten by the next
The large energy loss from one trophic level to the next explains why food chains contain no more than four or five levels
Each trophic level contains less energy than the previous one

52. Normal Pyramid of Numbers
A reminder of what a pyramid of numbers looks like

53. Limitations of use
The size of organisms is not considered in a pyramid of numbers.
e.g. one rose bush can support thousands of greenfly.

54. A distorted Pyramid of Numbers
A similar problem arises with parasites – numerous parasites on one host – resulting in a distorted pyramid

55. An inverted Pyramid of Numbers
When organism size is not considered very unusual pyramid shapes are likely to occur.

56. Another example

57. Last example

58. Niche

59. Simple Definition
A niche is the functional role of an organism in an ecosystem.

60. Explanation of Niche
A niche is a term describing the relational position of a species or population in an ecosystem.

61. 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).

62. 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.

63. 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.

64. 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

65. 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.

66. 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.

67. Nutrient Recycling

68. Nutrient Recycling (1/3)
There is a limited amount of nutrients on earth e.g. you are probably aware of the water cycle – where water is constantly being recycled in nature. There are similar cycles for all nutrients.
When plants and animals die, their nutrient content is not wasted.
Bacteria and fungi decompose the remains and release the nutrients back into the abiotic environment (i.e. into the soil, nearby water and air).

69. Nutrient Recycling (2/3)
These nutrients are then taken up by other plants and used to make new organic material.
This material is passed on down the food chains and is reused by all the chain members.
When death occurs for these members, the nutrients are again returned to the abiotic environment and the cycling of nutrients continues in this circular way.

70. Recycling nutrients within an ecosystem

71. Nutrient Recycling (3/3)
This ensures that there is no real longterm drain on the Earth’s nutrients, despite millions of years of plant and animal activity.

72. In summary
Nutrient recycling is the way in which elements are continuously being broken down and/or exchanged for reuse between the living and non-living components of an ecosystem.

73. Carbon Cycle
Carbon forms part of all organic nutrients – carbohydrates, fats and proteins.
Carbon dioxide is removed from the environment by photosynthesis in plants, and under certain conditions, over long periods of time, some of these plants may form fossil fuels such as coal, oil, peat and natural gas.

74. Carbon Cycle Carbon dioxide is returned to the environment by:
Respiration in plants, animals & micro-organisms.
Decay caused by micro-organisms.
Combustion i.e. burning fossil fuels

75. The Carbon Cycle (1/3)

76. Summary of Carbon Cycle
Click on the link below to see a summsry of the Carbon Cycle
The Carbon Cycle
For Animated Cycle click here
Flash
Shochwave
Click on this link to go to the next slide

77. The Nitrogen Cycle
All organisms need nitrogen for protein, DNA & RNA manufacture
78% of the Earth’s atmosphere is nitrogen gas, but it cannot be used in this form by plants and animals.
Nitrogen gas must first be ‘fixed’, i.e. changed to a suitable form (ammonia or nitrate) before it can be used.

78. Nitrogen Fixation
Nitrogen-fixing bacteria in the soil convert N2 gas in the air into ammonia (NH3). This accounts for the majority of all N2 fixation.
Lightening storms and fuel burning in car engines produce nitrates, which are washed by rain into the soil water.
Nitrates are absorbed by plant roots and converted to plant protein.

79. The Nitrogen Cycle
Plant proteins are passed along food chains to become animal protein.
When organisms die, their proteins are converted to ammonia by bacterial decomposition.
Nitrifying bacteria in the soil convert ammonia (NH3) into nitrites (NO22 _) then into nitrates (NO3_).
Nitrates can be absorbed by other plants to continue the cycle.

80. The Nitrogen Cycle
Denitrifying bacteria convert soil nitrates into N2 gas.
This is a loss of N2 from the cycle.
Only happens in anaerobic conditions (when O2 levels are low) – due to flooding or accumulation of sewage.
Nitrate also enters the cycle through the addition of nitrogen rich fertilisers to the soil – made industrially from nitrogen gas.

81. The Nitrogen Cycle

82. Summary of Nitrogen Cycle
Click on the link below to see a summsry of the Nitrogen Cycle
The nitrogen cycle
For Animated Cycle click here
Flash
Shochwave
Click on this link to go to the next slide

83. Summary of Nitrogen Cycle
Nitrogen in Air
Nitrite NO2
Ammonia NH3
Nitrate in Soil NO3
Plant Protein
Animal Protein 1 2 3 4 5 6 7 8
Nitrogen Fixation & Lightning
Absorbed by roots and used by plants – Assimulation
Animal feeding, digestion & assimulation
Excretion: urea  Ammonia
Death & decomposition – putrefying bacteria
Nitrification: NH3  NO2
Nitrification: NO2  NO3
Denitrification: NO3  NO2  N