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Ecosystem Balance

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Chapter 6 Ecosystem Balance – PowerPoint PPT presentation

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Title: Ecosystem Balance


1
Chapter 6
  • Ecosystem Balance

2
Ecosystem Balance
  • 6.1 Relationships in the Ecosystem
  • 6.2 Ecological Succession
  • 6.3 Stability in the Ecosystem
  • 6.4 Land Biomes

3
6.1 Relationships in the Ecosystem
  • Objectives
  • Explain the relationship between the population
    sizes of predator and prey.
  • Define symbiosis and describe several symbiotic
    relationships.

4
Relationships in the Ecosystem
  • A complex web of relationships exist among all
    the species in an ecosystem.
  • Scientists study these relationships by
  • Studying how two populations interact with one
    another.
  • Expanding the knowledge they have gained to other
    parts of the ecosystem.

5
Predator and Prey
  • One of the relationships ecologists study is that
    of predator and prey.
  • Define Predator.
  • Define Prey
  • Examples

6
Predator and Prey
7
Predator and Prey
  • The sizes of predator and prey populations are
    closely linked.
  • Figure 6.1 p. 89
  • Prey experience populations cycles.
  • A predators populations cycle mimics that of its
    prey.

8
Parasitism
  • Some animals do not kill the prey they feed on.
  • Parasitism-an organism that feeds on the tissue
    or body fluids of another organism
  • Host-the organism the parasite feeds off of
  • Examples

9
Parasites-Tapeworms and Roundworms
10
Symbiosis
  • Symbiosis-a relationship in which two species
    live closely together
  • Three types
  • Parasitism-one is helped and the other is harmed
    (typically)
  • Commensalism- one organism benefits and the other
    is neither helped or harmed
  • Examples
  • Mutualism-both organism benefit
  • Examples

11
Commensalism
12
Mutualism
13
Questions
  • What is the relationship between the population
    sizes of predator and prey.
  • Define Symbiosis
  • What are some examples of symbiotic relationships?

14
6.2 Ecological Succession
15
Objectives
  • Contrast primary and secondary succession.
  • Describe the sequence of ecological succession in
    a lake and on an island.

16
Ecological Succession
  • Organisms affect their environment
  • Example Plants ? Soil
  • Changes are not always beneficial
  • Old niches are replaced by new niches.
  • Other forces can cause change in the environment.
  • Example Forest Fire

17
Ecological Succession
  • As environment change the communities living in
    that environment change as well.
  • In many cases different communities follow one
    another in a definite pattern, this is called
    succession.

18
Volcano Eruption
  • A volcano erupts leaving the land covered in bare
    black rockit is lifeless.
  • Does it stay this way?

19
Volcano Eruption (cont)
  • No
  • Almost immediately organisms begin to inhabit the
    area.

20
Primary Succession
  • Define Primary Succesion
  • Examples Cooled lava fields and exposed rock
    from retreating glaciers.

21
Primary Succession
  • Primary succession is an orderly process.
  • Follows the same general pattern in most
    ecosystems.

22
Step 1
  • Colonization by new organisms and formation of
    soil from exposed rock.
  • On land this is done by lichens.
  • Define lichens.
  • Lichens can live on bare rock.

23
Step 1 (cont)
  • Lichens secret acids that break down the rock and
    form organic material by photosynthesis.
  • Weathering also breaks down rocks.
  • Soil is formed by the actions of the lichens and
    weathering.

24
Pioneer Community
  • Lichen Community
  • First community to colonize the area.

25
Step 2
  • Once soil is formed, grasses and other small
    plants begin to grow.
  • Root growth and accumulation of dead leaves ?
    Soil formation
  • Plants grow dense ? lichen disappear

26
Grass Community
  • Survives for many generations and makes the soil
    deeper and more fertile.
  • Soil is deep enough ? Growth of nonwoody plants
    with deep roots (Heath Mat).
  • These plants are taller and shade out the
    grasses.
  • Since the grass/shrub community is not diverse a
    small disturbance may cause drastic change.

27
Pines and other tress
  • Pines or other trees with shallow roots are next.
  • Trees shade out the heath mat.

28
Broadleaf and Hardwood Trees
  • As the soil deepens even further broadleaf and
    hardwood trees take over.
  • Hardwood forest in the final stage of succession
    in many areas.

29
Climax Community
  • A community that does not undergo further
    succession.
  • Climax communities are usually highly diverse and
    can often survive even severe local disturbances.

30
Primary Succession
31
Primary Succession
  • Only occurs on freshly exposed rock or in places
    where a severe disturbance has occurred.
  • However most disturbances are not this drastic.

32
Secondary Succession
  • A fire may kill many plants but leave the soil in
    place.
  • Living things can quickly colonize these types of
    areas.
  • Define Secondary Succession.
  • Examples Storms, Fires and human activity

33
Deforestation
34
Secondary Succession
  • Secondary succession resembles the later stages
    of primary succession.
  • 1st to colonize are
  • Next to colonize
  • Final to colonize

35
Secondary Succession
  • Research has shown that many habitats never
    develop climax communities.
  • Why?
  • Example

36
Secondary Succession
37
Aquatic Succession
  • Newly formed mountain lake.
  • Low nutrient levels
  • Supports few organisms.
  • Reeds and other aquatic plants.
  • Organic matter builds up and lake fills with
    sediment.
  • Nutrient rich water
  • Increase in wildlife
  • Water plants cover the surface.
  • Lake fills with sediment ?Marsh
  • Land plants begin to colonize
  • Finally ?Fertile Meadow (possibly a forest)

38
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39
Island Succession
  • Similar to succession on the continents.
  • Any organisms found on an island must have
    ancestors that were
  • Carried by water
  • Carried by wind
  • Carried by other organisms
  • Many islands have large bird populations.

40
Island Succession
  • There are many unfilled niches on islands.
  • Organisms can evolve to fit many niches.
  • When a population of organisms adapted to their
    new niches new species are formed.
  • Example Figure 6.9 p. 95

41
Review
  1. How does primary and secondary succession differ
    from each other?
  2. What is a climax community?
  3. What is a pioneer community?
  4. Describe the sequence of ecological succession in
    a lake and on an island.

42
6.3 Stability in the Ecosystem
43
Objectives
  1. Explain the concept of ecosystem stability.
  2. Characterize the effects of disturbances on the
    ecosystem

44
Stability is a measure
  • of how easily an ecosystem is affected by a
    disturbance.
  • how quickly it returns to its original condition
    after a disturbance.
  • Conditions include biotic and abiotic factors,
    patterns of energy flow and nutrient cycling.

45
More stable ecosystem
  • Will return steady pattern of energy flow
  • Experience fewer food web changes.
  • Fewer evolutionary changes
  • Fewer changes in the abiotic environment.

46
Stability in the Ecosystem
  • Determined by the complexity of food web
  • Manages the systems energy flow and nutrient
    cycles.
  • More connectionsstability
  • Impact of disturbance is less.

47
Equilibrium
  • State of balance
  • Changes counteract other changes.
  • Weather cooling is counteracted by the
    evolutionary adaptation to cold weather.
  • Disturbed ecosystem returns to a state of
    equilibrium (balance).

48
Ecosystem Function
  • Scientist do not understand every detail of how
    even simple ecosystems function.
  • They do understand that a change in one part of
    triggers a change in another.
  • Scientists are trying to apply the chaos theory.

49
Chaos Theory
  • A type of mathematics
  • Suggests that ecosystem may be sensitive to even
    small changes
  • The beginning state of an ecosystem is crucial to
    its later development.

50
Species Extinction
  • Species are becoming extinct at an alarming rate.
  • Fastest since the extinction of dinosaurs.
  • Possible causes
  • Human Growth
  • Habitat destruction
  • Introduction of foreign species
  • Pollution of fresh water

51
Thought
  • It is difficult for scientists to predict the
    long-term effects of humans on the biosphere.
  • And for them to predict the ability of the
    biosphere to support human population.

52
Review
  • What makes an ecosystem stable?
  • What happens to a stable ecosystem when a
    disturbance occurs?
  • What happens to a ecosystem that is unstable when
    a disturbance occurs?

53
6.4 Land Biomes
54
Objectives
  • Explain the concept of the biome, and name the
    eight major land biomes.
  • Name an area in which each type is located.

55
Biomes
  • Earth is very large and diverse
  • Environments range from the ice of Antarctica to
    the heat and rain of the Amazon.
  • Difference in temperature and rainfall create a
    vast array of conditions.
  • Life has adapted to almost all of these
    conditions.

56
Biomes
  • Definition-major type of ecosystem with
    distinctive temperature, rainfall and organisms.
  • Either terrestrial or aquatic.

57
Biomes
  • Biome is the largest general category used to
    classify ecosystems
  • Conditions may vary from place to place
  • Smaller ecosystems within a biome may have
    different habitats with different conditions and
    organisms.
  • Every habitat on Earth is different.
  • Term Biome is useful when discussion related
    habitats.

58
Aquatic Biomes
  • Determined by
  • Water depth
  • Nutrients
  • Nearness to land

59
Terrestrial Biomes
  • Determined by
  • Average temperature
  • Amount of precipitation
  • 8 major types of land biomes
  • Desert
  • Tundra
  • Coniferous forest
  • Deciduous forest
  • Rain forest
  • Steppe
  • Prairie
  • Savanna

60
Desert
  • Low humidity
  • High summer temperatures
  • Low annual rainfall
  • Supports only a small amount of biomass
  • Deserts cover 25 of Earths land surface
  • Deserts contain only 1 of Earths biomass
  • Plant life is scarce in a desert due to lack of
    water

61
Desert in Australia
62
Tundra
  • Cold
  • Windy
  • Dry
  • South of polar ice caps in Alaska, Canada,
    Greenland, Iceland, Norway and Asia
  • Very little plant life due to lack of water

63
Tundra
64
Forest Biomes
  • Contains 75 of Earths Biomass
  • Three types
  • Coniferous forest- containing conifers.
  • Deciduous forest containing deciduous trees.
  • Rain forest dense canopy of evergreen, broadleaf
    trees that receives at least 200 cm of rain each
    year.

65
Deciduous Forest
66
Coniferous Forest - Yosimite
67
Amazon Rain Forest
68
Rain forest
  • Covers only 6 of Earths land surface.
  • Contains more than 50 of all Earths biomass.
  • Most diverse biome.
  • Destruction of the rain forest is a HUGE
    environmental problem

69
Grasslands
  • Cover 22 of Earths land surface
  • Contain 8 of Earths biomass.
  • Grasslands receive less precipitation than do
    forests and may have long dry seasons.
  • May experience frequent fires
  • Home to large herds of migrating herbivores
  • Three types
  • Steppe
  • Prairie
  • Savanna

70
Steppe
  • Grassland Biome
  • Receives less than 50cm of rain per year
  • Characterized by short bunchgrasses.

71
Steppe
72
Prairie
  • Grassland Biome
  • Characterized by
  • Rolling hills
  • Plains
  • Sod-forming grasses

73
Prairie
74
Savanna
  • Grassland Biome
  • Tropical
  • Ranging from dry scrubland to wet, open woodland

75
Savanna - Africa
76
Review
  • What is a biome?
  • What are the 8 major types of land biomes?
  • What type of land biome covers the largest land
    area?
  • What type of land biome contains the most biomass?
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