Community Properties

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Community Properties

• AP Environmental Science
• Chapter 4

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What is a Property?

• It is something that helps define a substance or
  thing.
• In this case we are defining the community. So
  what can we look at to give us a better
  understanding of this community thing?

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Properties of a Community

• Productivity
• Diversity
• Complexity
• Resilience
• Stability
• Structure

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Changes in a Community

• Communities change over time.
• The agents of this change are complex and
  include
• Ecological succession
• Exotic species introduction
• Human intervention/management

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Objective 1

• Discuss productivity, diversity, complexity, and
  structure of biological communities and how these
  characteristics might be connected to resilience
  and stability.

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Primary Productivity

• The rate of biomass production
• Solar radiation conversion to chemical energy
• Basically.
• How much energy is available for life to grow???
• Lets take a look-see.

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Where does life live?

• Check out the map again.
• Is the life living where
• the most energy
• is available?
• Is it what you
• would expect?

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How about the Productivity of the Ocean?
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What limits Primary Productivity?

• Amount of sunlight available
• Water available
• Nutrients available
• Just A NOTE
• Less than 1 f the energy from the sun is used
  for photosynthesis. The rest has bigger fish to
  fry.

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So why do we care about Primary Productivity?

• Primary Productivity
• Allows life to exist.
• Its how energy gets into the food chain and food
  web.

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Abundance and Diversity
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Abundance

• The total number of organisms in the community.
• Simple count
• them all!

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Diversity

• The measure of the number of
• different species,
• ecological niches,
• or genetic variation
• present in an ecosystem.

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Different Species

• VS.

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Ecological Niches
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Genetic Variation

• VS.

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In general

• As productivity goes up
• Diversity goes up
• Abundance goes up
• What do you think happens when Productivity goes
  down?

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Complexity and Connectedness

• Complexity
• The number of species at each trophic level
• The number of trophic levels in the community

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EXAMPLES

• DIVERSITY DOESNT MEAN NECESSARILY COMPLEXITY.
• A DIVERSE COMMUNITY IS NOT COMPLEX IF IT HAS A
  SIMPLE FOOD CHAIN.

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Simple System
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Complex system
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A really complex web
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Resilience and Stability

• There are three types of stability or resiliency
  in an ecosystem
• Constancy (lack of flux)
• Inertia (resistance to change)
• Renewal (ability to repair after
• disturbance)

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The connections

• Complexity lends itself to stability.

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The connections

• Complexity can withstand disturbance
• UNLESSthe keystone species are disturbed.

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Edges and Boundaries

• Edges Boundaries between habitats or ecotones.

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Edges and Boundaries

• Closed communities
• Sharply divided community
• Open communities
• Gradual or indistinct boundaries

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Objective 2

• Explain how ecological succession results in
  ecosystem development and allows one species to
  replace another.

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What is succession??

• Its a natural gradual change in the landscape.
• What is the landscape?
• The plant and animal life that lives in a
  terrestrial or aquatic ecosystem.

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Succession Happens!

• Humans dont like change.
• Too bad it happens.
• It happens both on the land (terrestrial) and in
  the water (aquatic).

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Terms of Succession

• Lets discuss the basics before we get into the
  difference between terrestrial and aquatic
  succession.
• Terms to know
• Primary Succession
• Secondary Succession
• Pioneer Species
• Ecological development
• Climax community
• Equilibrium community
• Fire-climax community

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And Life begins..

• Life began theoretically in an aquatic setting.
  The land was unoccupied.
• Picture something like this

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SO what happened?

• Weathering happened.
• Wind and rain
• Wore away at the
• Stone. This
• created
• Cracks and
• smaller
• Rock pieces. In the
• Meantime..

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Eventually..Primary Succession begins.

• PIONEER
• SPECIES
• Such as moss
• (that has no
• roots And can live very basically)
• came to grow
• here.
• This is called Primary Succession.

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Ecological Development

• As debris and organic material collect they form
  soil.
• This is an environmental modification caused my
  organisms
• Or ecological development.
• It also allows for..

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Decomposition and Weathering continues..

• Eventually there
• Is enough
• Dead moss
• That has been
• Broken down
• To create soil.
• Once a little
• Soil is established,
• Herbs take off!
• This is Secondary
• Succession!

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After the herbs .
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Come the shrubs.
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And then the young trees.
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Which eventually turns to a climax forest!
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Some communities never reach a climaxthey like
disruption.

• These are called Equilibrium or disclimax
  communities.
• Examples
• Grasslands
• California Chaparral
• Some Coniferous forests

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Equilibrium or disclimax communities Grasslands

• Fire is needed
• To keep the
• grasslands alive.
• Why?

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Equilibrium or disclimax communities California
Chapparel
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Equilibrium or disclimax communities Coniferous
forests
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Fire-climax communities

• Plants in these communities are adapted to resist
  fires and quickly reseed and recover from fires.
• Many require fire to eliminate competition or to
  reproduce.

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Objective 3

• Give some examples of exotic species introduced
  into biological communities and describe the
  effects such introductions have had on indigenous
  species.

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Invasives Here in WI

• Invasive Plants of Wisconsin
• Garlic mustard
• Common Buckthorn
• Invasive Animals of Wisconsin
• Gypsy Moth
• Zebra Mussel

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Why Are Invasives A Problem?

• They compete with native plants and animals
• Often because they are out of their habitat they
  have no predators, hence they reproduce out of
  control causing an imbalance

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Questions?