Ecological Succession:

Be able to describe the process of primary and

secondary succession in a named habitat.

Ecological Succession:

Be able to describe the process of primary and

secondary succession in a named habitat.

Environmental SystemsEnvironmental Systems

Primary succession: The gradual establishment, through stages, of a climax ecosystem, that has not been occupied before.

Primary succession: The gradual establishment, through stages, of a climax ecosystem, that has not been occupied before.

Primary succession will occur after a volcanic eruption

Primary succession will occur after a volcanic eruption

Primary succession occurs after a glacier retreats

Primary succession occurs after a glacier retreats

Glacier Bay, AlaskaGlacier Bay, Alaska

Secondary succession: The reestablishment, through stages, of a climax ecosystem, that has been cleared by natural or human means.

Secondary succession: The reestablishment, through stages, of a climax ecosystem, that has been cleared by natural or human means.

Secondary Succession: A bare patch of ground covered in

grasses two years later

Secondary Succession: A bare patch of ground covered in

grasses two years later

Secondary SuccessionSecondary Succession

When natural vegetation has been disturbed, removed or destroyed.

Abandoned farms

Burned forests

Heavy pollution

Deforestation

A huge storm

When natural vegetation has been disturbed, removed or destroyed.

Abandoned farms

Burned forests

Heavy pollution

Deforestation

A huge storm

Some Definitions:Some Definitions: Sere: Another name for succession. A set of stages

of evolution of an ecosystem.

Pioneer stage: First stage in a sere which is dominated by opportunist species. (r-strategists)

Climax community: Populations of organisms living together in the climax stage. (K-strategists)

Climax stage: Final stage in a sere where all species are in balance. For example: A mature forest

Sere: Another name for succession. A set of stages of evolution of an ecosystem.

Pioneer stage: First stage in a sere which is dominated by opportunist species. (r-strategists)

Climax community: Populations of organisms living together in the climax stage. (K-strategists)

Climax stage: Final stage in a sere where all species are in balance. For example: A mature forest

Pioneer SpeciesPioneer Species

Pioneer species tend to be r-strategists Pioneer species tend to be r-strategists

Small adultsize Short lifespanRapidreproduction

HabitattemporaryHabitat patchyLongdistancedispersalMany smallseeds

High densityindependent mortality

Climax Species tend to be K-strategists

Climax Species tend to be K-strategists

K - strategistsK - strategists

Large adultsize Large lifespan SuccessfulseedingestablishmentrareLarge adultsize

Habitat uniformDispersallocalFew largeseedsHigh densitydependent mortality

Sequoia (redwood) trees are K-strategistsSequoia (redwood) trees are K-strategists

Lithosere: Succession on landLithosere: Succession on land The evolution of bare ground to forest. The evolution of bare ground to forest.

Pioneer species……………………………………Climax forest

Hydrosere: Succession of

ponds and lakes to forests.

Hydrosere: Succession of

ponds and lakes to forests.

Describe the changes that you see.

Describe the changes that you see.

Hydrosere:Hydrosere: The gradual conversion of ponds and lakes to forest

ecosystems.

With time ponds and lakes are gradually filled with eroded sediments.

The sediments moves in the shorelines and eventually fills in the lake.

The plant sequence is as follows: lake plants, reeds, grasses, shrubs, & trees.

The gradual conversion of ponds and lakes to forest ecosystems.

With time ponds and lakes are gradually filled with eroded sediments.

The sediments moves in the shorelines and eventually fills in the lake.

The plant sequence is as follows: lake plants, reeds, grasses, shrubs, & trees.

Succession along a beach:Succession along a beach: The gradual conversion of sandy beaches and desert margins to

forest.

Wind moves sand into dunes

Organic material, seeds, and moisture are blown in behind the dune.

Hardy salt tolerant grasses and vines establish themselves trapping more soil.

Plant succession follows the lithosere.

The gradual conversion of sandy beaches and desert margins to forest.

Wind moves sand into dunes

Organic material, seeds, and moisture are blown in behind the dune.

Hardy salt tolerant grasses and vines establish themselves trapping more soil.

Plant succession follows the lithosere.

Succession along a beach:Succession along a beach:

Be able to describe and explain the changes during succession.Be able to describe and explain the changes during succession.

Changes during successionChanges during succession

Pioneer species: lichens and mosses that extract nutrients from dust and bare rock.

Then: Bacteria, fungi, insects, small worms add organics to the soil

Early succession plants: grasses, herbs Midsuccessional plants: grass and low scrubs Late successional plants: trees Climax community: depends largely on climate

and edaphic factors

Pioneer species: lichens and mosses that extract nutrients from dust and bare rock.

Then: Bacteria, fungi, insects, small worms add organics to the soil

Early succession plants: grasses, herbs Midsuccessional plants: grass and low scrubs Late successional plants: trees Climax community: depends largely on climate

and edaphic factors

Climatic factorsClimatic factors

Precipitation

Temperature

Insolation (Incoming Solar Radiation)

Precipitation

Temperature

Insolation (Incoming Solar Radiation)

Edaphic FactorsEdaphic Factors

Factors having limiting affects on plant growth that are not climatic. Soil Factors

Examples:

Alkalinity of soil

Extreme acidity

Iron toxicity

Zinc deficiency

Low nutrients in soil

Factors having limiting affects on plant growth that are not climatic. Soil Factors

Examples:

Alkalinity of soil

Extreme acidity

Iron toxicity

Zinc deficiency

Low nutrients in soil

Rate of Primary SuccessionRate of Primary Succession

Primary succession is fastest in humid tropics.

It is slowest in the dry polar areas.

Why?

Primary succession is fastest in humid tropics.

It is slowest in the dry polar areas.

Why?

Succession after a forest fire

Succession after a forest fire

Secondary Succession after a fireSecondary Succession after a fire

Nutrient release to soil Regrowth by remnant roots and seeds Invasions from neighboring

ecosystems Rapid restoration of energy flow and

nutrient cycling

Nutrient release to soil Regrowth by remnant roots and seeds Invasions from neighboring

ecosystems Rapid restoration of energy flow and

nutrient cycling

Secondary succession after farming

Secondary succession after farming

Changes during successionChanges during succession

Biomass increases Resource allocation; nutrients initially

stored in soils become stored in vegetation.

Mineral cycling slows

Biomass increases Resource allocation; nutrients initially

stored in soils become stored in vegetation.

Mineral cycling slows

Changes in Energy FlowChanges in Energy Flow Trophic levels increase from 2 levels to 4 -5

levels. More trophic levels transfer more energy. Food webs become more complex. The total productivity of an ecosystem

increases. Biomass and biodiversity is maximized in a

climax ecosystem.

Trophic levels increase from 2 levels to 4 -5 levels.

More trophic levels transfer more energy. Food webs become more complex. The total productivity of an ecosystem

increases. Biomass and biodiversity is maximized in a

climax ecosystem.

Changes in ProductivityChanges in Productivity

Abiotic ChangesAbiotic

Changes

pH: 8 5.5N: increasesC: increasesExchangeable ions decrease

Know the factors affecting the nature of climax communities.Know the factors affecting the nature of climax communities.

The Nature of climax communities.

The Nature of climax communities.

The system is in a stable equilibrium

Remember the system is open Matter and energy may cross system boundary. Inputs are in proportion to outputs.

The system changes less thus keeping habitats intact over time.

The system is in a stable equilibrium

Remember the system is open Matter and energy may cross system boundary. Inputs are in proportion to outputs.

The system changes less thus keeping habitats intact over time.

The Climax Community:The Climax Community: Specialization is encouraged as all niches are occupied.

Each species must enhance competitive abilities and take care of young.

High nutrients available (but used) due to large amounts of biomass.

High moisture available as forests capture their own transpiration and encourage rain.

Specialization is encouraged as all niches are occupied.

Each species must enhance competitive abilities and take care of young.

High nutrients available (but used) due to large amounts of biomass.

High moisture available as forests capture their own transpiration and encourage rain.

Climax Community:Climax Community:

Mineralized nutrients (Nitrogen) increases. Organic matter in the soil increases Mineral cycling decreases as plants are adapted

to maintaining themselves and not growing or establishing themselves.

These nutrients become less available to plants as they adhere to soil particles or are stored as dead matter in ground.

Mineralized nutrients (Nitrogen) increases. Organic matter in the soil increases Mineral cycling decreases as plants are adapted

to maintaining themselves and not growing or establishing themselves.

These nutrients become less available to plants as they adhere to soil particles or are stored as dead matter in ground.

Compare early to late successionCompare early to late succession Biomass Productivity Food chains Species diversity Niche specialization Feeding relationships Size of individuals Life cycles Population control mechanisms Fluctuation Mineral cycles Stability

Biomass Productivity Food chains Species diversity Niche specialization Feeding relationships Size of individuals Life cycles Population control mechanisms Fluctuation Mineral cycles Stability

Early succession Late succession

Biomass small HighProductivity high LowFood chains Short Long, complexSpecies diversity Low HighNiche specialization Broad NarrowFeeding relationships General SpecializedSize of individuals Smaller Larger?Life cycles Short LongPopulation control density density

independent dependentFluctuation More Less pronouncedMineral cycles Open Tend to be closedStability Low High

Early succession Late succession

Biomass small HighProductivity high LowFood chains Short Long, complexSpecies diversity Low HighNiche specialization Broad NarrowFeeding relationships General SpecializedSize of individuals Smaller Larger?Life cycles Short LongPopulation control density density

independent dependentFluctuation More Less pronouncedMineral cycles Open Tend to be closedStability Low High

Source of this PowerPoint:www.nido.cl/~doehlke/successio

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Source of this PowerPoint:www.nido.cl/~doehlke/successio

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