Succession. Ecological Succession Is studied by ecologist. An ecologist is a scientist that studies the interactions among organisms and their environment.

SuccessionSuccession

Ecological SuccessionEcological Succession

Is studied by Is studied by ecologist.ecologist.

An ecologist is a An ecologist is a scientist that scientist that studies the studies the interactions among interactions among organisms and organisms and their environment.their environment.

EcologicalEcological Succession Succession

Is a series of more Is a series of more or less predictable or less predictable changes that occur changes that occur in a community in a community over time.over time.

Occurs because Occurs because every organism every organism changes the changes the environment it environment it lives in.lives in.

There are two There are two typestypes– PrimaryPrimary– SecondarySecondary

Primary SuccessionPrimary Succession

Begins in an area Begins in an area with no remnants with no remnants of an older of an older community.community.

Pioneer species Pioneer species change these change these barren areas.barren areas.– An example is a An example is a

lichen (a fungus lichen (a fungus and alga)and alga)

Primary SuccessionPrimary Succession

A lichen converts A lichen converts atmospheric atmospheric nitrogen into nitrogen into useful forms that useful forms that other organisms other organisms can utilize to can utilize to break down rock break down rock and dead organic and dead organic material to from material to from soil.soil.

Lichen

Primary Succession: Sand Dune to ForestPrimary Succession: Sand Dune to Forest

Dune grassess cottonwoods and shrubs evergreens oaks beeches maples

Secondary SuccessionSecondary Succession

Occurs after a disturbance (wildfire Occurs after a disturbance (wildfire or hurricane) effects a community or hurricane) effects a community without destroying it completely.without destroying it completely.

Proceeds faster than primary Proceeds faster than primary succession because the soil succession because the soil survives a disturbance.survives a disturbance.

Secondary SuccessionSecondary SuccessionIn the image below, a former In the image below, a former bogbog in in MaineMaine has almost completely filled has almost completely filled

Secondary SuccessionSecondary Succession

Soil already present.Soil already present.

Primary vs. SecondaryPrimary vs. Secondary

No soilNo soil Pioneer speciesPioneer species Weathering & Weathering &

decompositiondecomposition Humus and sand Humus and sand

increase over timeincrease over time End = climax End = climax

communitycommunity

Soil already existsSoil already exists Seeds have Seeds have

suitable soil suitable soil conditions.conditions.

Occurs much fasterOccurs much faster Climax community.Climax community.

Climax CommunitiesClimax Communities

Is the final stage of ecological Is the final stage of ecological succession in which a relatively succession in which a relatively constant environment and species constant environment and species composition is reached.composition is reached.

Can be seen as a community that Can be seen as a community that has developed in response to the has developed in response to the prevailing climatic conditions prevailing climatic conditions

Climax CommunitiesClimax Communities

Are not always uniform and stable because Are not always uniform and stable because they do not always follow the same path.they do not always follow the same path.

May be destabilized by human-caused May be destabilized by human-caused disturbances.disturbances.

Figure 53.20 Spruce and hemlock forestFigure 53.20 Spruce and hemlock forest