Ecological Succession

Sudden Changes• Sudden changes can occur in ecosystems in

a many wayso Forest Fireo Volcanic Eruptions

• Often times, this is very apparent when the vegetation of an area has been wiped out

Ecological Succession• Ecological Succession – Transition in the

species composition of a biological community following ecological disturbance or

• The establishment of a biological community in an area virtually barren of life

Types of Succession• There are two kinds of ecological

succession:o Primaryo Secondary

Primary Succession• Primary Succession – A change in

composition of species over time in an area that never previously supported living things

• The soil or substrates in these places have never had plants growing in it, and soil has not been formed yet

Primary SuccessionTwo common primary succession examples• Succession on Rock or Lava

o Lichens become establishedo Fungus attach lichens to rocks, and hold moisture

that would otherwise flow awayo Lichens flourish and produce acids that speed rock

erosion, accelerating formation of soil o Bacteria, protists, and mosses and fungi appear in

soil, helping put nutrients into the soilo Grasses and weeds begin to growo Eventually trees and shrubs will develop

Primary Succession Example 2• Succession on sand dunes

o Grasses that have evolved to grow in sand grow and help to anchor down the sand (6yrs)

o Shrubs begin to grow after thato Over the next 50-100 years pines and oaks followo Over the next 750-1000 years, beech maple trees

begin to develop

Secondary Succession• Secondary Succession – Begins in habitats

where communities were destroyed by some kind of event but soil remains intact

Secondary Succession ExamplesSuccession on Abandoned Cropland and Farms• Grass and weeds will develop first due to the

high abundance of their seeds• Pines will often take root in the soil next,

followed by oak, hickory, and dogwoods

Climax Community• The last stage in ecological succession is

known as a climax community• Climax Community – A constant balance of

organisms that remains unchanged until another catastrophic event

Sometimes called anold growth forest