Ecological Succession

Ecological succession is the observed process of change in the species structure of an ecological community over time.

Birth Growth Maturity Stability Death

Those species that can grow the most efficiently and produce the most viable

offspring will become the most abundant organisms in an ecosystem

Changes that takes place during succession can depend on four things:

1.Abiotic factors- moisture, temperature, and wind

2.Biotic factors – invasive species (ex. Weeds)

3.Human Actions4.Natural Disasters

Primary succession: invasion of life onto abiotic

environmentexamples:lichens and mosses on rocks start making soilairborne seeds germinate in sand or ash Secondary succession: changes after biotic

community is established or after a disturbanceexample:fire -- meadow – old field – thicket – seral forest –

climax forest

Weed species are considered as an invasive species. What makes them successful? They are:

Better competitors (they outcompete grasses and other plant for nutrients)

Greater growth rates (grow fast, grab nutrients)

Greater dispersal ability (seeds move great distances from parent plants for nutrients)

Better colonizers of disturbed ground Greater reproductive potential (mature

quickly and produce many seeds) Greater tolerance to environmental

extremes Lower rates of disease

Succession can occur in a typical garden very quickly if weeds are allowed to take root.

1. It begins when weed seeds blow into a garden, take root, grow, and develop and out-compete the existing natural garden species.

2. The weeds will absorb all the water and nutrients, grow tall and tower over the natural garden species, robbing them of sunlight

3. The last step of ecological succession occurs when the native species die out, and the weeds will become the dominant species of the garden.

Succession occurs after an environment gets destroyed, as a volcanic eruption.

Ex. Lichens and mosses spring up in rocks in which water collects, eventually weathering the lava rock to form soil. Lichens are called “pioneer organisms” because they help establish the soil for seeds to take root, to continue to the next stage of succession

Succession occurs because of : facilitation: growth of one species

increases the growth of another examples:lichens/mosses create soil: benefits other

plantslegumes fix nitrogen, fertilizing soil: benefits

other plants competition: growth of one species

hinders the growth of another example: tall-growing trees shading out