SuccessionEcology Notes

September 8, 2015

Think about it. In 1883, the volcanic island of Krakatau in the Indian Ocean was destroyed by an eruption. The tiny island that remained was completely barren. Within two years, however, grasses were growing. Fourteen years later, there were 49 plant species, along with lizards, birds, and bats. By 1929, a forest containing 300 plant species had grown. Today, the island is blanketed by mature rain forest.

Ecological Succession Definition: a series of more-or-less

predictable events that occur in a community over time. Ecosystems change over time,

especially after disturbances, as new species move in, populations change, and some species die out.

Events During Primary Succession Definition: succession that occurs in an area in which no trace of a

previous community is present.

No soil!

Bare rock exposed.

Occurs after volcanic eruptions or retreating glaciers.

After the event, the first species to colonize barren areas are pioneer species.

Events during Secondary Succession Definition: type of succession that occurs

in an area that was only partially destroyed during disturbance.

Occurs faster than primary succession.

Occurs after wildfires, hurricanes, or other natural disasters.

Processes During Succession Pioneer species may alter the

environment, which changes environmental factors in a way that makes it easier for other species to survive.

As succession continues, species diversity increases.

Think-Pair-ShareLook at the photo below. If you walked from this dune in a straight line away from the beach, what kinds of changes in vegetation would you expect to see? What sort of succession is this?

Climax Communities Succession After Natural Disasters

Events and processes during secondary succession in healthy ecosystems following natural disturbances often reproduce the original climax community.

However, climax communities can look like patchwork quilts. Natural disasters often disturb patches of communities at

different times.

Different patches may be in a different stage of secondary succession.

Succession After Human-Caused Disturbances Ecosystems may or may not recover from extensive human-

caused disturbances.

Example: Clearing and farming in tropical rain forests can change community of microorganisms in the soil. This can prevent regrowth of original community.