Changes occur all over the world every day. In ecology, changes in the types of organisms that inhabit an area over time is called succession.
In this lesson, we will investigate primary succession.
Definition of Primary Succession
Primary succession is the colonization of new sites by communities of organisms. It often occurs after a devastating event has wiped out the organisms that lived in the area, or with the creation of a new habitat.
Let’s look at a couple examples to see how primary succession occurs.
Primary Succession After a Volcano
Imagine a volcano erupting. Lava flows down the side of the volcano, destroying everything in its path, but when it cools, it forms new land.
Initially, the new land will be barren with nothing living in the area. But after some time, simple organisms will begin to colonize the new land. The organisms that engage in primary succession are known as pioneer species.
Typical pioneer species include simple lichens, algae, and fungi. These simple organisms begin breaking down the resources in the environment and make it suitable for the later introduction of more complex species, such as vascular plants. As these organisms carry out their life processes, they produce waste and some die. This leads to the formation of the organic material that will become soil.
Once a small layer of soil is in place on top of the lava flow, the variety of life will begin to increase much more quickly. The pioneer plants will be crowded out by more complex plants, such as grasses and small shrubs that are able to live in the thin layer of newly formed soil. These small plants will continue to increase the conditions of the newly formed habitat and make way for larger species of shrubs and small- to medium-sized trees.
Primary Succession After an Avalanche
Avalanches are common in mountains that receive large amounts of snowfall. Suppose an avalanche occurs on a mountain and leaves a large ledge of rock exposed that had been previously covered with snow and ice. The first organisms to appear on the rocks would most likely be algae and lichens.
These organisms are known to secrete acidic solutions that can cause small cracks in the surface of the rocks. As water flows into the crack and freezes and thaws with the weather, the rock will be broken into much smaller pieces on the surface. This will be the foundation for a new layer of soil.As cracks in the rocks get larger and more soil is formed through decomposition, it is easier for grass seeds that have been blown in by the wind to take hold and root into the rocky surface.
The presence of these grasses will also make room for small shrubs and trees eventually.
Primary succession is the initial movement of simple organisms, known as pioneer species, into new habitats that have been created. Typically, these new areas of colonization have been made available through major geological events, such as volcanic eruptions and earthquakes.
Primary succession begins with simple organisms that make way for larger and more complex species to inhabit the area.