Ecological succession is the gradual process through which ecosystems change and develop over a given time frame. This process occurs in no particular direction and aims at establishing a stable community. The resultant final community is, therefore called the climax community.
Seral stages are the individual stages of succession, they are not discrete but a continuum of individual events. A disturbance usually precedes succession.
Causes of succession.
There are three major causes of succession as follows:
- Initiating causes– inclusive of biotic (activities of other living things) and climatic (wind, fire, erosion etc.) factors which destroy the population of a region.
- Continuing causes– also referred to as ecesis, these are non-stop processes such as competition and migration. They cause changes in soil nutrients and soil pH.
- Stabilizing causes– they include climatic factors that stabilize the community.
Types of succession
There are two types of succession in ecology, namely primary and secondary succession.
Primary succession.
A series of changes in the community that occurs on an entirely new habitat that has never been colonized. For instance, a dune or an area where lava has flown.
Secondary succession.
A series of community changes occurring on a previously colonized, but damaged habitat.
Succession happens on various timescales that can range from a day to thousands of years. For example, it takes years for a climax woodland to develop while the succession of fungi in cow dung may occur in a short period as three months.
Examples of ecological succession.
- Growth of hardwood trees (oak and poplar) in the red pine planting area. Subsequent morality of the sun to love red pines and increased shading are the consequences of this hardwood tree growth. The growth of sun-loving pine seedlings is prohibited by the shaded forest floor conditions caused by the pines. Therefore, there is a decline in growth of pine forest as a consequence of hardwood growth.
- The succession “garden plot”.
This garden plot was established in April 2000. The initial plants grown in this plot were made up of species with the ability to tolerate periodic mowing as a means to control this grass ecosystem. As time passed, with the removal of constant mowing stress, other plant species came into existence. The undisturbed soil-litter interface increased its water retention abilities allowing a wider variety of plants to grow. Woody and taller plants established themselves shading out the sun-loving grass. It is expected that there will be an establishment of a new forest.
Does ecological succession ever stop?
The climax community concept in ecological succession represents a stable end product of the sequences of succession. For instance, in the landscape region and climate of Nature Trail, the climax community is the Oak-Poplar Forest, which maintains itself for a very long time. Up to this point, ecological succession is said to have stopped.
However, due to external activities such as volcanic eruptions and fires, the Oak-Poplar Forest may reset the succession process. With the constant existence of such forces, it is not accurate to definitively say ecological succession ever stops.
