Differences between Primary and Secondary Succession - Primary vs Secondary Succession

What is Primary Succession?

Primary succession can be described as a kind of eco-succession that occurs in an area that is new and has no suitable soil, and is first colonized with living creatures.
Primary succession is a sequence of events that occur in attempt to create an ecosystem that is stable.
The environments that are created are typically caused by natural processes such as eruptions of glaciers or volcanoes which result in the loss of soil, or the lack of life-forms.

The species of organisms that inhabit these environments are referred to as ‘pioneer organisms which are typically comprised of algae, lichens and fungi.
Primary succession begins with weathering of rocks , forming soil, which is used by the species that was the pioneer.
The initial onset of primary succession is usually or is caused by an element in the body or an external cause.

When a certain amount of soil has established, organisms, such as lichens that have no soil needs, begin to flourish in these regions. The organisms move into the new habitat from a different one.
They also aid in the break-down of mineral-based rock formed by glaciers or lava into the soil, allowing it to be used by other species.
The first species of the genus continue to reproduce, grow in the process of dying, dividing and decaying leaving areas of soil in which other species could grow and thrive.

The decomposition process of these organisms contributes to the organic matter in the soil, thereby contributing to soil development.
The process repeats itself several times over the course of the sequence. At each stage new species emerge from the habitat created by the previous species Some may even take over the species that was previously in place.
In the course of time, fast-growing vegetation covers these areas, covering the majority of the area. The seeds of the largest trees can be sucked into the new ecosystem through the wind or via birds, which then attract other species of animals.

The ecosystem in primary succession is constantly changing with the introduction of new species, which eventually results in the stability of.
The community that forms when the ecosystem is stable the ecosystem is referred to as a “climax community”.
The composition and the ecosystem at this time are more stable than the previous ecosystems.

Primary succession takes a lengthy process that takes many several years to be completed.
Examples of primary succession can be the emergence in a fresh ecosystem in the aftermath of an eruption of a glacier, a volcano or a nuclear explosion.

Examples of primary succession

Primary succession after a nuclear explosion

In the areas that were tested for nukes, it was thought that there would not be any life in these areas for a long time. It was discovered that the primary succession process begins in such regions within the span of 30 years. They are regarded as dead zones since there is no way to live in these areas for a long time. In the course of time, all dangerous radiation resulted from an explosion in nuclear energy is cleared of the region.

As with all other conditions primary succession after nuclear explosions also starts in the process of weathering rocks. When rocks begin to degrade in the process, new species such as algae and lichens are introduced to the environment, leading to the first living groups to emerge. As the succession process is continued, an entirely new set of organisms will replace the previous groups, leading to an increase in organic matter found in these areas. After a period of 100 years or more an established climax community or ecosystem develops within the region.

Primary succession in sand dunes

Seashores are regions that are characterized by extreme conditions due to extreme wind speeds, shifting sand, and a lack of organic matter and nutrients. The surrounding is without stable ecosystems and the first organisms that thrive in the environment are bacteria that live in a symbiotic partnership with the pioneer plants. The roots of these plants permit the plant to be anchored onto the shifting sand, and are modified to avoid loss of water and the absence in organic matter.

The grasses are followed by lichens that use organic matter that is deposited on large stones that are found along the shoreline. As the ecosystem grows the new species emerge and take over the living organisms to ensure a stable group develops. In the end, organisms that are that can survive in high salt concentrations eventually live in the dunes and along seashores.

What is Secondary succession?

Secondary succession can be described as a kind of ecological succession that takes place within an already established ecosystem . The ecosystem can be disrupted due to circumstances like hurricanes or fires and is then rebuilt through other living organisms.
In contrast to the primary succession process, second succession is initiated in an existing environment that has soil.
Secondary succession therefore occurs in a place where the initial succession has been interrupted however, some species of animals and plants may still exist.

This kind of succession typically is triggered by disasters like the storm, forest fire or harvesting, which causes the ecosystem in which it is destroyed.
The beginning of the secondary succession usually occurs due to external causes.
After a forest fire the tall trees die and the first plants that are able to establish in these zones are typically annual.

The next annual plants are low-lying and grasses and some other pioneer species.
The first colonizers of secondary succession are often referred to as “pioneer species,” similar to primary succession.
These species that are pioneers, as opposed to those that are in primary succession generally arise from already-established groups of organisms within the community.

As time passes, changes in the environmental conditions caused by the growth of grasses cause the development of new plant groups like herbs and shrubs.
These are the intermediate species that further create changes in the environment helping to grow higher-growing plants.
Over a lengthy amount of time chemical composition of the surrounding environment is changed back to its pre-fire condition.

There are many elements that influence the direction of succession, such as the dispersal of seeds and the production of seeds.
Other factors such as the shape of the landscape, the pH, climate bulk density, and soil texture also play a role for the overall composition and interaction within the community.
The nature of the community formed after secondary succession depends on the trophic interaction, the initial composition of the environment, and the competition-colonization processes.

The duration required to complete secondary succession is typically shorter than primary succession The secondary succession of an area after a the forest fire can take around 150 years to finish.
Examples of secondary succession could be succession following a the destruction of forests, harvesting or the abandonment of the land or revival following a outbreak of a disease.

Examples of secondary succession

Harvesting, logging, and abandonment of land

The abandonment of crops is a prime illustration of the human-induced secondary succession. Land that is constantly cultivated tends to become depleted of nutrients since the nutrients are systematically taken away due to cultivation. The absence of organic matter results in an unfavourable environment to the growth and development of plants or other species. Following the demise of these areas, the second succession starts when the first the pioneer plant.

The first vegetation produces organic matter and provides nutrients sufficient for the newer species to live in these areas. The vegetation is later replaced by herbs and shrubs which also serve as a barrier to natural disasters, such as erosion of soil. The cropland eventually gets replenished with sufficient nutrients because new communities develop. But, the second succession in landscapes impacted by humans differs from the natural ecosystem due to the soil type as well as the artificial fertilizers used to these areas. This leads to the inundation of the region by plants that are specialized and, in turn, reduces the diversity of the area.

Renewal after diseases

Secondary succession is also common in regions where the current ecosystem is devastated by a disease outbreak. While a disease might be devastating for one species, it ultimately affects the plants that are already present and also other species that are part of the ecosystem. But the seeds or roots of certain plants may remain in the soil, which could trigger an additional succession.

In the same way, the elimination of one species could allow the colonization of another species that may have been competing with the earlier colonizers. Secondary succession creates diversity in an environment because new kinds of organisms could inhabit the same environment.