We explain what ecological succession is, its relationship with evolution and examples. In addition, primary and secondary succession.
What is ecological succession?
Ecological succession or natural succession it is the natural evolutionary process by which some species gradually take the place of others less adapted to the environment. This process occurs without human intervention and occurs within the framework of the dynamics of competition between species in the same ecosystem.
Nevertheless, succession and evolution are not exactly the same. Evolutionary succession, that is, the replacement of one species by another better adapted to the dynamics of the environment, occurs over a long period of thousands of years, which is how long it takes for a new species to appear.
On the other hand, the replacement in an ecosystem of one species by another competitor, can take place in a few hundred years. In any case, the tendency in both cases is to increase the level of complexity of life, that is, to replace generalist species with specialist species, adapted to increasingly specific conditions.
Ecological succession is a natural process of organizing life in the same habitat, which tends to drive life towards change and adaptation, which is why it is part of the dynamics of ecosystems. This process can be understood in two stages: primary and secondary.
Primary succession
It is called a primary sequence that occurs when a new habitat is in formation, being colonized by the first forms of life capable of doing so. For example, newly exposed live rock or newly formed wastelands can be colonized by plant forms such as mosses or small plants, known as pioneer species.
These species benefit from the decomposition of the rock by erosion and meteorism, serving as the first link for future species that will take advantage of the new habitat, replacing the pioneers as more and more layers of life are added, forming a new ecosystem.
Secondary succession
Secondary succession is distinguished from primary in that it is the result of violent changes in the conditions of an existing ecosystemi.e. from major disruptions such as fires, floods, massive illnesses, etc.
In these cases, the succession is restarted, but no longer from zero as in virgin biotopes, but rather giving rise to more specialized species, that is, to species adapted to changes in the environment, which take the place of those eradicated by the violent event. happened.
Examples of ecological succession
Ecological succession can easily be seen in major geological events, such as the volcanic eruption. On the one hand, the ejected magma and boiling materials soon cool, adding new virgin layers of substrate to the Earth, as occurs in the volcanic islands of the Pacific, which gradually expand in size.
Once the new ground has cooled, primary succession takes place, and over time a new ecosystem will emerge where there was nothing initially.
But at the same time, volcanoes are razing existing ecosystems, burning forests and burying burrows under lava. This pushes the species into a struggle to adapt to the devastated territory, allowing certain species to proliferate first and occupy the place that previously belonged to others, as occurs with pyrophilic plant species (which feed on burned land).