We explain what ecological succession is, its relationship with evolution and examples. Also, primary and secondary succession.
What is ecological succession?
Ecological succession or natural succession is the natural evolutionary process by which some species gradually take the place of others less well adapted to the environment. This process occurs without human interventions and occurs within the framework of competition dynamics between species in the same ecosystem .
However, succession and evolution are not exactly the same thing . Evolutionary succession, that is, the replacement of a species by another better adapted to the dynamics of the environment, occurs over a long period of time, thousands of years, which is how long it takes for a new species to appear.
On the other hand, the substitution in an ecosystem of a species by another competitor , can occur 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 organization of 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.
It can help you: Habitat and ecological niche
primary succession
Primary succession is the one that occurs when a new habitat is being formed , being colonized by the first life forms capable of doing so. For example, newly exposed living rock or newly formed wastelands may 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
After a fire, the first plants to gain ground become successors.
Secondary succession differs from primary succession in that it is the result of violent changes in the conditions of an existing ecosystem , that is, of important interruptions such as fires, floods, massive diseases, etc.
In these cases, the succession is restarted, but not from scratch as in virgin biotopes, but giving rise to more specialized species, that is, species adapted to changes in the environment, which take the place of those eradicated by the violent event. happened.
Examples of ecological succession
On volcanic islands, the species succeed one another on the new substratum.
Ecological succession can be easily seen in major geological events, such as volcanic eruptions . On the one hand, the expelled magma and boiling materials soon cool, adding new virgin layers of substratum to the Earth , as occurs in the volcanic islands of the Pacific, which gradually expand their size.
Once the new terrain has cooled, primary succession takes place, and over time a new ecosystem will emerge where there was initially nothing.
But at the same time, volcanoes devastate existing ecosystems, burn down forests , and bury burrows under lava. This pushes 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).