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Ecological succession is what happens when nature fills in a gap. Whenever a major change occurs in an environment, the species structure, or the makeup of plants and animals in a certain place and the way they interact, changes.
This can happen to an environment after a major event like a wildfire, a severe wind storm, a lava flow, a landslide or after commercial logging. All of these events interrupt the species structure of a particular place and leave room for new or different species to flourish.
The first species to move in to an empty environment will be species that grow or reproduce quickly. These organisms will gradually be replaced by more competitive species, which require a more established ecosystem to thrive. There might be an increase in species diversity for a while, but increased competition can reduce this diversity over time.
Henry Chandler Cowles, an American scientist and professor, first described ecological succession in the late 19th century. Cowles studied the plants growing on the dunes around Lake Michigan, and noticed that the vegetation growing on different dunes was in different stages of ecological development. The older dunes had older plants and more established systems, while the younger ones showed later stages of ecological succession.
There has been plenty of development in this field, as academics have continued to study ecology. H. C. Cowles proposed a fairly regular system of ecological succession, but he didn’t attempt to classify every step in the process. One of the first to follow him, Frederic Clements, proposed an easily predictable system of ecological succession, but another early ecologist, Henry Gleason, pushed back pretty quickly.
Today’s system of studying ecological successions recognizes that many factors play into the process. When an environment is wide open for colonization, plenty of things could move into that space, and plenty of different things could affect the process. Everything from the availability of new species near the open space, to weather patterns as it changes and the conditions will affect the way new species move in and set up a new food chain. Even the interactions of people with the environment and climate change can affect ecological succession.
Primary, Secondary and Cyclic
Primary succession occurs when something like a lava flow creates a brand new, empty environment. Primary succession starts with smaller beings, like microorganisms, moving into a new ecosystem. They’re followed by plants like moss, and then increasingly larger plants. Animals come back once there are enough plants to feed them, and eventually they create a fully functioning ecosystem.
Secondary succession happens when an ecosystem is emptied by a disaster like a wildfire. In this case, the existing structure of the land will affect the way succession moves forward. Everything from the soil composition to remaining seeds or surviving plants and animals will have an effect on the succession. Secondary succession is observed more often than primary succession.
Cyclical succession is a natural process of change. Some species gain or lose prominence in an environment due to any number of factors.