What is Ecological Succession?
Ecological succession is a basic concept in ecology. I have a long definition written up here on the board of ecological succession, but it’s pretty easy to understand. It’s the generally predictable stages in ecological system undergoes before eventually arriving at a stable climax biotic community best adapted to the prevailing climate, soil, and other conditions in an area.
Basically, ecological succession occurs after something kind of devastating happened in that area. It could be a volcanic eruption, a fire, logging, basically that area has been cleared of vegetation. Ecological succession is the process by which organisms, or plants, come back into that area. Eventually, this area wants to get to a stable climax.
Basically, they want to get to equilibrium. That way, a lot of new plants are having to grow. It’s just kind of business as usual. Some plants are dying. Some new plants are growing. Everything is pretty stable. These plants are going to grow in a certain way depending on the climate, the soil, and other conditions in an area.
The plants are going to grow in a certain way, in a certain area, and in a certain quantity to be suited to the conditions that they are in. First, like I said, the area is cleared of vegetation by fire, logging, volcanic eruptions, or other disturbances. Then, that area is first colonized by what we call pioneer organisms.
This makes sense, because a pioneer is the first person into an area. In this case, it’s the first plant into the area. These are mainly grasses and herbaceous plants. These are organisms that can pop up really quickly. From there, shrubs and small rapidly-growing trees begin to grow. These rapidly-growing trees are ones that require light.
These trees are going to begin to mature and they’re going to get bigger and eventually they’re going to start blocking out the sunlight to the plants below it. What’s going to happen is that as the trees mature, more and more shade-tolerant species appear. The plants that come in after the trees are mature must be shade-tolerant, meaning they’re okay with shade.
From there, those shade-tolerant species are going to appear until the climax community is attained. Once that climax community is attained, then ecological succession has basically come to an end for that area. Many biological communities undergo such rapid man made or other disturbances that they cannot achieve their climax state.
Nevertheless, the concept remains a valid description of old growth or mature ecosystems. Maybe there’s a certain area that is continually being harvested for lumber. It’s going to have trouble coming back fully. Maybe there’s an area totally wiped out by a volcano, then as it starts to grow again another volcanic eruption occurs. Since there are such rapid disturbances in that area, it’s going to be hard for the plants to go back. Under normal circumstances, this is how ecological succession works.