Succession in Ecology

How does an ecological community develop? Ecological succession describes this process of development, identifying how the community began as well as how and when it stabilizes.

Definition

As you develop and grow there are certain predictable changes that will occur, and they usually happen in a specific order. As a baby, you first learn to roll over, then crawl, then walk. You also learn new skills such as how to feed yourself and how to talk, but each skill you learn builds on those learned before it. Your body also changes as you grow taller, your muscles and bones develop, your hair grows longer, etc.

Ecological succession is the same idea - it is the observed changes in an ecological community over time. These changes are fairly predictable and orderly. Within an ecological community, the species composition will change over time as some species become more prominent while others may fade out of existence. As the community develops over time, vegetation grows taller, and the community becomes more established.

Types

Ecological succession happens for a few different reasons. Primary succession is initiated when a new area that has never previously supported an ecological community is colonized by plants and animals. This could be on newly exposed rock surfaces from landslides or lava flows.

Secondary succession occurs when an area that has previously had an ecological community is so disturbed or changed that the original community was destroyed and a new community moves in. This is more common than primary succession, and is often the result of natural disasters such as fires, floods, and winds, as well as human interference such as logging and clear-cutting.

Seasonal succession is another type of succession, but instead of being the result of a disastrous event, it is caused by cyclical changes in the environment or interactions between the species in a community.

Stages

When succession first begins, pioneer species are the first to colonize the new area. Pioneer species are usually fast-growing, opportunistic, and able to disperse easily. These are called r-selected species. These are things like bacteria, moss, insects, and smaller plants.

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