Plant Succession

Many plant communities are not self-sustaining. A field in the temperate deciduous forest biome will remain a field only as long as it is grazed by animals or mowed regularly. If these factors are eliminated, the balance tips in favor of other species. The newcomers will, in turn, establish conditions that no longer favor them but promote the growth of still other species. The revered naturalist and writer, Henry David Thoreau, called this process succession.

Primary Plant Succession

The process of plant succession begins just as soon as a land area capable of supporting plant life is formed. Some examples:

Bare rock succession in a temperate deciduous forest biome

Bog succession

Another example of plant succession occurs as shallow ponds gradually fill in with soil washed in from the surrounding terrain and organic matter produced by underwater plants.

As we walk from the edge of a poorly-drained, boggy pond back into a temperate deciduous forest, we pass through a series of zones that recreate in space the plant succession that has been occurring in time.

one passes concentric zones, each representing a later stage of plant succession as the soil has become firmer and the shade denser.

Secondary Plant Succession

Lumbering, farming, fires, and hurricanes interrupt the process of succession by removing the dominant plants in the community. Their elimination sets the stage for a new succession to begin.

The many abandoned farms in New England (I live on one) illustrate this. People often wonder why our pioneers built stone walls through the woods. The answer is that they did not. The walls in the woods today once marked the boundaries of fields and pastures, but when cultivation and grazing ceased, a secondary succession began. Where I live,

In general, plant succession is a reflection of the increasing efficiency of the community at intercepting the energy of the sun and converting it into chemical energy. As one stage of succession follows another,

The graph (from Whittaker, R. H., Communities and Ecosystems, Macmillan, 1970) shows the changes in number of species, biomass, and net productivity during secondary succession in a temperate deciduous forest over a period of 160 years.

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8 November 2015