Succession

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Habitat restoration requires a vibrant ecological succession to replace the natural plants and animals that once lived in a region. Ecological succession, or natural succession, consists of two components: primary succession and secondary succession. In primary succession, life establishes itself on an area that has little or no living things. Examples of primary succession are plants that grow on rock exposed by a receding glacier or on a cooled lava bed in the shadow of a volcano. Secondary succession comprises a series of related but different living communities replacing each other in sequence. For example, many valleys are actually prehistoric lakebeds that filled with eroded soils over thousands of years and interfered with the lake’s aquatic plants. As the plants died, organic debris settled and decomposed and the lake became shallower, then the lake’s water evaporated and minerals formed a hard, flat surface. Finally, new bushes and weeds scratched out a living on the bleak, open plain. At some point in this progression, reptiles find this habitat to their liking, predators move in, and as new plants grow, additional species find food and habitat. As a result, a lush valley has replaced an ancient aquatic ecosystem.

Human-made structures also go through succession. These processes may take a hundred years or more but, in the end, a fortunate few places return to the conditions of an earlier time. The following hypothetical


Ecological succession in plant life creates new ecosystems that develop over decades to centuries. As these ecosystems evolve from simple mosses to multispecies forests, animal populations also change and biodiversity develops. By returning land to nature, biodiversity eventually returns minus the species that have already gone extinct.

example describes situations in which plant and animal diversity changes and species adapt to the existing environment from one phase to the next.

1. a woodland and meadow are cleared for settlers’ homesteads
2. generations of descendants plant crops on the land
3. small farms sell to a large agricultural producer that plants thousands of acres
4. the agricultural company goes bankrupt and landowners buy small pieces to plant
5. the landowners plant orchards
6. the landowners convert the orchards to vineyards
7. the vineyards are abandoned and left unattended
8. plants and trees overgrow the vines
9. a woodland reestablishes on the original land

Actions such as clear-cutting forests, plowing meadows, establishing ranch lands, or planting grasslands with agricultural crops disrupt natural succession. Some activities cause succession to go backward to a previous phase. For instance, a controlled fire that clears part of a forest exposes bare rock and leaves only small ground-covering plants. This means the ecological
succession must begin again from that point to rebuild the forest.

Urban activities that repeatedly disrupt ecological successions force the animals living there to find new habitat continually. In time this stress may weaken a species’ population to the point of extinction.