Primary Succession Definition and Examples

Primary succession is the type of ecological succession in which organisms colonize an essentially lifeless area. It occurs in regions where the substrate lacks soil. Examples include areas where lava recently flowed, a glacier retreated, or a sand dune formed. The other type of succession is secondary succession, in which a previously occupied area is recolonized after most of the life has been killed. The end result of succession is a stable climax community.

Steps of Primary Succession

Primary succession begins in areas essentially devoid of life. It follows a predictable series of steps:

1. Barren Land: Primary succession occurs in an environment that has never supported complex life. Bare rock, lava, or sand don't contain nutrient-rich soil or nitrogen-fixing bacteria, so plants and animals cannot initially survive. Primary succession occurs on land, but it can also occur in the ocean where lava has flowed.
2. Pioneer Species: The first organisms to colonize the rock are called pioneer species. Terrestrial pioneer species include lichens, moss, algae, and fungi. An example of an aquatic pioneer species is coral. Eventually, pioneer species and abiotic factors, such as wind and water, break the rock and increase the nutrient levels enough that other species can survive. Pioneer species tend to be organisms that disperse spores over great distances.
3. Annual Herbaceous Plants: As pioneer species die, organic material accumulates and annual herbaceous plants start to move in and overtake the pioneer species. Annual herbaceous plants include ferns, grasses, and herbs. Insects and other small animals start to colonize the ecosystem at this point.
4. Perennial Herbaceous Plants: Plants and animals complete their life cycles and improve the soil to the point where it can support larger vascular plants, such as perennials.
5. Shrubs: Shrubs arrive when the ground can support their root system. Animals can use shrubs for food and shelter. Shrub and perennial seeds are often brought into the ecosystem by animals, such as birds.
6. Shade-Intolerant Trees: The first trees have no shelter from the sun. They tend to be short and tolerant of wind and extreme temperatures.
7. Shade-Tolerant Trees: Finally, trees and other plants that tolerate or prefer shade move into the ecosystem. These large trees overtop some of the shade-intolerant trees and replace them. By this stage, a wide variety of plant and animal life may be supported.

Ultimately, a climax community is attained. The climax community usually supports more species diversity than earlier stages of primary succession.

Primary Succession Examples

Primary succession has been well-studied following volcanic eruptions and glacier retreat. An example is the island of Surtsey, off the coast of Iceland. An undersea eruption in 1963 formed the island. By 2008, about 30 plant species had been established. New species are moving in at the rate of two to five species per year. Forestation of volcanic land may require from 300 to 2,000 years, depending on the distance to seed sources, wind and water, and chemical composition of the rock. Another example is the colonization of Signy Island, which has been exposed by glacier retreat in Antarctica. Here, the pioneer communities (lichens) established within a few decades. Immature communities established within 300 to 400 years. Climax communities have only become established where environmental factors (snow, stony quality) could support them.

Primary vs. Secondary Succession

While primary succession describes the development of an ecosystem in a barren habitat, secondary succession is the recovery of an ecosystem after most of its species have been eliminated. Examples of conditions leading to secondary succession include forest fires, tsunamis, floods, logging, and agriculture. Secondary succession proceeds more rapidly than primary succession because soil and nutrients often remain and there is usually less distance from the site of the event to soil seed banks and animal life.

Sources

• Chapin, F. Stuart; Pamela A. Matson; Harold A. Mooney (2002). Principles of Terrestrial Ecosystem Ecology. New York: Springer. pp. 281–304. ISBN 0-387-95443-0.
• Favero-Longo, Sergio E.; Worland, M. Roger; Convey, Peter; Lewis Smith, Ronald I. (July 2012). "Primary succession of lichen and bryophyte communities following glacial recession on Signy Island, South Orkney Islands, Maritime Antarctic". Antarctic Science. Vol. 24, Issue 4: 323-336. doi:10.1017/S0954102012000120
• Fujiyoshi, Masaaki; Kagawa, Atsushi; Nakatsubo, Takayuki; Masuzawa, Takehiro. (2006). 'Effects of arbuscular mycorrhizal fungi and soil developmental stages on herbaceous plants growing in the early stage of primary succession on Mount Fuji". Ecological Research 21: 278-284. doi:10.1007/s11284-005-0117-y
• Korablev, A.P.; Neshataeva, V.Y. (2016). "Primary Plant Successions of Forest Belt Vegetation on the Tolbachinskii Dol Volcanic Plateau (Kamchatka)". Izv Akad Nauk Ser Biol. 2016 Jul;(4):366-376. PMID: 30251789.
• Walker, Lawrence R.; del Moral, Roger. "Primary Succession". Encyclopedia of Life Sciences. doi:10.1002/9780470015902.a0003181.pub2