Primary succession
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Primary succession is one of two types of ecological succession of plant life, and occurs in an environment in which new substrate, devoid of vegetation and usually lacking soil, is deposited (for example a lava flow). (The other type of succession, secondary succession, occurs on substrate that previously supported vegetation before a disturbance destroyed the plant life.) In primary succession pioneer plants like mosses and lichen plus algae and fungus plus other abiotic factors like wind and water start to "normalize" the habitat, creating conditions nearer the optimum for vascular plant growth; pedogenesis or the formation of soil is the most important process. These pioneer plants are then dominated and often replaced by plants better adapted to less austere conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based. A good example of primary succession takes place after a volcano has erupted. The barren land is first colonised by pioneer plants which pave the way for later, less hardy plants, such as hardwood trees, by facilitating pedogenesis, especially through biotic acceleration of weathering and the addition of organic debris to the surface regolith.
Primary succession occurs following an opening of a pristine habitat, for example, as previously stated a lava flow, an area left from retreated glacier, or abandoned strip mine. In contrast, secondary succession is a response to a disturbance, for example, forest fire, tsunami, flood, or a abandoned field.
