Primary Succession
Primary succession takes place on newly exposed or newly formed land. The land is initially colonised by pioneer species. The stages involved are:
1) Pioneer species
- Pioneer species are the first species to colonise the newly exposed land.
- Pioneer species are specialised to live in the harsh conditions of the exposed land.
- E.g. There is no soil so water and nutrient levels are poor.
- E.g. Marram grass is a pioneer species that can survive in the sand because it has very long roots.
2) Soil formation
- Pioneer species help to break down substances on the exposed land to form soil.
- When pioneer species die, they are also decomposed which contributes to soil formation.
3) Colonisation by new species
- The formation of the soil makes the environment less hostile.
- New species colonise the less hostile land.
- When the new species die, the organic matter within the species is released into the soil by decomposition.
4) Altering abiotic conditions
- When species die, the composition of the soil is changed. Soil is an abiotic (non-living) factor.
- When new species colonise the area, they are also altering the abiotic conditions.
- E.g. If taller species or species with larger leaves grow, the light exposure in the environment is changed.
- New species may also alter the environment so that the pioneer species can no longer survive.
- E.g. Sand sedge colonises coastal ecosystems and makes the environment less suitable for marram grass.
Example
- An example of primary succession is following the eruption of volcanoes in Hawaii.
- As lava flows into the ocean, new land is continually being formed.
- Pioneer species colonise the solidified lava.
