What is primary succession?
Primary succession is a type of ecological succession that refers to succession where there is no substrate available. Primary succession can be contrasted with secondary succession, in which substrate is already present.
For example, if a fire completely destroys a forest and all plant life, the soil will still remain. New life can form in the soil and plant life can spread in this area. This would be secondary succession.
If a newly formed volcanic island appears in the ocean, there is no substrate or soil available. The substrate must be formed, and this would be primary succession.