Answer: to create the soil
Explanation:
An ecological succession can be define as a series of changes that occur in the biotic community with respect to the changes that occur in the abiotic or non living factors such as soil, temperature, water, natural calamity and others in a particular time duration until the ecosystem attains stability.
A primary succession is an initial stage of succession which occurs in a land which was not previously occupied by any living species and the physical environment is not favorable to support the life initially. A pioneer species is the one which makes the environment suitable for the survival of other species. For example Lichens, they secrete acids over the rocks which causes their disintegration into particles of soil. The accumulation of soil facilitates the growth of the plants.
