The process of primary autotrophic succession is completed through the following steps

The process of primary autotrophic succession is completed through the following steps:

1. Nullation :

This refers to the development of bare area without any form of life. The causes of nucleation are of the following three types:

(i) Topographic:

The existing community may disappear due to soil erosion by gravity, water or mud.

(ii) Climate:

Dry period, hails and storms, fire, frost etc. may also destroy the community, (ill) Biotic: The most important biotic factor such as man is responsible for the destruction of forests, grasslands for industry, agriculture and housing etc.

2. Invasion :

This is the successful establishment of a species in a bare area. The species reaches the new site from any other sea. The process is completed in three successive stages.

(i) Migration:

The seeds, spores of the species reach by water, air etc. This process is called as migration.

(ii) Establishment (Ecesis):

After reaching the new area, the process of establishment of the species as a result of adjustment takes place. This is known as Ecesis.