Ecological succession refers to the progressive succession of a group of species or community over time. In this regard, there is usually one dominant type of species or community thriving in an ecosystem and where a stable climax community is established. An ecological succession may span decades or millions of years. It may be primary, secondary, or cyclic. A primary ecological succession is an ecological succession that occurs following an opening of uninhabited, barren habitat or that occurs on an environment that is devoid of vegetation and usually lacking topsoil. It is when the area has not been occupied and eventually pioneer species thrive and have stabilized into an ecological community.
An example of primary succession is the initial development of plant or animal communities in an area where no soil initially exists. Specific instances of primary succession are the establishment of pioneer species following a lava flow, a severe landslide, newly exposed glacial tills, etc. The primary succession is important in pioneering the area to create conditions favorable for the growth of other forms of plants and animals.