Compare and contrast primary succession and secondary succession in one paragraph

Ecological succession are mainly of two types: Primary succession and secondary succession.Both the succession leads to establishment of a stable community on a barren land . Primary succession begins from a primitive substratum where no community existed before. Here the first organisms are called pioneers. Secondary succession takes place in an area where a community exited before but disappeared due to some cause.

Explanation:

Ecological succession is a natural process by which some locality becomes successively colonized by different group or communities.
Succession can be caused by initial causes like climatic as well as biotic factor and continuing causes like migration , aggression competition etc.
Based on the nudity of the land succession can be primary or secondary.
Secondary succession can again be autogenic or allogenic.