How does an ecosystem transition from primary succession to secondary succession

Primary succession is when there isn't any soil when a new community begins.

Secondary succession is when an event such as a fire destroys an area but leaves the soil.

Primary succession would transition to secondary succession by starting off without any soil. Overtime the community would begin to grow and then soil would appear and plants would start to grow. It would then change to Secondary succession whn an event destroys that area leaving just the soil behind.

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.