AP BIOLOGY

Detailed explanation-1: -So the correct answer is ‘Shifting’.

Detailed explanation-2: -Secondary succession occurs when the severity of disturbance is insufficient to remove all the existing vegetation and soil from a site. Many different kinds of disturbances, such as fire, flooding, windstorms, and human activities (e.g., logging of forests) can initiate secondary succession.

Detailed explanation-3: -In secondary succession, a previously occupied area is re-colonized following a disturbance that kills much or all of its community. A classic example of secondary succession occurs in oak and hickory forests cleared by wildfire. Wildfires will burn most vegetation and kill animals unable to flee the area.

Detailed explanation-4: -Secondary succession starts when a disturbance (such as wind storms, insect outbreaks, logging, avalanches, bulldozers, or fire) leaves the soil intact. Seeds, spores, and roots usually remain as well. Sites that begin with secondary succession reach the next stage more quickly than during primary succession.