AP BIOLOGY

Detailed explanation-1: -Primary Succession occurs when land becomes barren due to a major geological event or when a significant natural disaster wipes out all of the ecosystem’s organisms. Once the area has been rid of its organisms, the ecosystem must start over from the Pioneer Community.

Detailed explanation-2: -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.

Detailed explanation-3: -Primary succession happens when a new patch of land is created or exposed for the first time. This can happen, for example, when lava cools and creates new rocks, or when a glacier retreats and exposes rocks without any soil. During primary succession, organisms must start from scratch.

Detailed explanation-4: -Primary succession occurs in essentially lifeless areas-regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier.

Detailed explanation-5: -Harvesting, Logging and Abandonment of Crop Land The abandonment of land previously utilized for crops is a common cause of human-induced secondary succession. Land which has been intensively cultivated is often nutrient poor, with the nutrients having been repeatedly removed through harvest or logging.