What is the difference between primary and secondary succession?

Here's a breakdown of the key differences between primary succession and secondary succession:

• Starting Point: Primary succession begins in essentially lifeless areas, where soil is not yet formed. This might be on newly formed volcanic rock, sand dunes, or glacial till. Secondary succession, on the other hand, starts in areas where soil is already present, but the existing community has been disturbed or removed.

• Presence of Soil: This is the fundamental difference. Primary succession requires soil formation, while secondary succession occurs on pre-existing soil.

• Pioneer Species: In primary succession, pioneer species, like lichens and mosses, play a crucial role in breaking down rock and accumulating organic matter to begin soil formation. In secondary succession, the soil is already present, so the pioneer species are often fast-growing plants like grasses or weeds that can quickly colonize the disturbed area.

• Speed: Secondary succession generally proceeds much faster than primary succession because the soil and some organic matter are already in place. Soil formation is a slow process.

• Examples: An example of primary succession is the colonization of a newly formed volcanic island. An example of secondary succession is the regrowth of a forest after a fire or logging.

• Nutrient Availability: Nutrient levels are generally very low at the start of primary succession and build up over time as the soil develops. In secondary succession, nutrient levels are usually higher at the outset due to the existing soil.

In essence, secondary succession is a "restart" for a previously established ecosystem, while primary succession is the "creation" of a new ecosystem from scratch.