What form of succession takes the longest?

Climatic succession, often referred to as primary succession, takes the longest to occur. This process begins in lifeless areas where soil has not yet formed, such as after a volcanic eruption or glacier retreat. It can take thousands of years for ecosystems to develop fully, as pioneer species gradually create conditions conducive to more complex life forms. In contrast, secondary succession, which occurs in previously inhabited areas after disturbances, typically happens much more quickly.