Why does primary succession take place after a landscape has lost all life?

Primary succession occurs in environments that have been rendered essentially lifeless, such as those covered by lava flows, retreating glaciers, or newly formed sand dunes. It is important to clarify that primary succession does not take place simply because a landscape has lost "all life"; rather, it occurs specifically when a catastrophic disturbance has also eliminated the soil or rendered the existing substrate incapable of sustaining life.123

In these barren settings, there is no pre-existing bank of seeds or residual nutrients in the soil to facilitate recovery. Consequently, the area can only return to life through the slow process of primary succession, where pioneer species—such as lichens, mosses, and certain microorganisms—must first colonize the sterile environment. These organisms play a critical role by breaking down rock and adding organic matter, which eventually forms the soil necessary for more complex plant and animal life to establish themselves over time.3451

This differs from secondary succession, which occurs after disturbances that leave the soil and its seed bank intact, allowing for a faster recovery of the biological community.34