After an extreme disturbance, like a wildfire, volcanic eruption, or flood, the first organisms to move into the area are called pioneer species. These are typically:

* Lichens and mosses: They can survive in harsh conditions with little to no soil, and they break down rock to create a thin layer of soil.

* Bacteria and fungi: They decompose dead organic matter, further enriching the soil.

* Annual plants: These plants have a short life cycle and can quickly produce seeds, allowing them to take advantage of the newly available resources.

* Insects: They feed on decaying matter and help to spread seeds.

These pioneer species are opportunistic and hardy, able to withstand the extreme conditions of the disturbed area. They play a vital role in primary succession, the process of ecological change in an area that was previously devoid of life.

As the pioneer species establish themselves, they gradually change the environment, making it more suitable for other species. Over time, the area will undergo a series of changes, ultimately leading to a more complex and stable ecosystem.