Lava flows from a volcanic eruption leaves the area with no layer of soil.
Nothing but rocks are the survivor of the disturbance which then lead to plants starting to grow again.
The lichens and moss then live on these exposed solid rocks, slowly breaking down the rock into smaller pieces that eventually lead to a thin layer of soil. These are called Pioneer species
As the Pioneer species finish breaking down the rocks into small amounts of organic matter, it soon turns into a very thin layer of soil.
In the layer of soil, small adaptable plants such as grasses and weeds begin to form. Then, those plants that die will put more organic matter back to the soil and create other plant species. Many animals will may soon adapt to this area.
With thick soil that deliver more weird and complex plants, shrubs are small, fast growing trees that survive and begin to develop. More animals begin to move back into the area.