As you can see, this Volcano erupts and fireballs and lava come out of it. After this Volcano is done spewing fire everywhere, all that will be left is bare rock that is created by the Volcano
Right now, all that's in the environment is bare rock, in a while, lichen will start to slowly break down the rocks into soil.
After many years, the lichen has broken down the rock and soil can now be made so that plants can start to grow here
Now that there is soil here, plants will start to grow and a good environment will be made.
After another few years, grasses have started to grow from the soil. These are the pioneer species, something like a tree wouldn't be known as a pioneer species because they were not the first to grow in this ecosystem, they take much longer to grow than grasses
After even longer, small shrubs start to grow after the grasses. They start popping up around the area with the grasses and soil.
After a few years of waiting, trees have grown into the ecosystem and are now apart of here along with the shrubs and grasses. This doesn't mean that we will have them here for a while, they could be destroyed 100x faster then they were made.