Hello! I'm your succession instructor! In the first stage of this primary succession after volcanic eruptions occurred, the only thing that is left from the disaster is bare rock. No biotic-factors are alive currently.
After a period of time, lichen grows of exposed rocks or cracks between the bare rock.
After some more time, small annual plants and more lichens start to bloom.
After more years past, shrubs and more flowers start to grow.
More and more centuries past, the bare rock is now filled with trees, flowers and plenty of shrubs