When an ecosystem starts, it is all just bare rock, with no life. This is how primary succession begins.
Next, lichens grow. Lichens are organisms close to algae or cyanobacteria. They will grow on the rocks. Since they are the first living thing in the area, they are pioneer species, and they must be phototsynthesizers. They will release chemicals onto the rocks that will break down the rocks over the next few years, and turn them into dirt.
Once the soil is there, moss will grow. When it dies, the soil becomes thicker, because organic matter was added. Seeds will be carried to that area by either animals or just the wind. When the soil becomes thicker, weeds and grasses will grow . When the weeds and grasses die, they're added to the soil.
Once again, when the soil is thicker, shrubs and small trees will grow. Pines tend to be the first trees to grow because they need less water and nutrients.
Deciduous trees will grow, but only when the soil becomes even thicker. They replace the pines because they can grow taller, and therefore the pines will die from the lack of sunlight.
It is now a mature, temperate, deciduous forest. It is at the climax community. It is also a mature, stable, and sustainable community, and it is at the end of succession.