In an area with barren sand, you would find grasses like Lyme grass, while in the mountains you would find pioneer plants like lichens. The type of pioneer plants you find in an area depends on what type of environment it is.
Any species of pioneer plant is going to be a hardy one that can survive in poor quality soils. These types of plants often have adaptations like long roots, root nodes full of bacteria and leaves that use transpiration. This starts a cycle that will enrich the soil, making a soil that will support the secondary plants that will take over as time passes. The cycle consists of the pioneer plants dying and creating plant litter. They then break down as leaf mold, or some might call it leaf compost, which enriches the soil.