Final answer:
During primary succession, pioneer species like lichens and certain plants colonize new land, break down the substrate, and contribute to soil formation, which then allows for more diverse plant communities to establish, leading to mature ecosystems.
Step-by-step explanation:
The types of species present during primary succession are often hardy pioneer species that can colonize new or bare land, such as after a volcanic eruption. These species, which include certain lichens and plants, are adapted to thrive in harsh conditions with little to no soil. They work to break down the substrate and accumulate organic material, thereby contributing to the formation of soil that can support other species.
Over time, as population density and quality of soil improve due to the activities of the pioneer species, more diverse plant communities such as mosses and grasses establish. These, in turn, improve conditions further, allowing shrubs and eventually forest trees to grow, leading to an increase in population size of various species and culminating in a mature ecosystem.