Final answer:
Pioneer species are the initial organisms that colonize barren environments in an ecological succession, altering the habitat to allow other species to establish and leading to greater biodiversity over time.
Step-by-step explanation:
Pioneer species are the first organisms to colonize previously disrupted or damaged ecosystems and begin the process of ecological succession. Typically, these species are hardy and able to grow in harsh, nutrient-poor environments, such as lichens that can grow on bare rock. Pioneer species modify the environment in ways that make it more suitable for other species that follow. They contribute to soil formation by breaking down rock and accumulating organic matter.
As more plants grow and die, the organic matter in the soil increases, improving the soil quality and allowing more complex plant species to colonize. Over time, pioneer species are replaced by more competitive species, leading to a more diverse and stable ecosystem. This process continues until a climax community is established.