Final answer:
Primary succession begins on new land surfaces without soil, such as those left behind by retreating glaciers, and involves soil formation from bare rock due to weathering and biological activity of pioneering species. Secondary succession, in contrast, occurs where soil already exists.
Step-by-step explanation:
One type of primary succession begins after a glacier retreats, leaving rocks and debris behind but not soil. This ecological process occurs on surfaces where no soil exists and virtually no life has previously been present.
Primary succession is characterized by the formation of soil from bare rock due to weathering and the accumulation of organic material from pioneering organisms like lichen. These pioneer species help break down the rock into smaller particles, allowing the gradual build-up of soil. Over time, as soil depth and quality improve, more complex plants can take root, eventually leading to a fully developed ecosystem. In contrast, secondary succession occurs in environments where the soil already exists, such as after a forest fire or the abandonment of agricultural land.
By understanding the differences between primary and secondary succession, we can better appreciate the resilience of nature and the complex processes that lead to the restoration of ecosystems over time.