How does soil quality change during succession?

During succession, soil quality generally improves, becoming more fertile and better at retaining water and nutrients.

In the early stages of succession, the soil is often poor in quality, lacking in nutrients and organic matter. This is because the area is usually newly exposed or disturbed, such as after a volcanic eruption or a landslide, and has not yet had time to develop a rich soil profile. The first organisms to colonise these areas, known as pioneer species, are typically hardy plants like lichens and mosses that can survive in these harsh conditions. These pioneers start the process of soil formation by breaking down the bare rock into smaller particles through weathering.

As these pioneer species die and decompose, they add organic matter to the soil, which starts to build up a layer of humus. This increases the soil's ability to retain water and nutrients, making it more hospitable for other plant species. These new arrivals, in turn, contribute their own organic matter when they die and decompose, further enriching the soil.

Over time, the soil becomes deeper and richer in nutrients, supporting a greater diversity of plant species. This increased plant cover also helps to protect the soil from erosion and further improves its water-holding capacity. The soil's structure also changes, becoming more granular and crumbly, which improves its aeration and makes it easier for plant roots to penetrate.

In the later stages of succession, the soil reaches a state of equilibrium, where the rate of nutrient input through decomposition is balanced by the rate of nutrient output through plant uptake and leaching. This mature soil, also known as climax soil, is typically fertile and well-structured, supporting a diverse and stable community of plants and animals.

In conclusion, the quality of soil changes significantly during succession, starting as a harsh, nutrient-poor substrate and gradually transforming into a fertile, well-structured medium that can support a diverse range of organisms. This process is driven by the activities of the organisms themselves, particularly plants, which contribute organic matter to the soil and help to shape its physical structure.