Secondary succession happens on land where a community has been removed or destroyed but the soil remains. Examples include land after a forest fire, a field that has been ploughed and then abandoned, woodland that has been felled, or ground cleared by a flood.Because soil is already present, secondary succession does not begin with lichens or mosses. The pioneers are usually fast-growing plants such as grasses and weeds, which germinate quickly from seeds blown in or already buried in the soil. Roots, underground stems and seeds that survived the disturbance can also regrow.The stages then follow the same pattern as other successions: grasses and small flowering plants are followed by shrubs, and then by trees, until a climax community is reached. Each stage changes the conditions, for example by adding organic matter and by shading the ground, allowing new species to outcompete the earlier ones.Secondary succession is much faster than primary succession because:
• the soil already contains water, mineral ions and organic matter, so there is no need to wait for soil to form;
• seeds, spores and roots are already present in the soil;
• organisms can colonise from undisturbed land nearby.For example, an abandoned arable field in lowland Britain can become scrub within a few decades and woodland within about 100 years, while primary succession on bare rock may take thousands of years.
• the soil already contains water, mineral ions and organic matter, so there is no need to wait for soil to form;
• seeds, spores and roots are already present in the soil;
• organisms can colonise from undisturbed land nearby.For example, an abandoned arable field in lowland Britain can become scrub within a few decades and woodland within about 100 years, while primary succession on bare rock may take thousands of years.