Plant Succession on Derelict land
At the pioneer stage, seeds are blown in or brought in by animals and people. Broken concrete, chemical residue and other remains make it hard for plants to put down roots. The land may also suffer from drought, shade and a lack of shelter, all of which make poor growing conditions.
At the building stage, plant roots and the action of the weather break up the ground, creating better rooting conditions. Humus, formed by decaying pioneer plants, improves the soil and creates more fertile growing conditions.
At the climax stage, man made materials are now broken down into a reasonable soil. Taller and more complex plant species, such as trees, can now grow. Plants from earlier stages die out through increased competition for light and water.