Natural colonisation of abandoned land by secondary succession has been observed at several sites and preliminary results published in Using natural colonisation to create or expand new woodlands (PDF-63K) - Forestry Commission Information Note 23.
The experimental site at Aldewood was established in 1995 on poor grassland with a clay soil that was prone to waterlogging.
By 1999 the vegetation on site was a community of mixed herbs and grasses with occasional shrubs.
Two years after abandonment 5 tree species had invaded the site. A majority of the seedlings were ash, the largest of which were about 50 cm tall in 1999.
The site at Sudbury was established in the corner of an arable field after a crop of wheat had been harvested.
The vegetation that developed on site was influenced by the herbicides applied to control weeds. This picture shows the boundary between an untreated plot where grass dominates, and a plot treated with graminicide which has a more mixed flora.
Five species of tree colonised within two years but 80% of the seedlings present were ash or field maple. Seedlings grew poorly and four years abandonment the largest seedlings were only 30 cm tall.