Vegetation changes during 100 years of development of two secondary woodlands on abandoned arable land Original Research Article

Broadbalk and Geescroft Wildernesses were abandoned as arable fields in the 1880s and allowed to develop with little further direct human intervention. Both have now developed into mature mixed deciduous woodland, variants of National Vegetation Classification type W8, Fraxinus excelsior — Acer campestre — Mercurialis perennis woodland. In addition, a portion of Broadbalk Wilderness has been maintained as grassland by removing woody colonists and, latterly, by grazing. The succession from arable to woodland has been recorded at irregular intervals for more than 100 years. Despite its limitations, this is the longest record of the floristic development of secondary woodland on farmland in the UK. Woody species colonised Broadbalk within 10 years, but at Geescroft they were not recorded until 30 years after abandonment. At present, both sites have good overstorey canopies with well developed understories which provide densely shaded conditions. There are currently 17 species of shrubs and trees at each site. The transition from a flora of mainly light-demanding species to shade tolerant species took place within 20–40 years of abandonment. The development of the shade flora within the woods has been characterised by: (1) a high turnover of species; (2) a failure to colonise by some shade-bearing species in the vicinity; and (3) inability of some colonists to spread beyond the wood margins. This appeared to be associated with: (1) dense shade from the closed woodland canopy; (2) competition from established ground flora dominants, particularly Hedera helix; (3) lack of suitable moist soils and open space habitats within the woods; and (4) pronounced acidification of soils in one wood. Some implications for new farm woodland creation are discussed.