© 1988 by Institute of Chartered Foresters
Changes in the Ground Flora under Plantations on Ancient Woodland Sites
Nature Conservancy Council, Northminster House Peterborough, PEI IUA
At six areas in southern Britain, the ground flora under plantations showing a range of ages and tree species was examined and compared with that in nearby remnants of semi-natural mixed oak woodland. The ground flora in each stand was assessed by listing the vascular plant species and total ground flora cover in randomly placed 200 m2 quadrats. There were 2-20 quadrats per stand and 308 quadrats in all.
Differences between sites were the major factors influencing the groupings produced by a TWINSPAN classification of the quadrat data. The forestry treatments appeared to alter the distribution and abundance of particular ground flora species within broad limits set by the previous woodland vegetation on each site. Grass-dominated quadrats, typical of recently felled areas on base-rich soils, and very species-poor quadrats under dense conifer and beech plantations were separated out from the main block of data.
Species richness and abundance increase immediately after clear-felling, decline during the thicket stage and subsequently increase as the stands are thinned.
Semi-natural mixed oak stands, pine plantations and some conifer-broadleaf mixtures had higher values for ground flora species-richness and cover than beech, Norway spruce and Lawson cypress stands of similar age. In plantations consisting of alternating even-aged strips of oak and Norway spruce, more species survived under the oak strips.
The replanting of ancient semi-natural woodland has other implications for nature conservation independent of effects on ground flora species, for example effects on the shrub layer or invertebrate populations.