In 1974-76 164 permanent 10 × 10m plots were recorded at alternate intersections of a 100 × 100m grid in Wytham Woods, Oxfordshire. Tree and shrub data were collected from all the plots in 1974-76, from 27 in 1984-85 and from all but one in 1991-92. Changes in the structure and composition of the wood are assessed in terms of canopy cover, mean tree diameter, basal area and species occurrence. The wood has become more open (reduced canopy cover) partly through management, partly natural processes such as windthrow and disease. The shrub cover has also declined greatly, probably because of increased deer browsing. Most stands are predominantly young growth and for the wood as a whole mean tree diameter, basal area and tree height have increased. The overall composition of the wood has changed little, but there has been a significant decline in mean wood species number per plot from 5.8 to 4.1, mainly through declines in understorey species and young oak. Elm cover has been reduced by disease and birch also suffered preferentially from windthrow.
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