Patterns of regeneration and ground vegetation associated with canopy gaps in a managed beechwood in southern England

In autumn 2001, 15 canopy gaps were selected for study in Rumerhedge Wood, a semi-natural, mesotrophic beechwood in southern England. The gaps were located in mature, beech-dominated stands, and had originated from openings created during a thinning in the early 1980s and wind damage in 1987/1990 and/or the consequent salvage operations. The extent of each gap and surrounding trees were mapped. Tree/shrub regeneration, ground vegetation, bare earth, leaf litter and canopy openness (using a canopy-scope) were measured within and around the gaps using a 5 5-m grid and placing a 1 1-m quadrat at each grid intersection (total number of quadrats = 400). Most of the gaps were <75 m 2 in area. The largest was 241 m 2 . They were generally irregular in shape and there was little or no understorey present. Most surrounding trees were beech Fagus sylvatica L. Bramble Rubus fruticosus L. formed a moderate to dense ground vegetation below most gaps and declined around the edges only once the gap opening was substantially obscured. Apart from a few larger saplings, most regeneration was small and of beech. Most of the latter appeared to be in their fi fth or sixth growing season, were 10 -35 cm tall, had an erect base and fl at top, had increased by <5 cm in height during 2001 and were not browsed by deer. Their height and growth form was related to (1) their position within gaps, (2) the degree of canopy openness and (3) the cover of ground vegetation. This was translated into the following zonation -(1) around the centre of larger gaps: canopy openness increased to >15 per cent; bramble cover was near complete; litter depth was low; many places had no beech seedlings, but some of the few present were among the tallest, most upright and fastest growing; (2) towards the edges of the large gaps or directly below smaller gaps: canopy openness was about 4 -10 per cent; bramble cover was slightly less; beech seedlings were moderately abundant but patchy, generally shorter, more fl at topped and slow growing than in the gap centre, albeit some were still among the tallest, most upright and fastest