A comparison of understorey vegetation between untouched and managed deciduous forest in Denmark

The vegetation composition, plant species diversity, and a number of environmental variables of six untouched forest areas were compared with those of seven managed forest areas of similar sizes, geology and topography. The forests ranged in size from 2 to 19 ha and consisted of deciduous, mature trees; all had been continuously forested for more than 200 years. The untouched forests had been without significant management for 35 to more than 130 years. Vegetation composition was measured by frequency analyses in eight sample plots within each study site. The data were analysed by detrended correspondence analysis (DCA), to evaluate the relative influence of the environmental variables on the vegetation composition and degree of heterogeneity, and to look for species characteristic of untouched forests. Paired comparisons between managed and untouched forests were also carried out. The DCA indicated some differences between the two forest types, most probably caused by differences in tree species composition, with the dominance of beech apparently playing a crucial role. Also, soil moisture appeared to influence the vegetation, with more species characteristic of wet conditions present in the untouched forests. Litter depth influenced species distribution but did not differ between untouched and managed forests. No influence of stand structure was apparent, and the comparisons of floral heterogeneity and species diversity showed no differences between managed and untouched forests. Old stands contained fewer species than younger stands. (C) 1997 Elsevier Science B.V.