Potential contribution of the seed bank in coniferous plantations to the restoration of native deciduous forest vegetation

In this study, we compared the soil seed bank and current vegetation under coniferous plantations and adjacent native deciduous forests. The objective was to assess how much of the initial plant diversity is retained in such plantations, and the potential to restore this initial plant community from seed bank in case of reversion to broadleave stands. Four stands growing s ide by side and with different dominant species were selected at two locati ons (site of Haye: Quercus petraea, Pseudotsuga menziesii, Pinus sylvestris and Picea abies; site of La Petite-Pierre: Quercus petraea, Fagus sylvatic a, Pinus sylvestris and Picea abies). In each stand, ground vegetation was surveyed and soil seed bank was sampled. Composition of ground flora and se ed bank of stands were quite different: only 11 to 30% of the species were in both the ground flora and the seed bank. Composition of the seed bank wa s mainly influenced by site location and sylvicultural practices such as th e type of afforestation or the tree cover. Species richness of seed banks a nd vegetation were higher in the site of Haye than in the site of La Petite -Pierre. Seedling density strongly decreased with stand age. Whereas betwee n 65 and 86 % of species found in the ground vegetation of native deciduous stand were also present in the understory or the seed bank of mature conif erous stands, this was only about 50 % in young coniferous stands. Species of deciduous stands which were absent from coniferous stands were typical o f old forests. In contrast, species mainly found in the coniferous stands w ere often ruderal. In the studied areas, it would be possible to restore up to 86 % of the native deciduous forest vegetation, but some plant species typical of ancient forests may have disappeared during the coniferous stage . (C) 2001 Editions scientifiques et medicales Elsevier SAS.