Restoration of an abandoned species-rich fen-meadow in Denmark: changes in species richness and dynamics of plant groups during 12 years

A period without management had transformed the vegetation of a species-rich fenmeadow, with no external change in the hydrological regime, into three communities: alder thicket (unmanaged 15 years), tall herb and sedge dominated communities (unmanaged 11 years). Following reintroduction of management (felling of alder thicket, mowing and grazing) the vegetation development was monitored and species cover was measured along a permanent transect before and during 12 years of restoration succession. Management increased the density of fenmeadow species and made the three communities more similar. The appearance of new fen species and the increase in species density followed immediately after the introduction of management. Thereafter, only a few new species appeared and the turnover index stabilised. Management by mowing and grazing both increased species density of herbs and promoted establishment of biennials and hemicryptophytes. Other plant groups responded differently to management: mowing increased total cover, the cover of grasses, and promoted phanerophytes and chamaephytes; grazing reduced the influence of these groups and promoted 'sedge & rush' and geophytes. Restoration was particularly successful in the felled alder thicket, but the success was caused by spreading of species from the pool of species within the site and establishment of species having persistent seed bank, i.e. inherent good potential for restoration. The results are discussed in relation to use of functional plant groups and Ellenberg N- and L-indices as response indicators for monitoring restoration progress.