Afforestation or natural succession? Looking for the best way to manage abandoned cut-over peatlands for biodiversity conservation

We investigated the plant species diversity in patches with natural non-forest vegetation (NN), with forest communities that had developed where there was a spontaneous succession of vegetation (called: natural forests, NF), and with planted forests (PF) within cut-over peatlands located in central Poland. We studied (1) how diverse is plant composition in actively managed and in abandoned cut-over peatland areas, (2) how does afforestation influence wetland species composition, and (3) does natural plant succession in abandoned cut-over peatlands favour peatland regeneration and the maintenance of typical peatland species. We also defined the ecosystem services (with special attention to supporting services) and we analysed the conflicts and synergies of two cut-over peatland utilization options (abandonment and conventional forestry).An ANOVA test was used to analyse statistical differences in the diversity index, phytosociological units and Ellenberg index. Ecological conditions of NN, NF and PF were described on the base of Ellenberg indicator values (EIVs). A modified permutation test using mean randomized EIVs was used to check the significant differences in Ellenberg values.The results show that the vegetation of NN, NF and PF areas differ significantly in mean number of species, Shannon diversity and evenness index. The analyses of Ellenberg values indicated that the light and moisture conditions of NN, NF and PF differ markedly. The development of forest cover, both natural and anthropogenically created, leads to an increase in plants species diversity. However, the encroachment of numerous shade-tolerant forest species does not compensate for the reduction in characteristic peatland species. The afforestation of degraded peatland areas may be an option for management, but in every single case the decision for afforestation ought to be preceded by the recognition of the initial state of the species richness of degraded and potentially managed wetland. The most valuable wetlands with preserved peatlands flora should be actively restored for biodiversity conservation.

► Plant species richness of afforested abandoned cut-over peatlands increases.
► Afforestation has negative consequences for peatland flora.
► Non-forested peatland remnants with preserved unique flora should be restored.
► Contemporary peatland utilization options are determined by provisioning and supporting ecosystem services.
► Afforestation of totally degraded peatlands may be an option of their management.