Trade-off between light availability and soil fertility determine refugial conditions for the relict light-demanding species in lowland forests

- Relict populations are model objects for identifying climate change refugia.
- Plain landscapes tend to encourage shifts of species than formation in situ refugia.
- We analyse habitats of relict, light-demanding plant in lowland forests.
- Required co-occurrence of nitrogen and light availability is limited by close canopy.
- Survival of light-demanding relicts requires cyclic disturbances in tree-stands.

Identifying potential refugial habitats in the face of rapid environmental change is a challenge faced by scientists and nature conservation managers. Relict populations and refugial habitats are the model objects in those studies. Based on the example of Actaea europaea from Central Poland, we analyse the habitat factors influencing relict populations of continental, light-demanding species in lowland forests and examine which habitats of studied species corresponding most closely to ancient vegetation. Our results indicate that the current refugial habitats of Actaea europaea include not only communities which are very similar to ancient open forest but also forests with a closed canopy. Although the populations are influenced by nitrogen and light availability, the co-occurrence of these two factors in forest communities is limited by dense canopy formation by hornbeam and beech trees on fertile soils and in more humid conditions. Our findings indicate that the future survival of relict, light-demanding communities in lowland forests requires low-intensity disturbances to be performed in tree-stands, according to techniques, which imitate traditional forests management.