Shared affinity of various forest-dwelling taxa point to the continuity of temperate forests

Effective indicators for biodiversity hotspots and refuges of threatened forest species could help with efforts to mitigate the decline of European forest's biodiversity. 'Ancient forest species' (AFS, i.e. a group of forest vascular plant species that rely on forest continuity) were previously noted as possible indicators of biodiversity hotspots. However, different aspects of the forest continuity may be important for different taxa. Using data from two multi-taxa surveys of central European forests, we examined spatial congruence between the richness of AFS and other forest-dwelling groups in stands that differed in various aspects of forest continuity. We provide evidence for a general positive relationship between the richness of AFS and other forest-dwelling taxa (bryophytes, macrofungi, lichens, beetles, moths and some groups of edaphic organisms) in temperate European forests. The ability of AFS to indicate hotspots of forest biodiversity is not seriously affected by forest management even in the case of long-term intensive and specific management practices such as coppicing. Any easily observable characteristics of the forest environment, excepting the richness of AFS, are unlikely to track exactly the complex effects of forest continuity, habitat quality and the delay in the rise and fall of species diversity of forest communities. Some other perennial plant species associated with beech forests are similar to AFS and regularly occupied the refuges of threatened species. The stands with outstanding biodiversity within the area of deciduous temperate forests can be easily revealed via AFS richness and eventually other similar beech-associated species in the case of beech forests. The retention of all small, mutually isolated refuges of endangered species interspersed within large areas of managed forests may be crucial for the mitigation of biodiversity decline in temperate European forests.