• Bioenergy;
  • deadwood;
  • Pinus pinaster ;
  • Quercus spp

Abstract.  1. The expanding interest in harvesting stumps for bioenergy may represent a potential threat to forest biodiversity. Whereas stumps are common in managed stands, knowledge of their associated saproxylic assemblages is still incomplete.

2. We used emergence traps to sample saproxylic beetle assemblages in oak and pine large-diameter (>20 cm) logs and stumps and compared the assemblages from the two sources.

3. With 64–84.5% of the species pool in oak and pine, respectively, stumps definitely constituted a suitable substratum for many saproxylic species in managed forests. Higher species density suggested that stumps are more diverse habitats than logs. Stumps also host rare species and natural enemies of bark beetles. For both tree species, the assemblage composition was significantly different between logs and stumps. The dissimilarity between substratum types was predominantly due to turnover, especially for oak.

4. Our results revealed that not only do stumps constitute a substitute for some log-dwelling species; they also provide a suitable breeding substratum for many species that may be at risk in case of massive exportation of stumps for bioenergy purposes.