The influence of forest management and habitat on insect communities associated with dead wood: a case study in forests of the southern French Alps

1. Dead wood plays a key role in the functioning of forest ecosystems and is appropriate for conservation purposes and for maintaining biodiversity. In this context, in mixed silver fir ancient forests of the southern French Alps, the respective influence of management status and decay stages were assessed together with assemblages of saproxylic invertebrates. 2. Although the structure of the saproxylic insect composition showed a strong dependence on the different stages of decaying wood, with groups of species restricted to one particular stage, the other part of this structure was only slightly influenced by the management status. 3. In early successional stages of dead wood that generate ephemeral habitats suitable for specialists, the assemblage of species could locally become extinct very quickly. In intermediate stages which were colonised by other assemblages of species, the richness and abundance of some groups were probably positively correlated with historical continuity at a local scale. 4. In the case of suitable long persistent habitats colonised by species with limited dispersal ability, some old established populations could be temporarily deprived of their potential habitats. However, the actual populations of invertebrates have gone through spatio-temporal discontinuities in a metapopulational context at the landscape level.