Forest diebacks are likely to increase in response to climate change, with increased frequency and intensity of droughts. In line with climate change scenarios, ecoclimatic modelling predicts a decrease in the range of silver fir, a drought-sensitive species, in its southern limit in the French Pyrenees. Diebacks are expected to induce a pulse of resources potentially favorable to certain forest species, e.g. tree-related microhabitats (TreM) for saproxylic species. The impact of forest dieback on biodiversity has nonetheless been poorly studied. As part of the international Climtree project, we set up a balanced sampling design of 56 plots crossing the intensity of local silver fir dieback and the salvage logging of weakened or dead trees. Detailed stand structure metrics and insect communities sampled by Malaise traps (insect MOTUs) or flight-interception traps (saproxylic beetles) have been measured. The structure of fir stands was affected by the level of decline, and to a lesser extent by salvage logging. We indeed observed a slight increase in CWD and in some TreM-bearing trees (crown deadwood, annual polypores , trunk rot holes) with dieback intensity, and a slight decrease in some TreM-bearing trees (crown deadwood, annual polypores) in salvaged compared with unharvested plots. However, these stand changes did not strongly affect local insect assemblages. Guilds of TreM-associated insects did not increase in abundance or richness with dieback-induced increase in resources. In conclusion, forest changes through dieback result in habitat and resource changes with still hard-to-predict impacts at the stand scale on a major reservoir of biodiversity.