Tree-related microhabitats (TreMs) are specific above-ground morphological singularities borne by standing living or dead trees. They are regularly observed and are crucial issues for forest management in such a way that standards are currently negotiated (e.g. PEFC, FSC, N2000). TreMs depend on tree characteristics. The largest trees play a pivotal role in TreM supply and only the largest trees bear all the TreM types. Living and dead trees are complementary in their supply of TreM types. For instance, cracks and fungus sporocarps are rather borne by snags than by living trees. TreMs distribution patterns are very different in old-growth forests or in managed stands. As «ephemeral resource patches », TreMs host a wide diversity of taxa and play a wide range of pivotal biological roles. Certain Trems, like dendrothelms, host poor but very specific species assemblages. Other TreMs are composite habitats and host several communities. TReMs participate in a complex functional habitat network in species life cycles. How TReMs contribute to local biodiversity depends both on forest type and taxon conservation status. Positive relationships between TReMs density and local species richness are sometimes thresholded. Practical considerations for forest management integrating TreMs include the search for quantitative thresholds. Set-aside areas more than 20 ha in area are needed in mixed forest to conserve TreMs diversity. After a drastic harvesting, the recovery of TreMs needs decades and TreM-associated taxa may have a delayed response. A hierarchical typology is now available as a reference for TreM recording in temperate and Mediterranean European forests. The modelling of TreM ontogenesis is at work, as well as simulation models evaluating long-term effects of management scenarii.