Tree-related microhabitats (TreMs) are specific, well delineated above-ground tree morphological singularities occurring on living or standing dead trees. As essential elements for species to develop, feed, shelter or breed during at least part of their life cycle (1), TreMs are key features for many taxa and contribute in the complex network of forest resources for biodiversity. Large and broadleaved trees bear most of the TreMs within a forest stand (2). The spatial pattern of TreMs may therefore be similar to the spatial distribution of these trees. However, this logic is impaired by several processes. Firstly, TreM types are generated by a wide range of natural processes, from stochastic, abiotic events such as lightnings to deterministic, biotic events such as the excavation of a woodpecker breeding cavity. Secondly, forest management strongly impacts the distribution of TreMs. Indeed, management always reduces TreM diversity, alters the relative proportion the TreM types and often shrinks TreM density (3). Logging can also locally produce TreMs such as missing barks along the logging tracks. Furthermore, during tree marking before harvesting operations, forest managers impact on both the distribution of TreM bearing trees and the TreM types they bear. A better knowledge of spatial patterns of TreMs in old-growth forests would help us to promote more biodiversity-friendly forest management practices. We therefore explored spatial patterns of several TreM types in temperate old-growth forests and compared them with patterns in managed stands. In order to better understand the effects of TreM spatial patterns on forest biodiversity, we analyzed the response of TreM-associated saproxylic beetle assemblages to variations in spatial patterns of cavities or polypores. The first results of these studies will be presented in this talk. Finally, we discuss deemed consequences for conservation of TreM-associated taxa in managed forests.