Who is using tree-related microhabitats (TreMs)?

Tree-related microhabitats (TreMs) are specific structures on living or standing dead trees (such as cavities, dead branches, injuries, fungal fruiting bodies) that provide key resources — like shelter, nesting sites, and food — for a wide range of species. These microhabitats are increasingly recognised as structural indicators of biodiversity because they represent conditions supporting many forest organisms.

In this review, the authors conducted a literature synthesis of 54 studies to understand which taxonomic groups utilise TreMs in European forests and at which spatial scales these associations have been studied. They found that most research has focused on birds, saproxylic beetles, and bats, particularly at plot and individual tree scales, while many groups (e.g., amphibians, epiphytic organisms) and certain TreM types remain understudied.

Cavities were the most frequently analysed TreM form and were often associated with bats and saproxylic beetles. Other TreM types (e.g., fungal fruiting bodies, injuries) showed positive associations with beetles and bats. Overall, the review highlights data gaps in taxa and scales and suggests prioritising research on poorly studied TreMs and taxa, as well as assessment at stand-to-landscape scales to better support biodiversity-oriented forest management.