Who is using tree-related microhabitats (TreMs)?

Laurent Larrieu vient de publier un nouvel article sur les dendromicrohabitats (TreMs) dans la revue Biological Conservation en collaboration avec des collègues allemands de l'European Forest Institute (EFI). Il s’agit d’une revue de littérature pour comprendre comment la littérature scientifique existante sur les TreMs est répartie entre les différents taxa et les différentes échelles spatiales. Les principales hypothèses étaient que (i) la plupart des études se concentrent seulement sur quelques formes de TreM et quelques taxa, oubliant des pans entiers de la biodiversité associée à ces structures et (b) que les différentes échelles spatiales (i.e. l’arbre-habitat, la placette/peuplement, le paysage) ne sont pas représentées de manière égale. Le principal résultat est que les études se sont concentrées sur quelques TreMs, à l’échelle de l’arbre-habitat, et sur seulement quelques groupes taxonomiques qui ne sont pas représentatifs de l'ensemble de la biodiversité. En conclusion, les auteurs :

• à inclure une plus grande diversité de TreMs et à prendre en compte une diversité de groupes taxonomiques dans les recherches, en particulier ceux qui sont traditionnellement négligés (e.g. les épiphytes, les excroissances et les exsudats pour les TreMs, la meiofaune pour les taxa)

• à réaliser de futures études pour évaluer l'association de plusieurs groupes taxonomiques avec différents TreMs à plusieurs échelles.

Dutta T., Larrieu L., Schuck A. (2025). Who is using tree-related microhabitats (TreMs)? Biological Conservation, 307, https://doi.org/10.1016/j.biocon.2025.111180

Abstract:

Tree-related microhabitats (TreMs) are well-delineated tree structures that provide important resources and refuge to thousands of species. For these reasons, TreMs have been recommended as an indirect indicator of biodiversity in European forests. We conducted a literature review to understand the scale at which different taxonomic groups are associated with TreMs in Europe. Across a pool of 54 papers, we found that TreMs were most frequently studied at the scales of sampling plots (n = 28, 58 %) and individual trees (n = 18, 33 %), and less frequently at the stand scale (n = 5, 9 %). Two studies addressed the landscape scale in addition to the plot and stand scale (n = 1). Birds, saproxylic beetles and bats were the most frequently studied taxonomic groups overall and at the plot scale, whereas amphibians were only studied at the scale of individual trees. Tree cavities were the most frequently studied TreM-form at all scales and were often associated with bats and saproxylic beetles. Crown deadwood and fungal fruiting bodies were associated with saproxylic beetles, and tree injuries were frequently associated with bats. Sample sizes across all TreMs-taxa combinations were low, allowing only descriptive analyses and interpretation. The largest sample size for saproxylic beetles investigated at the plot scale (n = 15) across different TreMs, were found to be significantly associated more than 20 % of the times with tree cavities (33 %), tree injuries (21 %) and fungal fruiting bodies (20 %). We recommend future studies to evaluate species-TreM associations for the poorly studied TreMs such as epiphytic and epixylic structures, excrescences, and exudates, or poorly studied taxa such as meiofauna, and to evaluate multiple scales and taxonomic groups when possible. Our review could also serve as a starting point to consider which taxonomic groups would benefit from those management practices that enhance TreM-associated biodiversity.