Factors influencing the rate of formation of tree‐related microhabitats and implications for biodiversity conservation and forest management

Abstract

1. The retention of trees bearing tree-related microhabitats (TreMs) has become an important means of conserving biodiversity in production forests. However, we lack estimates of TreM formation rates and evidence on factors driving TreM formation. 2. Based on the observation of 80,099 living trees from 19 species groups in Europe and Iran, we estimated the probability of TreM occurrence on trees and the associated rate of first TreM formation as a function of tree DBH, management, tree species group and random site effects. We built a separate model for each of 11 TreM groups. 3. The hazard rate of first TreM formation (defined as the probability of formation of a first TreM forming on a tree that is known to have none, during an infinitesimal DBH increment) increased with DBH for some TreM groups like breedingwoodpecker-hole, rot-hole or root-concavity, indicating an acceleration in TreM formation during tree growth. However, it decreased with DBH for TreM groups like bark-loss or dendrotelm, indicating slower formation on very large trees. Most TreM groups had reduced formation rates in managed forests (last logging less than 100 years ago) compared to unmanaged forests (no logging for at least 100 years), with the exception of dendrotelms. No general difference appeared | 493

Combined retention of large living and dead trees can improve provision of tree-related microhabitats in Central European montane forests

“…Thus, time may not have been sufficient to develop new TreMs specific to deadwood. Previous studies predicted the formation rate of TreMs on living trees (Courbaud et al 2017(Courbaud et al , 2021, which increased with DBH for most of the TreM categories. However, reliable time series based on longitudinal observations are still needed to understand TreM development (formation and persistence) on both living and dead trees.…”

Broadleaf Retention Benefits to Bird Diversity in Mid-Rotation Conifer Production Stands

“…This process takes time and thereby favours hollow formation in larger older trees (Courbaud et al, 2022). Although we did not survey retained trees for the occurrence of cavities, it is reasonable to assume a higher prevalence of these structures in retained trees than in the production trees due to their older age and larger size (Larrieu et al, 2014;Courbaud et al, 2022). The average DBH of the retained trees in our study was 34 cm, and close to 10% of all retained trees were larger than 50 cm.…”

“…Hence, a tree is suitable for the establishment or improvement of a nest cavity when the wood is softened by fungal infection (in particular for smaller birds). This process takes time and thereby favours hollow formation in larger older trees (Courbaud et al, 2022). Although we did not survey retained trees for the occurrence of cavities, it is reasonable to assume a higher prevalence of these structures in retained trees than in the production trees due to their older age and larger size (Larrieu et al, 2014;Courbaud et al, 2022).…”

Evaluation of Azure Kinect Derived Point Clouds to Determine the Presence of Microhabitats on Single Trees Based on the Swiss Standard Parameters

“…Measuring forest biodiversity is often done via the use of biodiversity indicators, such as volume of dead wood (Christensen et al, 2005) or more recently, via the measurement of TreMs (Bütler et al, 2020). TreMs inventories can provide an estimate of species richness in forests as they represent the presence of certain ecosystems on the tree trunk (Courbaud et al, 2022).…”