Factors influencing the diversity of deadwood, a crucial microhabitat for many rare and endangered saproxylic organisms

Deadwood (DW) is a crucial component of habitats, with both its volume and diversity considered critical for saproxylic organisms. Deadwood position, thickness, snag height, species composition, and decay stage were studied in the context of eight factors characterizing habitats, stands, and management types. A multivariate multiple regression model was used to analyze data from 29,098 sample plots.Deadwood diversity (a 5-dimensional dependent variable) was found to strongly depend on DW volume in a given area and on the species composition of the stand. A less pronounced effect was exerted by site fertility and moisture, the age and DBH structure of the stand, and terrain type. The model also revealed that the location of the stand in managed or unmanaged areas did not have a direct impact on deadwood diversity, with stand features being more important.Analysis of individual qualitative characteristics showed that DW thickness was affected by the same seven factors as DW diversity. DW position and decay stage were influenced by four factors: site fertility and moisture as well as stand age and species composition. In addition to the species composition of stands, DW species composition was positively influenced by more fertile and moist sites and a more varied DBH structure of stands. A significant negative effect was identified for high DW volume, which indicates that the deadwood accumulated in a stand tends to be derived from the tree species that was most vulnerable to mortality at a given time. Snag height variation was influenced by such stand characteristics as age, DBH structure, and species composition; the other significant factors were DW volume and terrain type. The diversity levels of individual DW characteristics were significantly and positively correlated, which means that all of them often revealed high or low diversity at the same time.Our study showed that forests with low DW volume additionally face the problem of DW quality. Thus, efforts to increase DW volume should be focused on those DW characteristics that are lacking (large trees, species di-versity, and height variation of snags). DW diversity is lower in younger stands, with little DBH variation, and in forests which are more easily accessible, located mostly in the lowlands, and growing on less fertile and dry or mesic sites.

Automated summary

Deadwood is a crucial component of habitats for saproxylic organisms, with its volume and diversity playing vital roles. A multivariate multiple regression model was used to analyze the factors influencing multiple characteristics of deadwood. The study found that deadwood diversity strongly depends on deadwood volume and species composition. Other factors, such as site fertility and moisture, stand age and DBH structure, and terrain type, have a less pronounced effect. Analysis of individual qualitative characteristics revealed common factors influencing deadwood thickness, position, and decay stage. The study also found a positive correlation between the diversity levels of individual deadwood characteristics.