Disentangling effects of structural deadwood characteristics on fungal and bacterial diversity and assembly, community of deadwood inhabiting bacteria

This data are related to bacterial community composition in deadwood object.Project background1. Our forests are faced with an increasing demand for wood and threats caused by global change, forcing forest management into action. However, we still have important knowledge gaps on the ecological consequences of forest management in times of global change.2. Deadwood is recognized as a major contributor to the diversity of temperate forests. Forest management and natural disturbances create complex deadwood structures remaining in the forest after regular and salvage logging. Yet, the relative importance of these complex characteristics has not been quantified for fungal and bacterial diversity.3. Here, we experimentally simulated different deadwood types predominating after logging events to test their relative importance on bacterial and fungal diversity and assembly processes using metabarcoding, fruit body inventories, and Hill numbers: (i) log residues with soil contact resembling fallen logs or stumps, (ii) uplifted objects without soil contact resembling snags, uprooted logs, or deadwood in the tree canopy, (iii) barked deadwood, e.g., due to mechanical removal or abiotic and biotic effects (e.g., insects, sunburn), and (iv) those with intact bark. The deadwood was exposed under open versus closed canopies, resembling canopy disturbance and, thus, strong variation in microclimate conditions at the stand scale.4. Bark retention has stronger effects on microbial alpha and beta diversity than soil contact and stand-scale canopy. Debarking increases fungal and bacterial species diversity but decreases fungal fruiting diversity. Response of diversity due to bark retention was mainly similar under different stand scale canopies but not for fruiting diversity. Among treatments, debarking affected assembly processes most strongly. Communities within debarked wood are more dissimilar than expected, indicating limiting similarity as the dominant process explaining diverse communities. Deeper explorations revealed that differences in moisture conditions most probably caused the observed diversity patterns.5. Synthesis and applications: Our results showed that deadwood microbial diversity and assembly processes are primarily driven by object scale factors rather than stand scale canopy disturbance. Bark cover mediated by natural processes or by forest management techniques strongly affects microbial diversity and assembly processes through moisture change with suggested consequences on ecosystem functions like decomposition.