Struktura a funkce bakteriálních společenstev v průběhu sukcese na odumřelé rostlinné biomase

Rozklad odumřelé rostlinné biomasy se významnou měrou podílí na koloběhu uhlíku a je tak jedním z klíčových procesů probíhajících v lesích mírného pásu. Zatímco role hub při rozkladu opadu a dřeva byla opakovaně zkoumána, jen málo studií se zabývalo bakteriemi asociovanými s rozkládající se rostlinnou biomasou. Vývoj bakteriálního společenstva asociovaného se stromovým opadem je pravděpodobně způsoben změnami v chemickém složení opadu a dostupností živin. Aktivita hub značně přispívá ke změnám v substrátu a tím je ovlivněno také bakteriální společenstvo. Dostupnost živin se mění v průběhu rozkladu biomasy, na počátku jsou snadno dostupné lehce rozložitelné látky, zatímco později jsou rozkládány odolnější sloučeniny (např. lignin). Bakteriální kolonizace mrtvého dřeva je ovlivněna řadou faktorů, jako například místně specifické klimatické podmínky, druh stromu, objem dřeva. Cílem této práce bylo popsat dynamiku bakteriálního společenstva během dvouletého rozkladu stromového opadu a odumřelého dřeva. V opadovém experimentu bylo bakteriální společenstvo analyzováno v živých, odumírajících a rozkládajících se listech dubu zimního (Quercus petraea). Experiment probíhal v přírodní památce Xaverovský háj v České republice. Experiment s odumřelým dřevem byl zaměřen na složení bakteriálního společenstva v...The decomposition of dead plant biomass substantially contributes to the carbon cycle and therefore is one of the key processes in temperate forests. While the role of fungi in litter and deadwood decomposition was repeatedly addressed, there are just a few surveys of bacteria associated with decomposing plant biomass. The development of bacterial community within leaf litter is likely driven by the changes in litter chemistry and by the availability of nutrients in the litter. Fungal activity greatly contributes to changing properties of substrate and thus influences bacterial community. Availability of nutrients is changing during biomass decomposition from easily accessible substrates toward more recalcitrant ones (e.g. lignin). The colonization of deadwood by bacteria is influenced by various factors such as microclimate conditions, tree species and volume. The aim of this thesis was to describe bacterial community dynamics during the first two years of decomposition of leaf litter and deadwood. In the leaf litter experiment, bacterial community was analysed in the live, senescent and decomposing leaves of Quercus petraea. This experiment was performed in the Xaverovsky Haj Natural Reserve, Czech Republic. Deadwood experiment was focused on the composition of bacterial community in the initial...Department of Genetics and MicrobiologyKatedra genetiky a mikrobiologiePřírodovědecká fakultaFaculty of Scienc

Bacteria associated with decomposing deadwood

Deadwood is a hotspot of microbial diversity and its decomposition contributes to carbon and nitrogen cycling in temperate forests. The historically recognized importance of fungi in the decomposition of deadwood has recently been complemented by the description of bacterial functions thanks to the rapid progress of culture-independent methods based on the analysis of nucleic acids. To study different aspects of deadwood decomposition, a temperate mixed forest in Zofinsky prales National Nature Reserve was selected as a site with rich historical forestry data where deadwood decomposition represents an important process in wood turnover. The aim of this thesis is to describe role of bacteria in deadwood decomposition at fine scale resolution with respect to community composition, enzyme transcription, and metabolic potential of dominant species. Effects of deadwood age together with pH and water content on the bacterial community composition proved to be more important than tree species identity. Bacteria showed distinct composition between early and late community in decomposing deadwood. The bacterial community was also under a significant influence of fungal community composition. Despite being in a close contact, bacterial and fungal communities differed significantly between deadwood and the..

Successional Development of Fungal Communities Associated with Decomposing Deadwood in a Natural Mixed Temperate Forest

Deadwood represents an important carbon stock and contributes to climate change mitigation. Wood decomposition is mainly driven by fungal communities. Their composition is known to change during decomposition, but it is unclear how environmental factors such as wood chemistry affect these successional patterns through their effects on dominant fungal taxa. We analysed the deadwood of Fagus sylvatica and Abies alba across a deadwood succession series of >40 years in a natural fir-beech forest in the Czech Republic to describe the successional changes in fungal communities, fungal abundance and enzymatic activities and to link these changes to environmental variables. The fungal communities showed high levels of spatial variability and beta diversity. In young deadwood, fungal communities showed higher similarity among tree species, and fungi were generally less abundant, less diverse and less active than in older deadwood. pH and the carbon to nitrogen ratio (C/N) were the best predictors of the fungal community composition, and they affected the abundance of half of the dominant fungal taxa. The relative abundance of most of the dominant taxa tended to increase with increasing pH or C/N, possibly indicating that acidification and atmospheric N deposition may shift the community composition towards species that are currently less dominant

Primary determinants of communities in deadwood vary among taxa but are regionally consistent

The evolutionary split between gymnosperms and angiosperms has far‐reaching implications for the current communities colonizing trees. The inherent characteristics of dead wood include its role as a spatially scattered habitat of plant tissue, transient in time. Thus, local assemblages in deadwood forming a food web in a necrobiome should be affected not only by dispersal ability but also by host tree identity, the decay stage and local abiotic conditions. However, experiments simultaneously manipulating these potential community drivers in deadwood are lacking. To disentangle the importance of spatial distance and microclimate, as well as host identity and decay stage as drivers of local assemblages, we conducted two consecutive experiments, a 2‐tree species and 6‐tree species experiment with 80 and 72 tree logs, respectively, located in canopy openings and under closed canopies of a montane and a lowland forest. We sampled saproxylic beetles, spiders, fungi and bacterial assemblages from logs. Variation partitioning for community metrics based on a unified framework of Hill numbers showed consistent results for both studies: host identity was most important for sporocarp‐detected fungal assemblages, decay stage and host tree for DNA‐detected fungal assemblages, microclimate and decay stage for beetles and spiders and decay stage for bacteria. Spatial distance was of minor importance for most taxa but showed the strongest effects for arthropods. The contrasting patterns among the taxa highlight the need for multi‐taxon analyses in identifying the importance of abiotic and biotic drivers of community composition. Moreover, the consistent finding of microclimate as the primary driver for saproxylic beetles compared to host identity shows, for the first time that existing evolutionary host adaptions can be outcompeted by local climate conditions in deadwood

A meta-analysis of global fungal distribution reveals climate-driven patterns

The evolutionary and environmental factors that shape fungal biogeography are incompletely understood. Here, we assemble a large dataset consisting of previously generated mycobiome data linked to specific geographical locations across the world. We use this dataset to describe the distribution of fungal taxa and to look for correlations with different environmental factors such as climate, soil and vegetation variables. Our meta-study identifies climate as an important driver of different aspects of fungal biogeography, including the global distribution of common fungi as well as the composition and diversity of fungal communities. In our analysis, fungal diversity is concentrated at high latitudes, in contrast with the opposite pattern previously shown for plants and other organisms. Mycorrhizal fungi appear to have narrower climatic tolerances than pathogenic fungi. We speculate that climate change could affect ecosystem functioning because of the narrow climatic tolerances of key fungal taxa.This article is published as Větrovský, Tomáš, Petr Kohout, Martin Kopecký, Antonin Machac, Matěj Man, Barbara Doreen Bahnmann, Vendula Brabcová et al. "A meta-analysis of global fungal distribution reveals climate-driven patterns." Nature Communications 10, no. 1 (2019): 1-9. DOI: 10.1038/s41467-019-13164-8. Posted with permission.</p

A meta-analysis of global fungal distribution reveals climate-driven patterns.

The evolutionary and environmental factors that shape fungal biogeography are incompletely understood. Here, we assemble a large dataset consisting of previously generated mycobiome data linked to specific geographical locations across the world. We use this dataset to describe the distribution of fungal taxa and to look for correlations with different environmental factors such as climate, soil and vegetation variables. Our meta-study identifies climate as an important driver of different aspects of fungal biogeography, including the global distribution of common fungi as well as the composition and diversity of fungal communities. In our analysis, fungal diversity is concentrated at high latitudes, in contrast with the opposite pattern previously shown for plants and other organisms. Mycorrhizal fungi appear to have narrower climatic tolerances than pathogenic fungi. We speculate that climate change could affect ecosystem functioning because of the narrow climatic tolerances of key fungal taxa