Microbial diversity plays a crucial role in litter decomposition. However, the relationships between microbial diversity and substrate successional stage are the drivers of this decomposition. In this study, we experimentally manipulated microbial diversity and succession in post-mining soil. We used leaf litter samples from two forests of a post-mining site near Sokolov, Czech Republic: one alder plantation and one mixed forest with birch aspen and willow. Litter from each site was decomposed in the field for 3 and 12 months. The litter was X-ray sterilized and part of the litter was kept unsterilized to produce inoculum. Leaf litter samples of two different ages (3 and 12 months) from each site were each inoculated with litter of two different ages (3 and 12 months), using less and more diluted inoculum, producing two levels of microbial diversity. In each of these eight treatments, the bacterial community was then characterized by amplicon sequencing of the 16S rRNA gene and microbial respiration was used to assess the rate of decomposition. A significantly higher respiration (p < 0.05) was found for the litter inoculated with the higher level of microbial diversity. Higher respiration was also found for the younger litter compared to the older litter and both litter origins. This shows a reduction in microbial respiration with substrate age and inoculation diversity, suggesting that microbial diversity supports the decomposition of soil organic matter.

• Klíčová slova
• bacteria, decomposition of soil organic matter, fungi, microbial biomass, microbial diversity, succession,
• Publikační typ
• časopisecké články MeSH

Microbial diversity plays an important role in the decomposition of soil organic matter. However, the pattern and drivers of the relationship between microbial diversity and decomposition remain unclear. In this study, we followed the decomposition of organic matter in soils where microbial diversity was experimentally manipulated. To produce a gradient of microbial diversity, we used soil samples at two sites of the same chronosequence after brown coal mining in Sokolov, Czech Republic. Soils were X-ray sterilized and inoculated by two densities of inoculum from both soils and planted with seeds of six local plant species. This created two soils each with four levels of microbial diversity characterized by next-generation sequencing. These eight soils were supplied, or not, by litter of the bushgrass Calamagrostis epigejos, and microbial respiration was measured to assess the rate of decomposition. A strong positive correlation was found between microbial diversity and decomposition of organic matter per gram of carbon in soil, which suggests that microbial diversity supports decomposition if the microbial community is limited by available carbon. In contrast, microbial respiration per gram of soil negatively correlated with bacterial diversity and positively with fungal biomass, suggesting that in the absence of a carbon limitation, decomposition rate is controlled by the amount of fungal biomass. Soils with the addition of grass litter showed a priming effect in the initial stage of decomposition compared to the samples without the addition of litter. Thus, the relationship between microbial diversity and the rate of decomposition may be complex and context dependent.

• Klíčová slova
• carbon availability, decomposition of soil organic matter, fungal biomass, leaf litter, microbial biomass, microbial diversity,
• Publikační typ
• časopisecké články MeSH

Fine woody debris (FWD) represents the majority of the deadwood stock in managed forests and serves as an important biodiversity hotspot and refuge for many organisms, including deadwood fungi. Wood decomposition in forests, representing an important input of nutrients into forest soils, is mainly driven by fungal communities that undergo continuous changes during deadwood decomposition. However, while the assembly processes of fungal communities in long-lasting coarse woody debris have been repeatedly explored, similar information for the more ephemeral habitat of fine deadwood is missing. Here, we followed the fate of FWD of Fagus sylvatica and Abies alba in a Central European forest to describe the assembly and diversity patterns of fungal communities over 6 years. Importantly, the effect of microclimate on deadwood properties and fungal communities was addressed by comparing FWD decomposition in closed forests and under open canopies because the large surface-to-volume ratio of FWD makes it highly sensitive to temperature and moisture fluctuations. Indeed, fungal biomass increases and pH decreases were significantly higher in FWD under closed canopy in the initial stages of decomposition indicating higher fungal activity and hence decay processes. The assembly patterns of the fungal community were strongly affected by both tree species and microclimatic conditions. The communities in the open/closed canopies and in each tree species were different throughout the whole succession with only limited convergence in time in terms of both species and ecological guild composition. Decomposition under the open canopy was characterized by high sample-to-sample variability, showing the diversification of fungal resources. Tree species-specific fungi were detected among the abundant species mostly during the initial decomposition, whereas fungi associated with certain canopy cover treatments were present evenly during decomposition. The species diversity of forest stands and the variability in microclimatic conditions both promote the diversity of fine woody debris fungi in a forest.

• Klíčová slova
• canopy cover, deadwood, decomposition, ecology, fungal community, microclimate, succession, temperate forest,
• Publikační typ
• časopisecké články MeSH