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Background and aims: Wildfire is a primary driver of forest ecosystem functioning, and fire-induced changes in nutrient cycling and the balance of multiple nutrients may influence plant growth response to burning. However, the relationship between total and available soil stoichiometry and stoichiometric effects on the growth of fine roots following forest fires remain unclear. Methods: We measured the total and available soil C, N, and P concentrations, their ratios, and fine root biomass (FRB) at unburned control, 1-year-postfire, and 11-year-postfire sites in a Chinese boreal larch forest. We analyzed the relationship between soil stoichiometry and FRB. Results: Wildfire significantly reduced the total and available soil C:N:P ratios and FRB immediately postfire. Eleven years postfire, most indicators recovered to the prefire levels except for total soil C:P and N:P ratios, and available C:N ratio. Wildfire increased the associations between total and available soil C:N:P ratios, as well as between FRB and soil C:N:P ratios, but reduced the relationship between FRB and soil nutrient supply. However, these effects became weaker over time. Conclusions: The effects of wildfire on biogeochemical processes in boreal ecosystems extend to the relationship between total and available soil stoichiometry. Wildfires strengthen the linkage between fine roots and soil stoichiometry but weaken the effects of soil nutrient supply in the Great Xing'an Mountains. Therefore, the effects of wildfire on the coupling of soil C, N, and P cycling can produce a more complex soil-plant interaction in the early succession stage of boreal larch forest. [ABSTRACT FROM AUTHOR]

Microbial degradation of fluorinated compounds raised significant attention because of their widespread distribution and potential environmental impacts. Here, we report a bacterial isolate, Rhodococcus sp. NJF-7 capable of defluorinating monofluorinated medium-chain length alkanes. This isolate consumed 2.29 ± 0.13 mmol L− 1 of 1-fluorodecane (FD) during a 52 h incubation period, resulting in a significant release of inorganic fluoride amounting to 2.16 ± 0.03 mmol L− 1. The defluorination process was strongly affected by the initial FD concentration and pH conditions, with lower pH increasing fluoride toxicity to bacterial cells and inhibiting enzymatic defluorination activity. Stoichiometric conversion of FD to fluoride was observed at neutral pH with resting cells, while defluorination was significantly lower at reduced pH (6.5). The discovery of the metabolites decanoic acid and methyl decanoate suggests that the initial attack by monooxygenases may be responsible for the biological defluorination of FD. The findings here provide new insights into microbial defluorination processes, specifically aiding in understanding the environmental fate of organic semi-fluorinated alkane chemicals. [ABSTRACT FROM AUTHOR]

Aims: The effects of shrub encroachment on plant and soil properties have been well studied. However, little is known about how shrub encroachment influences soil bacterial communities. We investigated the effects of shrub encroachment on grassland soil bacterial communities along a soil depth gradient in the Inner Mongolian region of China.Methods: The belowground bacterial communities were examined using high-throughput sequencing of the 16S rRNA gene (V4-V5 region, Illumina MiSeq).Results: Bacterial alpha-diversity was higher in shrub-encroached soils than in control grassland soils. Bacterial OTU richness was highest at 0-20 cm soil depths, while phylogenetic diversity was greatest at 10-20 cm soil depths. At each soil depth layer, shrub encroachment was associated with a significant shift in bacterial community composition. Change in soil pH was the factor most strongly related to change in bacterial community composition associated with shrub encroachment at all four depth horizons in the soils. Shrub encroachment appears to alter the distribution of bacterial life history strategies in the surface soil (i.e., showing an enrichment in copiotrophs and a depletion in oligotrophs) and shrubs are associated with an increase in nitrification potential in deeper soil horizons.Conclusions: Our results indicate that the influence of shrub encroachment on bacterial community composition extends deep into the soil. The intensity of shrub encroachment at this study site suggests that this ecosystem is undergoing dramatic succession towards shrub-dominance, which will likely trigger shifts in ecosystem function. [ABSTRACT FROM AUTHOR]

The alpine meadow on the Qinghai-Tibetan Plateau (QTP), which is sensitive to global climate change and human activities, is subjected to addition of nutrients such as nitrogen (N) and phosphorus (P) in the soil. The impacts of N or P on ecosystem structure and function depend at least partly on the response of soil fungal communities, although few studies have compared the effects of N and P addition, both separately and together. We examined the responses of composition of the soil fungal community to 3-year experimental nutrient additions (control, N, N plus P, and P) in a typical alpine meadow of the QTP. We found that P addition, regardless of N addition, significantly reduced fungal species richness and changed fungal community composition, while the effect of N was undetectable. Nitrogen plus phosphorus caused a more distinct community than either N or P addition alone. Multivariate regression tree, canonical correspondence analysis, and distance-based multivariate linear model analyses all suggested available P was a key parameter determining the diversity and composition of the fungal community. Other parameters such as dissolved organic N, aboveground net primary productivity of forbs, and dissolved organic C played important but secondary roles. The results indicated an important role of P in structuring soil fungal communities in the alpine meadow. Our results suggest that fungal diversity loss and long-term changes in ecosystem stability can result from fertilization management in the fragile alpine environment. [ABSTRACT FROM AUTHOR]

Aims: Wildfires are important disturbances that help to shape the structure and function of forest ecosystems, and arbuscular mycorrhizal fungi (AMF) are key players in the post-fire recovery of soils and understory vegetation. We aimed to investigate the response of AMF communities to wildfire over different timescales. Methods: Primer set AMV4.5NF/AMDGR was used to amplify soil 18S rRNA gene fragments for the 454 GS-FLX pyrosequencing platform to examine belowground AMF communities 1 and 11 years following low- and high-intensity wildfires in the Greater Khingan Mountains of China. Results: The majority of AMF sequences detected were annotated as Glomeraceae, Claroideoglomeraceae, Diversisporaceae and Acaulosporaceae. Both AMF community composition and alpha-diversity were correlated with herbaceous and shrubby biomass, available phosphorus (AP) and NH, which were in turn altered by wildfire. AMF community composition, alpha-diversity, and phylogenetic structure were significantly altered 1-year-post-fire. However, AMF communities were indistinguishable from unburned forest soils 11-year-post-fire. Conclusions: Our results indicated that AMF communities are resilient to wildfire on decadal timescales. This resilience appears to depend on the post-fire regrowth of understory vegetation and the subsequent recovery of soil chemical properties. [ABSTRACT FROM AUTHOR]

Stag beetles, recognized as common saproxylic insects, are valued for their vibrant coloration and distinctive morphology. These beetles play a crucial ecological role in decomposition and nutrient cycling, serving as a vital functional component in ecosystem functioning. Although previous studies have confirmed that stag beetles are predominantly fungivores, the fluctuations in their intestinal fungal communities at different developmental stages remain poorly understood. In the current study, high-throughput sequencing was employed to investigate the dynamic changes within intestinal fungal communities at various developmental stages in the stag beetle Dorcus hopei. Results showed that microbial diversity was higher during the larval stage than during the pupal and adult stages. Furthermore, significant differences were identified in the composition of the intestinal fungal communities across the larval, pupal, and adult stages, suggesting that developmental transitions may be crucial factors contributing to variations in fungal community composition and diversity. Dominant genera included Candida, Scheffersomyces, Phaeoacremonium, and Trichosporon. Functional predictions indicated a greater diversity and relative abundance of endosymbiotic fungi in the larval gut, suggesting a potential dependency of larvae on beneficial gut fungi for nutrient acquisition. Additionally, the application of abundance-based β-null deviation and niche width analyses revealed that the adult gut exerted a stronger selection pressure on its fungal community, favoring certain taxa. This selection process culminates in a more robust co-occurrence network of fungal communities within the adult gut, thereby enhancing their adaptability to environmental fluctuations. This study advances our understanding of the intestinal fungal community structure in stag beetles, providing a crucial theoretical foundation for the development of saproxylic beetle resources, biomass energy utilization, plastic degradation strategies, and beetle conservation efforts. [ABSTRACT FROM AUTHOR]