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This research explored the effects of the addition of low doses of aromatic plant biomasses (APBs) on the microbial community and carbon source decomposition in compost. APBs were reported to be capable of altering the composition and function of microbial communities in many environments. However, the effects of APB addition on the compost carbon source metabolism, a process highly linked to the microbial community of compost, were still unclarified, especially when added in small doses. In this study, Cinnamomum camphora biomass was added to the initial compost of Stropharia rugosoannulata cultivation materials, in a mass ratio of 0%, 1%, 2%, and 3%, respectively. The variation in the carbon source contents, the microbial community composition, and the related enzyme activities of the end compost products were measured. The results showed that Cinnamomum camphora biomass addition significantly altered the content of cellulose, hemicellulose, lignin, and protein of compost products, but did not affect the starch and soluble sugar content. Meanwhile, the addition significantly reduced lignin peroxidase and cellulase activities, but increased xylanase and laccase activities, and had no effect on magnesium peroxidase and polyphenol oxidase. Both the bacterial and fungal community compositions were significantly altered by the addition, though the alpha diversity indexes were not significantly changed. The relative abundance of Proteobacteria and Sordariomycetes was significantly increased by the addition, while Acidobacteria, Chloroflexi and Eurotiomycetes significantly decreased. Structural equation modeling found that the variation in the bacterial community composition (0.464 standard total effect) provided a higher contribution to lignocellulose degradation, rather than the fungal community (0.365 standard total effect). A co-occurrence network analysis further revealed that the trade-off between lignin peroxidase and laccase activity, which was induced by the relative abundance variation in Proteobacteria, Actinobacteriota, and Firmicute members, was the main driver in the lignocellulose decomposition variation. This research provides a new insight into the recycling of APB waste, and offers an improvement to mushroom cultivation material compost.

The increasing production of industrial aromatic plant residues (IAPRs) are potentially environmental risky, and composting is a promising solution to resolve the coming IAPR problems. Carbon source degradation is a basic but important field in compost research; however, we still lack a clear understanding of carbon source degradation and the corresponding relationship to microbial community variation during IAPR composting, which hampers the improvement of IAPR composting efficiency and the promotion of this technology. In this study, samples were chosen on the first day, the 10th day, the 20th day, and the last day during the composting of Cinnamomum camphora leaf IAPRs, and the microbial community composition, main carbon source composition, and several enzyme activities were measured accordingly. The results showed that during composting, the hemicellulose had the highest reduction (200 g kg−1), followed by cellulose (143 g kg−1), lignin (15.5 g kg−1), starch (5.48 g kg−1), and soluble sugar (0.56 g kg−1), which supported that hemicellulose and cellulose were the main carbon source to microbes during composting. The relative abundance of the main bacterial phylum Firmicute decreased from 85.1% to 40.3% while Actinobactreia increased from 14.4% to 36.7%, and the relative abundance of main fungal class Eurotiomycetes decreased from 60.9% to 19.6% while Sordariomycetes increased from 16.9% to 69.7%. Though principal coordinates analysis found that both bacterial and fungal community composition significantly varied during composting (p < 0.05), structure equation modeling (SEM) supported that bacterial composition rather than fungal counterpart was more responsible for the change in carbon source composition, as the standard total effects offered by bacterial composition (−0.768) was about five times the fungal composition (−0.144). Enzyme2 (comprised of xylanase, laccase, cellulase and manganese peroxidase) provided −0.801 standard total effects to carbon source composition, while Enzyme1 (comprised of lignin peroxidase and polyphenol oxidase) had only 0.172. Furthermore, xylanase and laccase were the only two enzymes appeared in co-occurrence network, clustered with nearly all the carbon sources concerned (except starch) in module-II. Xylanase, hemicellulose, and cellulose were linked to higher numbers of OTUs, more than laccase and other carbon sources. In addition, there were 11 BOTUs but only 1 FOTUs directly interacted to xylanase, hemicellulose, and cellulose simultaneously, three of them were Limnochordaceae and two were Savagea, which highlighted the potential core function in lignocellulose degradation provided by bacterial members, especially Limnochordaceae and Savagea. Thus, the results supported that during composting of Cinnamomum camphora leaf IAPRs, the degradation of dominate carbon sources, hemicellulose and cellulose, was mainly driven by bacterial community rather than fungal community. In addition, the bacterial originated xylanase and laccase played potentially core roles in the functional modules. This research clearly investigated the microbial dynamics of carbon source degradation during the composting of Cinnamomum camphora leaf IAPRs, and offers valuable information about and new insight into future IAPRs waste treatment.

Sarcandra glabra in-forest planting, an anthropogenic activity that may introduce a variety of disturbances into the forest, is being popularly promoted in southern China, while its consequential influences on soil nutrients, as well as the arbuscular mycorrhiza fungal (AMF) community of key forest keystone plants, are still unelucidated, which hampers the assessment of ecological safety and the improvement of agronomic measurements. In this research, topsoil from a 3-year-old Sarcandra glabra planted forest and a nearby control forest were sampled, and the annual variation in the soil nutrients and AMF community of the keystone tree Cunninghamia lanceolata were investigated. Our result showed that the total amount of soil organic carbon of the Sarcandra glabra cultivation group was significantly higher than that of the control group (p < 0.05), which indicated that Sarcandra glabra cultivation significantly enhanced the topsoil carbon storage. Yet, there were only insignificant differences in the Shannon index and Chao index of the AMF community between the two groups (p > 0.05). PCoA analysis found that the compositional differences between two groups were also insignificant. This indicated that Sarcandra glabra cultivation had no significant influence on the diversity and composition of the Cunninghamia lanceolata AMF community. However, we found that the differences in the total amounts of nitrogen and total phosphorus between the two groups were relatively lower in April and September, which indicated the higher nutrient demands and consumption of Sarcandra glabra in these two periods and suggested that a sufficient fertilizer application in these two stages would reduce the potential competition for nutrients between Sarcandra glabra and Cunninghamia lanceolata in order to ensure Sarcandra glabra production and forest health. Lastly, our results reported a total extra income ranging from of CNY 127,700 hm−2 (7 years of cultivation) to CNY 215,300 hm−2 (10 years cultivation) provided by Sarcandra glabra in-forest planting, which indicated its powerful potential for mitigating poverty. Our research systematically investigated the annual variation in the soil nutrient content and keystone tree AMF community caused by Sarcandra glabra cultivation and offers constructive guidance for Sarcandra glabra cultivation and fertilization management and ecological safety assessment.

The biodiversity of fungi, which are extremely important in maintaining the ecosystem balance in alpine lakeside wetlands, has not been fully studied. In this study, we investigated the fungal communities of three lakeside wetlands from different altitudes in the Qinghai&ndash, Tibet Plateau and its edge. The results showed that the fungi of the alpine lakeside wetland had higher species diversity. Functional annotation of fungi by FUNGild software showed that saprophytic fungi were the most abundant type in all three wetlands. Further analysis of the microbial phylogenetic molecular ecological network (pMEN) showed that saprophytic fungi are important species in the three wetland fungal networks, while symbiotic fungi and pathotrophic fungi have different roles in the fungal networks in different wetlands. Community diversity was high in all three lakeside wetlands, but there were significant differences in the composition, function and network structure of the fungal communities. Contemporary environmental conditions (soil properties) and historical contingencies (geographic sampling location) jointly determine fungi community diversity in this study. These results expand our knowledge of fungal biodiversity in the alpine lakeside wetlands.