Soil Fungal Community Structure Research Articles

Forest Type and Climate Outweigh Soil Bank in Shaping Dynamic Changes in Macrofungal Diversity in the Ancient Tree Park of Northeast China.

The community structure of macrofungi is influenced by multiple complex factors, including climate, soil, vegetation, and human activities, making it challenging to discern their individual contributions. To investigate the dynamic changes in macrofungal diversity in an Ancient Tree Park located in Northeast China and explore the factors influencing this change, we collected 1007 macrofungi specimens from different habitats within the park and identified 210 distinct fungal species using morphological characteristics and ITS sequencing. The species were classified into 2 phyla, 6 classes, 18 orders, 55 families, and 94 genera. We found macrofungal compositions among different forest types, with the mixed forest displaying the highest richness and diversity. Climatic factors, particularly rainfall and temperature, positively influenced macrofungal species richness and abundance. Additionally, by analyzing the soil fungal community structure and comparing aboveground macrofungi with soil fungi in this small-scale survey, we found that the soil fungal bank is not the main factor leading to changes in the macrofungal community structure, as compared to the influence of climate factors and forest types. Our findings provide valuable insights into the dynamic nature of macrofungal diversity in the Ancient Tree Park, highlighting the influence of climate and forest type.

Effects of afforestation on soil fungi in rocky mountain areas of North China

AbstractAfforestation has a substantial influence on soil fungal communities by introducing ecological variations within forest ecosystems via the inclusion of distinct tree species (coniferous and broadleaf) and afforestation patterns (pure forests and mixed forests). However, the specific effects of these variations on soil fungal communities require further investigation. Soil samples from birch (B: Betula platyphylla Suk.), larch (L: Larix gmelinii (Rupr.) Kuzen.), and mixed birch and larch (B–L) forests were used in this study, and a shrub–grassland field (S–G) was used as a reference. The abundance, diversity, and community composition of fungi in the soil of the monoculture forest (B and L), mixed forest (B–L), and S–G were studied by high‐throughput sequencing. The results showed that Basidiomycota was the dominant fungus in B and B–L, and the dominant genera were Inocybe and Amanita, respectively. Ascomycota was the dominant fungus in L and S–G, and the dominant genus was Mortierella. Afforestation reduced the richness and diversity of soil fungi. Larch forests were richer in soil fungi than B and B–L forests. Soil organic carbon was the main soil factor affecting the soil fungal community structure. Soil fungal community network changed less after planting L than after planting B and B–L, and the soil fungal community structure was more complex and stable in L than in B and B–L. For soil fungal community composition and function, mixed forests did not show outstanding advantages. Planting monoculture forests may be a more effective afforestation strategy in the rocky mountain areas of North China.

The Preliminary Research on Shifts in Maize Rhizosphere Soil Microbial Communities and Symbiotic Networks under Different Fertilizer Sources

The use of chemical fertilizer along with organic fertilizer is an important agricultural practice that improves crop yield but also affects soil biogeochemical cycles. In this study, a maize field experiment was conducted to investigate the effects of NPK fertilizer (NPK), organic fertilizer (OF), and their combination (NPK+OF) on soil chemical properties, bacterial and fungal community structures, and diversity compared the control (CK, without any fertilizer). The results showed that the application of OF and NPK-combined OF increased soil organic matter (OM), total N, total P, available N, available P, and available K levels. For alpha diversity analyses, the application of fertilizers led to decreases in soil bacterial and fungal Shannon indices (except for NPK in fungi). Compared with CK, NPK, OF, and NPK+OF fertilization treatments significantly increased the abundances of Acidobacteriota, Gemmatimonadota, and Basidiomycota. Network analysis showed that fertilization produced fewer connections among microbial taxa, especially in the combination of NPK and OF. A redundancy analysis combined with Mantel test further found that the soil OM, available N and P were the main soil-fertility factors driving microbial community variations. Therefore, using organic fertilizer or biological fertilizer combined with chemical fertilizer to improve the status of soil C, N, and P is a promising method to maintain the balance of soil microorganisms in maize field.

Impact of Coexistence of Microplastics and Biochar on the Abundance and Structure of Soil Fungal Communities

In this pursuit, we analyzed the effects of microplastics (PP, PE, PVC) and microplastics and biochar coexistence (PPR, PER, PVCR) on soil fungal community structure and diversity, and functional prediction analysis. Results showed that microplastics and their coexistence with biochar had a significant impact on the soil physicochemical, with PVCR treatment exhibiting the highest soil pH, organic carbon, phosphorus, potassium, and ammonium nitrogen content. Microplastics and their coexistence with biochar significantly increased fungal abundance, with PPR treatment having the highest fungal abundance. Microplastics and their coexistence with biochar (except for PP) significantly reduced the soil fungal diversity indices. The dominant fungal communities were Ascomycota, Basidiomycota, and Zygomycota, while at the genus level, Mortierella, Aspergillus, and Fusarium were found to be dominant taxa. Microplastics and their coexistence with biochar promoted the Basidiomycota and Mortierella and inhibited the Ascomycota and Fusarium. Effect of microplastics and biochar coexistence was significantly higher than that of microplastics alone. Soil pH, ammonium nitrogen, organic carbon, nitrate nitrogen, and potassium were main factors affecting the soil fungal community structure changes. FUNGuild functional prediction results showed that microplastics and their coexistence with biochar had a significant influence on the functional group. The relative abundance of pathogenic-saprotrophic-symbiotic nutritional fungi was the highest in the PPR while the PVCR showed the highest relative abundance of saprotrophic nutritional fungi. In summary, the coexistence of microplastics and biochar had a significant affect the soil fungal community, while its impact exhibited variations depending on the type of microplastics.

Effects of Bacillus velezensis GUAL210 control on edible rose black spot disease and soil fungal community structure.

Rose black spot is an economically important disease that significantly decreases flower yield. Fungicide and biological control are effective approaches for controlling rose black spot. The objective of this study was to evaluate the effect of application of biological and chemical control agents, including Bacillus velezensis (GUAL210), Bacillus sp. (LKW) and fungicide (CP) on the black spot disease and rhizosphere fungal community structure of edible rose. In this study, the R. chinensis 'Crimson Glory' was taken as the research object, and the field experiment was designed by randomized block design. The experiment contained 3 treatments (CP, GUAL210, LKW) and 1 control. The control effect and growth promoting effect of fungicide and biological control on rose black spot were compared. The composition and diversity of rhizosphere soil fungal community of different treatments of rose were studied by high-throughput sequencing method. The fungal community composition, correlation of environmental factors and differences in metabolic pathways related to rose disease were analyzed, and the correlation between rhizosphere soil fungal community of rose and biological control of disease was explored. Both disease incidence and disease index differed significantly among groups (LKW < GUAL210 < CP < CK), and disease control effect exhibited no significant difference between GUAL210 and LKW (60.96% and 63.86%, respectively). Biological control was superior to chemical control in terms of disease prevention effects and duration, and it significantly increased the number of branches and flowers of rose plants. Ascomycota and Basidiomycota accounted for more than 74% of the total fungal abundance, and the abundance of Ascomycota was highest in CK, followed by GUAL210, CP and LKW, which was consistent with the disease occurrence in each group. The analysis of metabolic pathways showed that the HSERMETANA-PWY in each experimental group was significantly lower than that in control group. The Shannon index in each experimental group was significantly lower than that in control group. PCoA analysis showed that the rhizosphere fungal community structure in each experimental group was significantly different from that in control group. Trichoderma, Paraphaeosphaeria, Suillus, Umbelopsis in GUAL210, and Galerina in LKW replaced Mortierella, Pestalotiopsis, Ustilaginoidea, Paraconiothyrium, Fusarium, and Alternaria as dominant flora, and played a nonneglectable role in reducing disease occurrence. The difference in rhizosphere fungal community structure had an important impact on the incidence of rose black spot disease. Biological control is crucial for establishing environment-friendly ecological agriculture. GUAL210 has promising prospects for application and development, and may be a good substitute for chemical control agents.

Differences in cover cropping management affect soil nitrogen, carbon characteristics, and fungal community composition in a vineyard in North China

Cover cropping is widely used for soil management in vineyards. But few studies have compared the effect of different cover cropping management methods on soil properties and fungal communities in vineyards. Therefore, we examined the effects of traditional management (shallow tillage to remove weeds), cover with single species (two treatments covered with different herbages), cover with mixed species (two combination treatments named M1 and M2 respectively), and cover with a crop on soil physicochemical properties and fungal community structure in a vineyard in northern China in 2020 and 2021. Soil total carbon and mineral nitrogen increased under Carex lanceolata Boott, Medicago sativa L., M1, and M2 covers but decreased under Glycine max (L.) Merr. Compare to traditional management. Soil organic carbon content increased under Carex lanceolata Boott, Medicago sativa L., M1, and M2, with increasing planting time. Cover cropping management had a minor effect on fungal diversity in the short term. Effects on beneficial and pathogenic fungi varied with cover type. With a cover of Glycine max (L.) Merr, the abundance of Fusarium brachygibbosum, a pathogen that affects grape production, increased, but that of Chaetomium, a genus that inhibits pathogens, also increased. With a cover of Carex lanceolata Boott, the abundance of Didymella glomerata, another pathogen that affects grape production, increased, but that of Metarhizium, an entomopathogenic fungus, also increased. Compared with Carex lanceolata Boott, covers with mixed species (M1 and M2) showed minor effects on soil pathogens, so covers with mixed species could benefit the vineyards more than other cover cropping management in North China.

Mechanisms by which chloropicrin fumigation promotes soil potassium conversion and absorption.

Fumigation of soil using chloropicrin has been proven to significantly affect soil nutrient cycling, but the mechanism by which soil potassium conversion and plant uptake is promoted remains unclear. In this study, we conducted a fumigation experiment to investigate the effects of chloropicrin soil fumigation on the conversion of soil potassium post-fumigation (days 7-70), and its mechanisms, tomatos were planted in fumigated and non-fumigated soils to enable further comparisons. Results showed that the content of rapidly available potassium and available potassium decreased by 16-24% and 17-23% at day 28 respectively, when tomato was planted in chloropicrin-fumigated soils compared to the non-fumigated soils. The potassium content of tomato planted in fumigated soil was significantly higher than that planted in non-fumigated soil (30.3 vs. 21.9 mg g-1 dry weight). Chloropicrin fumigation resulted in a significant change in the soil bacterial and fungal community structures, and trigged a long-term (at least 70-day) decrease in microbial diversity. Network analysis showed that chloropicrin soil fumigation changed microbial co-occurrence patterns by decreasing bacterial total links, nodes, and average degree, and increasing fungal total links, nodes, and average degree. Chloropicrin fumigation caused significant changes in the relative abundance of Bacillus species, which are involved in potassium dissolution. Structural equation model (SEM) suggested that fumigation with chloropicrin enhanced the contribution of soil potassium to tomato growth and reduced the contribution of bacterial communities. Together, the results of our study help in understanding the crop yield enhancement mechanism of soil fumigation.

The effect of seed bacterization with Bacillus paralicheniformis 2R5 on bacterial and fungal communities in the canola rhizosphere

Bacillus sp. is one of the best-studied plant growth-promoting rhizobacteria (PGPR). However, more detailed studies targeting its effect on the rhizosphere microbial community are required for improving management practices regarding its commercial application in the field. Our earlier study showed that PGPR Bacillus paralicheniformis 2R5 stimulated canola growth. Hence, this study aimed to assess the time-course impact of B. paralicheniformis 2R5 on bacterial and fungal community structure and diversity. The results showed that inoculation with B. paralicheniformis 2R5 initially significantly decreased the observed bacterial richness compared to the control, while after 44 days of treatment this alpha diversity metrics increased. A linear discriminant analysis effect size showed that B. paralicheniformis 2R5 altered the soil bacterial and fungal community structure by increasing the abundance of plants’ beneficial microorganisms such as Nitrospira, Ramlibacter, Sphingomonas, Massilia, Terrimonas as well as Solicoccozyma, Schizothecium, Cyphellophora, Fusicolla, Humicola. B. paralicheniformis 2R5 seems to be a promising alternative to chemical pesticides and can be considered for practical application in the field. Its ability to alter the rhizosphere microbiome by increasing the diversity and composition of bacterial communities and increasing plants’ beneficial groups of fungi, appears to be important in terms of improving canola development. However, further studies on these increased microbial taxa are necessary to confirm their function in promoting canola growth.

Effects of warming and nitrogen addition on soil fungal and bacterial community structures in a temperate meadow.

Soil microbial communities have been influenced by global changes, which might negatively regulate aboveground communities and affect nutrient resource cycling. However, the influence of warming and nitrogen (N) addition and their combined effects on soil microbial community composition and structure are still not well understood. To explore the effect of warming and N addition on the composition and structure of soil microbial communities, a five-year field experiment was conducted in a temperate meadow. We examined the responses of soil fungal and bacterial community compositions and structures to warming and N addition using ITS gene and 16S rRNA gene MiSeq sequencing methods, respectively. Warming and N addition not only increased the diversity of soil fungal species but also affected the soil fungal community structure. Warming and N addition caused significant declines in soil bacterial richness but had few impacts on bacterial community structure. The changes in plant species richness affected the soil fungal community structure, while the changes in plant cover also affected the bacterial community structure. The response of the soil bacterial community structure to warming and N addition was lower than that of the fungal community structure. Our results highlight that the influence of global changes on soil fungal and bacterial community structures might be different, and which also might be determined, to some extent, by plant community, soil physicochemical properties, and climate characteristics at the regional scale.

Habitat ecological characteristics and soil fungal community structure of Paphiopedilum subgenus Brachypetalum Hallier (Orchidaceae) plants in Southwest China

ABSTRACT Species of the subgenus Brachypetalum are the most primitive, most ornamental and most threatened group in the Orchid. This study revealed the ecological characteristics, soil nutrient characteristics and soil fungal community structure of habitats of the subgenus Brachypetalum in Southwest China. Lays a foundation for research on the wild populations and conservation Brachypetalum. The results showed that species of the subgenus Brachypetalum preferred a cool and humid environment, grew in scattered or aggregated form in narrow negative terrain, mainly in humic soil. The soil physical and chemical properties and soil enzyme activity indexes of the habitats were significantly different among different species, and the soil properties of different distribution points of the same species also varied greatly. There were significant differences in the soil fungal community structure among the habitats of different species. Basidiomycetes and ascomycetes were the main fungi in habitats of subgenus Brachypetalum species, and their relative abundance varied among different species. The functional groups of soil fungi were mainly symbiotic fungi and saprophytic fungi. LEfSe analysis found that there were different numbers and species of biomarkers in the habitats of subgenus Brachypetalum species, indicating that the habitat preference characteristics of each species in subgenus Brachypetalum were reflected in the fungal community. It was found that environmental factors had an impact on the changes in soil fungal communities in the habitats of subgenus Brachypetalum species, with climatic factors having the highest explanation rate (20.96%). Soil properties were significantly positively or negatively correlated with a variety of dominant soil fungal groups. Conclusions: The results of this study lay the foundation for the study of the habitat characteristics of wild populations of subgenus Brachypetalum and provides data to support in situ and ex situ conservation in the future.

Effects of wood ash on the soil properties and fungal community structure in a beech forest in Poland

The aim of this study was to determine how wood-ash fertilization affects the basic properties of soil, including the pH and the carbon (C), nitrogen (N) and phosphorus stoichiometric, and, consequently, the microbial activity, including the abundance and composition of the soil fungi. The studied plots were amended using 3, 4.5 and 6 t of wood ash per hectare, with control plots with no added wood ash also being designated. Analyses of the main physicochemical properties of the soils, enzymatic activity and microbial biomass of C and N were performed two years after the addition of the wood ash. The fungal communities were investigated using next-generation sequencing technology. We found that the use of wood ash increased the soil pH over a short time, with the highest dose having the strongest effect, and increased the abundance of nutrients, which in turn increased the microbiological activity. The addition of wood ash to the soil was also important in shaping the composition of the fungi.

Effects of Different Planting Years of Dendrocalamus brandisii on Soil Fungal Community

To explore the effect of soil fungal community under different planting years in Dendrocalamus brandisii, the soil samples from D. brandisii with different planting years (5, 10, 20, and 40 a) were taken as the research object. The soil fungal community structure, diversity, and its functional groups of different planting years were analyzed using high-throughput sequencing technology and the FUNGuild fungal function prediction tool, and the main soil environmental factors influencing the variations in soil fungal community were examined. The results showed that the dominant fungal communities at the phylum level were Ascomycota, Basidiomycota, Mortierellomycota, and Mucoromycota. The relative abundance of Mortierellomycota decreased and then increased with the increase in planting years, and there was a significant difference among different planting years (P<0.05). The dominant fungal communities at the class level were Sordariomycetes, Agaricomycetes, Eurotiomycetes, and Mortierellomycetes. The relative abundance of Sordariomycetes and Dothideomycetes decreased and then increased with the increase in planting years, and there were significant differences among different planting years (P<0.01). The Richness index and Shannon index of soil fungi increased and then decreased with the increase in planting years, and the Richness index and Shannon index in 10 a were significantly higher than those of other planting years. Non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) showed that there were significant differences in soil fungal community structure with different planting years. The functional prediction with FUNGuild showed that the main functional trophic types of soil fungi in D. brandisii were pathotroph, symbiotroph, and saprotroph, and the most dominant functional group was endophyte-litter saprotroph-soil saprotroph-undefined saprotroph. The relative abundance of endophytes gradually increased with the increase in planting years. Correlation analysis showed that pH, total potassium (TK), and nitrate nitrogen (NO-3-N) were the main soil environmental factors affecting the change in fungal community. In summary, the planting year of D. brandisii has changed soil environmental factors and has thus changed the structure, diversity, and functional groups of soil fungal communities.

Effects of p-Hydroxyphenylacetic Acid and p-Hydroxybenzoic Acid on Soil Bacterial and Fungal Communities

Soil phenolic acids mainly come from crop residue and root exudates, which are often reported as allelochemicals affecting crop growth and soil microbial community. Here, two phenolic acid compounds, p-hydroxyphenylacetic acid (HPA) and p-hydroxybenzoic acid (HBA) were amended to the soils and were incubated under room conditions, and the soil samples were collected from soybean and corn fields separately. The soil microbial community was determined by PCR-DGGE (polymerase chain reaction-denatured gradient gel electrophoresis) and clone methods. Microbial biomass carbon (MBC) was measured based on the fumigation–extraction method. The result revealed that HPA/HBA amendment significantly affected soil bacterial and fungal community structures. HPA/HBA enriched some distinct bacteria and fungi. The induced bacteria were mainly Gemmatimonas, Bacillus, and Acidobacteria, while the induced fungi were mainly Penicillium and Aspergillus. HPA amendment enhanced the more bacterial quantities of corn and soybean soils than HBA. The fungal diversity in corn and soybean soils treated with HBA was higher than that treated with HPA. It was speculated that the diversity of degrading HBA fungi was higher than that of degrading HPA. This study comprehensively analyzed the effects of phenolic acids on soil microbial community and increased the understanding of the monoculture barrier to agricultural production.

Simulating the effect of climate change on soil microbial community in an Abies georgei var. smithii forest.

Qinghai-Tibet Plateau is considered a region vulnerable to the effects of climate change. Studying the effects of climate change on the structure and function of soil microbial communities will provide insight into the carbon cycle under climate change. However, to date, changes in the successional dynamics and stability of microbial communities under the combined effects of climate change (warming or cooling) remain unknown, which limits our ability to predict the consequences of future climate change. In this study, in situ soil columns of an Abies georgei var. smithii forest at 4,300 and 3,500 m elevation in the Sygera Mountains were incubated in pairs for 1 year using the PVC tube method to simulate climate warming and cooling, corresponding to a temperature change of ±4.7°C. Illumina HiSeq sequencing was applied to study alterations in soil bacterial and fungal communities of different soil layers. Results showed that warming did not significantly affect the fungal and bacterial diversity of the 0-10 cm soil layer, but the fungal and bacterial diversity of the 20-30 cm soil layer increased significantly after warming. Warming changed the structure of fungal and bacterial communities in all soil layers (0-10 cm, 10-20 cm, and 20-30 cm), and the effect increased with the increase of soil layers. Cooling had almost no significant effect on fungal and bacterial diversity in all soil layers. Cooling changed the structure of fungal communities in all soil layers, but it showed no significant effect on the structure of bacterial communities in all soil layers because fungi are more adapted than bacteria to environments with high soil water content (SWC) and low temperatures. Redundancy analysis (RDA) and hierarchical analysis showed that changes in soil bacterial community structure were primarily related to soil physical and chemical properties, whereas changes in soil fungal community structure primarily affected SWC and soil temperature (Soil Temp). The specialization ratio of fungi and bacteria increased with soil depth, and fungi were significantly higher than bacteria, indicating that climate change has a greater impact on microorganisms in deeper soil layers, and fungi are more sensitive to climate change. Furthermore, a warmer climate could create more ecological niches for microbial species to coexist and increase the strength of microbial interactions, whereas a cooler climate could have the opposite effect. However, we found differences in the intensity of microbial interactions in response to climate change in different soil layers. This study provides new insights to understand and predict future effects of climate change on soil microbes in alpine forest ecosystems.

Variations in soil microbial community structure and extracellular enzymatic activities along a forest-wetland ecotone in high-latitude permafrost regions.

Permafrost degradation by global warming is expected to alter the hydrological processes, which results in changes in vegetation species composition and gives rise to community succession. Ecotones are sensitive transition areas between ecosystem boundaries, attract particular interest due to their ecological importance and prompt responses to the environmental variables. However, the characteristics of soil microbial communities and extracellular enzymes along the forest-wetland ecotone in high-latitude permafrost region remain poorly understood. In this study, we evaluated the variations of soil bacterial and fungal community structures and soil extracellular enzymatic activities of 0-10 cm and 10-20 cm soil layers in five different wetland types along environmental gradients, including Larix gmelinii swamp (LY), Betula platyphylla swamp (BH), Alnus sibirica var. hirsute swamp (MCY), thicket swamp (GC), and tussock swamp (CC). The relative abundances of some dominant bacterial (Actinobacteria and Verrucomicrobia) and fungal (Ascomycota and Basidiomycota) phyla differed significantly among different wetlands, while bacterial and fungal alpha diversity was not strongly affected by soil depth. PCoA results showed that vegetation type, rather than soil depth explained more variation of soil microbial community structure. β-glucosidase and β-N-acetylglucosaminidase activities were significantly lower in GC and CC than in LY, BH, and MCY, while acid phosphatase activity was significantly higher in BH and GC than LY and CC. Altogether, the data suggest that soil moisture content (SMC) was the most important environmental factor contributing to the bacterial and fungal communities, while extracellular enzymatic activities were closely related to soil total organic carbon (TOC), nitrate nitrogen () and total phosphorus (TP).

Variations in litter-soil properties between planted and naturally restored forests drive microbial community structure and function

How forest restoration can affect soil microbial composition and functionality remains unclear, limiting our ability to evaluate restoration approaches. Here, we used metagenomes, 16S rRNA, and ITS gene sequencing to distinguish the composition and functional attributes of soil microbial communities between plantation forest of Pinus massoniana (PF) and naturally restored secondary forest (SF) in their organic horizon and mineral soil from a typical karst region in Southwest China. Our results showed that fungal communities differed more than bacterial communities between PF and SF, while the differences in archaeal communities were not significant. The most abundant fungal phylum in both mineral soil and organic horizon was Ascomycota at SF and Basidiomycota at PF, respectively. The PF soil had lower nitrogen (N) cycling gene abundance and lower inorganic N availability compared to SF soil probably because of the poor soil and lower litter quality. The SF soil had higher abundances of genes associated with labile carbon (C) (i.e., starch, hemicellulose, cellulose, pectin, and chitin) degradation compared with PF soil, but lower abundances of genes responsible for recalcitrant C (i.e., lignin and aromatics) degradation, which was strongly correlated with the litter properties. Simultaneous effects of soil and litter variables explained >50 % of the variation in microbial community structure and functional gene composition; soil nitrate-N had the strongest effect on the soil bacterial and fungal community structure. Our results highlight the superiority of naturally restored secondary forests for improving both soil fertility and soil microbial-mediated C and N cycling functions, which can support forest managers in selecting forest restoration approaches that optimize C and N storage in forest stands.

Desertification induced changes in soil bacterial and fungal diversity and community structure in a dry-hot valley forest

Increase in aridity is a global phenomenon due to climate change. Understanding soil microbial communities' response to aridity induced desertification is essential to predict the regulation of microbial processes under climate change and to develop feasible restoration plans. Therefore, to elucidate desertification effects, we investigated the changes in soil properties and, shifts and drivers of soil microbial diversity and community composition of a dry-hot valley-based Pinus densata forest located in south-east Tibetan Plateau of China. Amplicon sequencing of bacterial and fungal communities were used to determine soil bacterial and fungal community composition and diversity patterns. The results revealed that soil bacterial and fungal alpha-diversities were lower in desertified P. densata forest soils. Soil total carbon content (TC) was the major predictor of bacterial Pielou index. Whereas fungal Chao 1 and Simpson diversity indices were mainly influenced by total nitrogen contents (TN) of the soil. Differential response between soil bacterial and fungal communities' structures were observed between the desertified and non-desertified soils. Soil pH mainly regulated the overall microbial community structures in addition to TC determining bacterial and TN determining fungal community structures, respectively. Changes in the relative abundance of bacterial phylum Chloroflexi and Actinobacteria, and the ratio of fungal phylum Ascomycota/Basidiomycota were the indicators of intensity of soil desertification in the studied forests. The relative abundance of pathogenic microbial communities in soils was more in desertified soils in comparison to the non-desertified soils of P. densata forests, such as the bacterial genus Conexibacter and fungal genera Penicillium and Ilyonectria. This study evidences the differential response of soil bacterial and fungal communities to changes in soil biotic and abiotic properties indicating differential adaptive mechanism in a forest ecosystem currently experiencing adverse effects of rapid desertification.

Soil Fungal Community Characteristics at Timberlines of Sejila Mountain in Southeast Tibet, China.

Soil fungal community characteristics of alpine timberlines are unclear. In this study, soil fungal communities in five vegetation zones across timberlines on the south and north slopes of Sejila Mountain in Tibet, China were investigated. The results show that the alpha diversity of soil fungi was not different between the north- and south-facing timberlines or among the five vegetation zones. Archaeorhizomyces (Ascomycota) was a dominant genus at the south-facing timberline, whereas the ectomycorrhizal genus Russula (Basidiomycota) decreased with decreasing Abies georgei coverage and density at the north-facing timberline. Saprotrophic soil fungi were dominant, but their relative abundance changed little among the vegetation zones at the south timberline, whereas ectomycorrhizal fungi decreased with tree hosts at the north timberline. Soil fungal community characteristics were related to coverage and density, soil pH and ammonium nitrogen at the north timberline, whereas they had no associations with the vegetation and soil factors at the south timberline. In conclusion, timberline and A. georgei presence exerted apparent influences on the soil fungal community structure and function in this study. The findings may enhance our understanding of the distribution of soil fungal communities at the timberlines of Sejila Mountain.

Effects of Naphthalene Application on Soil Fungal Community Structure in a Poplar Plantation in Northern Jiangsu, China

The soil food web is essential for the functioning of terrestrial ecosystems. The application of naphthalene is a commonly employed experimental treatment for expelling soil fauna to examine faunal effects on litter decomposition processes, for which is it assumed that naphthalene has negligible effects on soil microbial communities. An experiment was conducted to examine the potential soil-fauna-repellent effect of naphthalene application (100 g/m2/month, TR) on a soil fungal community during litter decomposition. The results showed that TR greatly suppressed the abundance and taxonomic richness of soil fauna by 83.7 ± 14.2% and 48.1 ± 17.2%, respectively, and reduced the rates of poplar leaf litter decomposition compared to the control (CK, without naphthalene treatment). Among the fungal communities, the abundance of Thelephorales in the TR soil was suppressed, while the abundance of Capnodiales was stimulated, although TR did not significantly alter the carbon and nitrogen content in the soil microbial biomass nor the diversity of soil fungal communities and the most abundant fungal phylum. Thus, both the suppressed soil arthropod abundance and altered soil fungal community might contribute to the observed slowdown in litter decomposition. These results suggest that naphthalene, as a soil fauna repellent, can alter the abundance of specific taxa in a soil fungal community, thereby impeding the effort to elucidate the contribution of soil fauna to ecosystem functioning (e.g., with respect to litter decomposition).

Effects of mushroom-tobacco rotation on microbial community structure in continuous cropping tobacco soil.

Rotation is an effective strategy for controlling crop diseases and improving plant health. However, the effect of a mushroom-tobacco rotation on the composition and structure of microbial communities in continuous cropping soil is unclear. This study analysed the structure and function of soil bacterial and fungal communities using Illumina MiSeq high-throughput 16S rRNA gene sequencing. The results showed that the physicochemical properties (organic matter, available nitrogen, available phosphorus, and available potassium) and enzymatic activity (phosphatase, catalase, urease and invertase activity) in the rotation treatments (Y1, M1, Y2 and M2) were significantly higher than those in the control (continuous cropping) treatment (CK) and reached peak values in the M2 treatment. PCA showed that the soil microbial community structure in each rotation treatment was different from that in the control. The dominant bacterial phyla of the different soil treatments were Proteobacteria and Actinobacteriota, and the dominant fungal phyla of the different soil treatments were Ascomycota and Basidiomycota. The M2 rotation significantly reduced the relative abundance of harmful fungi (Penicillium and Gibberella) compared to the other treatments. RDA showed that the most abundant bacterial taxa were negatively correlated with pH and positively correlated with physicochemical properties. However, the most abundant fungal taxa were positively correlated with pH and negatively correlated with physicochemical properties. The mushroom-tobacco rotation can effectively maintain the ecological balance of the substrate microbial environment, and provide a more effective way to prevent the continuous cropping of tobacco.