Responses Of Soil Fungal Communities Research Articles

Responses of soil fungal community composition and function to wetland degradation in the Songnen Plain, northeastern China.

Wetlands are ecosystems that have a significant impact on ecological services and are essential for the environment. With the impacts of rapid population growth, wetland reclamation, urbanization, and land use change, wetlands have undergo severe degradation or loss. However, the response of soil fungal communities to wetland degradation remains unknown. It is crucial to comprehend how the diversity and population dynamics of soil fungi respond to varying levels of degradation and ecological progression in the wetlands of the Songnen Plain. In this study, high- throughput sequencing technology to analyze the variety and abundance of soil fungi in the undegraded (UD), light degraded (LD), moderate degraded (MD), and severe degraded (SD) conditions in the Halahai Nature Reserve of Songnen Plain. This study also explored how these fungi are related to the soil's physicochemical properties in wetlands at various degradation levels. The findings indicated that Basidiomycota and Ascomycota were the primary phyla in the Songnen Plain, with Ascomycota increasing and Basidiomycota decreasing as wetland degradation progressed. Significant differences were observed in soil organic carbon (SOC), total nitrogen (TN),and soil total potassium (TK) among the succession degradation stages. With the deterioration of the wetland, there was a pattern of the Shannon and Chao1 indices increasing and then decreasing. Non-metric Multidimensional Scaling (NMDS) analysis indicated that the fungal community structures of UD and LD were quite similar, whereas MD and SD exhibited more distinct differences in their fungal community compositions. Redundancy analysis (RDA) results indicated that Soil Water content (SWC) and total nitrogen (TN) were the primary environmental factors influencing the dominant fungal phylum. According to the FUNGuild prediction, Ectomycorrhizal and plant pathogens gradually declining with wetland degradation. In general, our findings can offer theoretical support develop effective solutions for the preservation and rehabilitation of damaged wetlands.

Response of soil fungal-community structure and function to land conversion to agriculture in desert grassland.

Land conversion to agriculture is an important factor affecting soil ecological processes in the desert grasslands of northern China. However, soil fungal-community structure and function in response to Land conversion remain unclear. In this study, desert grassland, artificial shrubland, and land conversion were investigated in the western part of the Mu Us Sandland (Yanchi, Ningxia; Dingbian, Shaanxi). We found that land conversion significantly increased soil total carbon, nitrogen, and phosphorus, and available phosphorous and potassium contents. In the early stage of conversion to agricultural (April), soil fungal operational taxonomic units and abundance-based coverage estimator were lower than those of dessert grasslands and shrubland plots and had significant correlations with pH, electric conductivity, and available phosphorus and potassium. The dominant phyla strongly correlated with soil physicochemical properties. Concomitantly, the relative abundance of Glomeromycota was significantly lower, and the complexity of the network in the land conversion plots was lower than that in the shrubland plots. In the late stage of land conversion (September), soil fungal operational taxonomic units and abundance-based coverage estimator were lower in the conversion plots than in the desert grassland plots, with more complex network relationships compared to the desert grassland or shrubland plots. Symbiotrophic groups, a functional group of desert grassland soil fungi, can be used as a predictor of environmental change; in addition, land conversion decreases the relative abundance of arbuscular mycorrhizal functional groups. Our study highlights the response of soil fungal communities and functions to human disturbances in desert grasslands. Considering the potential of land conversion to agriculture to influence soil secondary salinization, there is a need for continued observation of soil ecological health over the time continuum of land conversion to agriculture.

Response of Soil Fungal Community to Reforestation on Shifting Sand Dune in the Horqin Sandy Land, Northeast China.

Reforestation of native shrub on shifting sand dunes has been widely used for desertification control in semi-arid grassland in Northeast China. Previous studies have confirmed that plantation establishment facilitates fixing sand dunes, restoring vegetation, and improving soil properties, but very few have focused on the response of the soil fungal community. In this study, a chronosequence of Caragana microphylla (CM) shrub sand-fixation plantations (8-, 19-, and 33-year-old), non-vegetated shifting sand dunes (0 years), and adjacent natural CM forests (NCFs; 50-year-old) in the Horqin sandy land were selected as experimental sites. Soil properties including enzymatic activities were determined, and the composition and structure of the soil fungal community were investigated using the Illumina MiSeq sequencing technique based on the internal transcribed spacer (ITS) rDNA. This study aimed to (1) describe the response of the soil fungal community to revegetation onto a moving sand dune by planting a native shrub plantation; (2) determine the main soil factors driving the succession of the fungal community; and (3) discuss whether the soil fungal community can be restored to its original state by reforestation. The reforestation of CM significantly ameliorated soil properties, increased soil fungal diversity, and altered the composition and structure of the soil fungal community. Ascomycota, Basidiomycota, and Zoopagomycota were the dominant phyla in all sites. Ascomycota did not respond to plantation development, whereas the other two dominant phyla linearly increased or decreased with the plantation age. The relative abundance of dominant genera varied with sites and showed a waning and waxing characteristic. The composition and structure of the soil fungal community in the 33-year CM plantation were very close to that of the NCF, indicating the restorability of the soil fungal community. The succession of the soil fungal community was directly driven by soil properties, of which soil moisture, organic matter, total N, urease, and protease were the main affecting factors.

Response of soil fungal communities and their co-occurrence patterns to grazing exclusion in different grassland types.

Overgrazing and climate change are the main causes of grassland degradation, and grazing exclusion is one of the most common measures for restoring degraded grasslands worldwide. Soil fungi can respond rapidly to environmental stresses, but the response of different grassland types to grazing control has not been uniformly determined. Three grassland types (temperate desert, temperate steppe grassland, and mountain meadow) that were closed for grazing exclusion for 9 years were used to study the effects of grazing exclusion on soil nutrients as well as fungal community structure in the three grassland types. The results showed that (1) in the 0-5 cm soil layer, grazing exclusion significantly affected the soil water content of the three grassland types (P < 0.05), and the pH, total phosphorous (TP), and nitrogen-to-phosphorous ratio (N/P) changed significantly in all three grassland types (P < 0.05). Significant changes in soil nutrients in the 5-10 cm soil layer after grazing exclusion occurred in the mountain meadow grasslands (P < 0.05), but not in the temperate desert and temperate steppe grasslands. (2) For the different grassland types, Archaeorhizomycetes was most abundant in the montane meadows, and Dothideomycetes was most abundant in the temperate desert grasslands and was significantly more abundant than in the remaining two grassland types (P < 0.05). Grazing exclusion led to insignificant changes in the dominant soil fungal phyla and α diversity, but significant changes in the β diversity of soil fungi (P < 0.05). (3) Grazing exclusion areas have higher mean clustering coefficients and modularity classes than grazing areas. In particular, the highest modularity class is found in temperate steppe grassland grazing exclusion areas. (4) We also found that pH is the main driving factor affecting soil fungal community structure, that plant coverage is a key environmental factor affecting soil community composition, and that grazing exclusion indirectly affects soil fungal communities by affecting soil nutrients. The above results suggest that grazing exclusion may regulate microbial ecological processes by changing the soil fungal β diversity in the three grassland types. Grazing exclusion is not conducive to the recovery of soil nutrients in areas with mountain grassland but improves the stability of soil fungi in temperate steppe grassland. Therefore, the type of degraded grassland should be considered when formulating suitable restoration programmes when grazing exclusion measures are implemented. The results of this study provide new insights into the response of soil fungal communities to grazing exclusion, providing a theoretical basis for the management of degraded grassland restoration.

Response of Soil Fungal Community in Coastal Saline Soil to Short-Term Water Management Combined with Bio-Organic Fertilizer

This study aimed to elucidate the response of soil microbial communities to saline soil amelioration via biological organic fertilizer. A year-long experiment was conducted on coastal saline soil, employing water and fertilizer strategies. Three treatments were compared: dry field (control, CK), paddy field (W), and combined dry and irrigated fields with biological organic fertilizer (BW). Soil DNA was extracted and sequenced using high-throughput methods, revealing significant reductions in soil electrical conductivity (EC) and pH with W and BW treatments. Moreover, the BW treatment notably increased soil organic carbon content by 17.2%, as well as soil urease and alkaline phosphatase activity. Fungal community richness increased, with the BW treatment showing a 36% rise in the ACE index and a 24% increase in the Shannon index, while the Simpson index decreased by 59%. Dominant fungal phyla were Ascomycota, Mortierellomycota, and Basidiomycota, with Basidiomycota prevailing at the genus level. Redundancy analysis (RDA) indicated that soil pH, EC, and organic carbon were key determinants of fungal community distribution, with the BW treatment correlating negatively with pH and salt and positively with soil organic carbon (SOC). Fungal functional groups varied among treatments, with saprophytic fungi predominating, but the BW treatment showed a higher relative abundance of animal pathogenic fungi. In summary, the integration of biological organic fertilizer with flooding ameliorates soil properties and influences the changes in soil fungal community structure and function in the short term. These results could enhance the scientific basis for the efficient utilization and development of saline soil resources in coastal areas.

Drought mediates the response of soil fungal communities post-wildfire in a Californian grassland and coastal sage scrubland

There is a knowledge gap surrounding how drought and wildfire, two increasingly frequent disturbances, will alter soil fungal communities. Moreover, studies that directly compare ambient and drought-treated soil fungal communities in the context of wildfire are exceptionally scarce. We assessed the response and recovery of soil fungal communities and functional guilds in two sites – a grassland and a coastal sage shrubland – after a severe wildfire burned a long-term drought experiment. We collected soil samples at four collection dates over an eight-month period after wildfire and amplified fungal DNA. We predicted that fungal communities within the drought and ambient treatments would differ significantly across collection dates owing to differing responses to post-wildfire conditions. Richness was stable across collection dates, regardless of precipitation treatment, in both sites. Differences between treatments were significant at every collection date with respect to taxonomical community composition. Differences in community composition between collection dates within each treatment were also significant. Additionally, the monotonic trends of drought and ambient communities over time differed in strength and direction. Differences in shrubland functional guild composition across collection dates and contrasting trends suggest a drought-dependent shift after the fire. Overall, we conclude that drought mediates how soil fungal communities respond after a wildfire in the long term, however drought effects may differ across ecosystems.

Response of Soil Fungal Community to Biochar Application Under Different Irrigation Water Salinity

Saline water irrigation can alleviate the shortage of freshwater resources in the northwest arid zone, but long-term saline water irrigation can damage the soil fungal community structure. To alleviate the harm caused by salinity, biochar is used as a soil amendment to improve the soil fungal community structure. To investigate the intrinsic link between biochar application and the structural diversity of fungal communities in saline soils, two irrigation water salinity levels were set:0.35 dS·m-1 (fresh water) and 8.04 dS·m-1 (saline water). At each irrigation water salinity, two levels of biochar application were set:0 t·hm-2 (no application) and 3.7 t·hm-2 (application). High-throughput sequencing results showed that compared to that under fresh water irrigation, saline water irrigation increased fungal community species diversity and decreased fungal community species richness; biochar application under saline water irrigation reduced soil fungal community species diversity and species richness. The dominant fungal phyla in the soils of each treatment were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Rozellomycota, and Cysticercales, and the dominant genera were Gibberella, Chaetomium, Sarocladium, Stachybotrys, and Fusarium. Compared to that under freshwater irrigation, saline water irrigation significantly increased the relative abundance of Basidiomycota and Chytridiomycota and significantly decreased the relative abundance of Ascomycota and Rozellomycota. The application of biochar under saline irrigation significantly increased the relative abundance of Ascomycota and Sarocladium but significantly decreased the relative abundance of Basidiomycota, Chaetomium, and Fusarium. LEfSe analysis showed that under the condition of no biochar application, saline irrigation reduced the number of potential biomarkers of fungal communities, whereas the application of biochar under the condition of saline irrigation increased the number of potential biomarkers of fungal communities. These results indicated that the application of biochar can improve the saline soil environment and fungal community structure and provide a theoretical basis for reasonable brackish water irrigation and soil fertilization in arid areas.

Changes in nitrogen and phosphorus availability driven by secondary succession in temperate forests shape soil fungal communities and function.

The soil fungal community plays an important role in forest ecosystems and is crucially influenced by forest secondary succession. However, the driving factors of fungal community and function during temperate forest succession and their potential impact on succession processes remain poorly understood. In this study, we investigated the dynamics of the soil fungal community in three temperate forest secondary successional stages (shrublands, coniferous forests, and deciduous broad-leaved forests) using high-throughput DNA sequencing coupled with functional prediction via the FUNGuild database. We found that fungal community richness, α-diversity, and evenness decreased significantly during the succession process. Soil available phosphorus and nitrate nitrogen decreased significantly after initial succession occurred, and redundancy analysis showed that both were significant predictors of soil fungal community structure. Among functional groups, fungal saprotrophs and pathotrophs represented by plant pathogens were significantly enriched in the early-successional stage, while fungal symbiotrophs represented by ectomycorrhiza were significantly increased in the late-successional stage. The abundance of both saprotroph and pathotroph fungal guilds was positively correlated with soil nitrate nitrogen and available phosphorus content. Ectomycorrhizal fungi were negatively correlated with nitrate nitrogen and available phosphorus content and positively correlated with ammonium nitrogen content. These results indicate that the dynamics of fungal community and function reflected the changes in nitrogen and phosphorus availability caused by the secondary succession in temperate forests. The fungal plant pathogen accumulated in the early-successional stage and ectomycorrhizal fungi accumulated in the late-successional stage may have a potential role in promoting forest succession. These findings contribute to a better understanding of the response of soil fungal communities to secondary forest succession and highlight the importance of fungal communities during the successional process.

Temporal dynamics of soil fungi in a pyrodiverse dry-sclerophyll forest.

Fire is a major evolutionary and ecological driver that shapes biodiversity in forests. While above-ground community responses to fire have been well-documented, those below-ground are much less understood. However, below-ground communities, including fungi, play key roles in forests and facilitate the recovery of other organisms after fire. Here, we used internal transcribed spacer (ITS) meta-barcoding data from forests with three different times since fire [short (3 years), medium (13-19 years) and long (>26 years)] to characterize the temporal responses of soil fungal communities across functional groups, ectomycorrhizal exploration strategies and inter-guild associations. Our findings indicate that fire effects on fungal communities are strongest in the short to medium term, with clear distinctions between communities in forests with a short time (3 years) since fire, a medium time (13-19 years) and a long time (>26 years) since fire. Ectomycorrhizal fungi were disproportionately impacted by fire relative to saprotrophs, but the direction of the response varied depending on morphological structures and exploration strategies. For instance, short-distance ectomycorrhizal fungi increased with recent fire, while medium-distance (fringe) ectomycorrhizal fungi decreased. Further, we detected strong, negative inter-guild associations between ectomycorrhizal and saprotrophic fungi but only at medium and long times since fire. Given the functional significance of fungi, the temporal changes in fungal composition, inter-guild associations and functional groups after fire demonstrated in our study may have functional implications that require adaptive management to curtail.

A Natural Moisture Gradient Affects Soil Fungal Communities on the South Shore of Hulun Lake, Inner Mongolia, China.

Soil moisture content (SWC) can change the diversity and composition of soil fungal communities by affecting soil texture and soil nutrients. To explore the response of soil fungal communities to moisture in the grassland ecosystem on the south shore of Hulun Lake, we set up a natural moisture gradient that was subdivided into high (HW), medium (MW), and low (LW) water contents. Vegetation was investigated by quadrat method, and aboveground biomass was collected by the mowing method. Soil physicochemical properties were obtained by internal experiments. The composition of the soil fungal community was determined using high-throughput sequencing technology. The results showed significant differences in soil texture, nutrients, and fungal species diversity under the moisture gradients. Although there was significant clustering of fungal communities in different treatments, the fungal community composition was not significantly different. According to the phylogenetic tree, the Ascomycota and Basidiomycota were the most important branches. The fungal species diversity was smaller when SWC was higher, and in this environment (HW), the fungal-dominant species were significantly related to SWC and soil nutrients. At this time, soil clay formed a protective barrier for the survival of the dominant classes Sordariomycetes and Dothideomycetes and increased their relative abundance. In summary, the fungal community responded significantly to SWC on the southern shore of the Hulun Lake ecosystem in Inner Mongolia, China, and the fungal community composition of the HW group was stable and easier to survive.

Niche modelling predicts that soil fungi occupy a precarious climate in boreal forests

AbstractAimEfforts to predict the responses of soil fungal communities to climate change are hindered by limited information on how fungal niches are distributed across environmental hyperspace. We predict the climate sensitivity of North American soil fungal assemblage composition by modelling the ecological niches of several thousand fungal species.LocationOne hundred and thirteen sites in the United States and Canada spanning all biomes except tropical rain forest.Major Taxa StudiedFungi.Time Period2011–2018.MethodsWe combine internal transcribed spacer (ITS) sequences from two continental‐scale sampling networks in North America and cluster them into operational taxonomic units (OTUs) at 97% similarity. Using climate and soil data, we fit ecological niche models (ENMs) based on logistic ridge regression for all OTUs present in at least 10 sites (n = 8597). To describe the compositional turnover of soil fungal assemblages over climatic gradients, we introduce a novel niche‐based metric of climate sensitivity, the Sørensen climate sensitivity index. Finally, we map climate sensitivity across North America.ResultsENMs have a mean out‐of‐sample predictive accuracy of 73.8%, with temperature variables being strong predictors of fungal distributions. Soil fungal climate niches clump together across environmental space, which suggests common physiological limits and predicts abrupt changes in composition with respect to changes in climate. Soil fungi in North American climates are more likely to be limited by cold and dry conditions than by warm and wet conditions, and ectomycorrhizal fungi generally tolerate colder temperatures than saprotrophic fungi. Sørensen climate sensitivity exhibits a multimodal distribution across environmental space, with a peak in climates corresponding to boreal forests.Main ConclusionsThe boreal forest occupies an especially precarious region of environmental space for the composition of soil fungal assemblages in North America, as even small degrees of warming could trigger large compositional changes characterized mainly by an influx of warm‐adapted species.

Response of soil fungal community to chromium contamination in agricultural soils with different physicochemical properties

Chromium (Cr) contamination has been of great concern in agricultural soil health due to its persistence, toxicity and bioaccumulation. Fungi, as an essential regulator of soil remediation and biochemical processes, had an unclear response to Cr contamination. In this study, the composition, diversity and interaction mechanisms of fungal communities in agricultural soils from ten different provinces of China were investigated in order to elucidate the fungal community response to varying soil properties and Cr concentrations. The results showed that high concentrations of Cr led to substantial alterations in the fungal community composition. The complex soil properties had a far greater impact on the fungal community structure than the single factor of Cr concentration, with soil available phosphorus (AP) and pH being most influential. Function predictions based on FUNGuild indicated that high concentrations of Cr have a significant impact on certain functional groups of fungi, including mycorrhizal fungi and plant saprotroph. The fungal community tended to resist Cr stress by enhancing interactions and clustering among network modules, while generating new keystone taxa. This study allowed insights into the response of soil fungal community to Cr contamination in different agricultural soils from different provinces and provided a theoretical basis for soil Cr ecological risk assessment and the development of bioremediation techniques for Cr-contaminated soils.

Responses of soil fungal communities and functional guilds to ~160 years of natural revegetation in the Loess Plateau of China.

Natural revegetation has been widely confirmed to be an effective strategy for the restoration of degraded lands, particularly in terms of rehabilitating ecosystem productivity and soil nutrients. Yet the mechanisms of how natural revegetation influences the variabilities and drivers of soil residing fungal communities, and its downstream effects on ecosystem nutrient cycling are not well understood. For this study, we investigated changes in soil fungal communities along with ~160 years of natural revegetation in the Loess Plateau of China, employing Illumina MiSeq DNA sequencing analyses. Our results revealed that the soil fungal abundance was greatly enhanced during the later stages of revegetation. As revegetation progresses, soil fungal richness appeared first to rise and then decline at the climax Quercus liaotungensis forest stage. The fungal Shannon and Simpson diversity indexes were the lowest and highest at the climax forest stage among revegetation stages, respectively. Principal component analysis, Bray–Curtis similarity indices, and FUNGuild function prediction suggested that the composition, trophic modes, and functional groups for soil fungal communities gradually shifted along with natural revegetation. Specifically, the relative abundances of Basidiomycota, Agaricomycetes, Eurotiomycetes, and ectomycorrhizal fungi progressively increased, while that of Ascomycota, Sordariomycetes, Dothideomycetes, Tremellomycetes, saprotrophic, pathotrophic, arbuscular mycorrhizal fungi, and endophyte fungi gradually decreased along with natural revegetation, respectively. The most enriched members of Basidiomycota (e.g., Agaricomycetes, Agaricales, Cortinariaceae, Cortinarius, Sebacinales, Sebacinaceae, Tricholomataceae, Tricholoma, Russulales, and Russulaceae) were found at the climax forest stage. As important carbon (C) sources, the most enriched symbiotic fungi (particularly ectomycorrhizal fungi containing more recalcitrant compounds) can promote organic C and nitrogen (N) accumulation in soils of climax forest. However, the most abundant of saprotrophic fungi in the early stages of revegetation decreased soil organic C and N accumulation by expediting the decomposition of soil organic matter. Our results suggest that natural revegetation can effectively restore soil fungal abundance, and modify soil fungal diversity, community composition, trophic modes, and functional groups by altering plant properties (e.g., plant species richness, diversity, evenness, litter quantity and quality), quantity and quality of soil nutrient substrates, soil moisture and pH. These changes in soil fungal communities, particularly their trophic modes and functional groups along with natural revegetation, impact the accumulation and decomposition of soil C and N and potentially affect ecosystem C and N cycling in the Loess Plateau of China.

Difference responses of soil fungal communities to cattle and chicken manure composting application.

Cattle and poultry manure composting are often applied on agricultural lands but the fungal community composition before and after application in soils is still unclear. This study describes soil fungal diversity after manure applications contribute to the correct resource use of livestock and poultry manures. Fresh manure samples were obtained from 10 beef cow farms and 12 egg-laying poultry farms at five distinct phases of rearing. Surface soil samples were collected from vegetable plots within the farms after manure application at 15, 30 and 45 t hm-2 . Using high-throughput sequencing techniques, the ITS region was used to describe soil fungus populations. The fungal OTUs, Chao1 and ACE of cattle manure were relatively higher in the fattening stage (>12months), the OTUs and ACE of chicken manure were the highest in the initial laying stage (16-24 weeks). The fungal diversity indices of vegetable soils had no linear change after cow or chicken manure application compared with the control. Ascomycota (84.7% of total sequences), Neocallimastigomycota (9.69%) and Basidiomycota (4.6%) were the dominant phyla in cattle manure. Ascomycota (88.9%) also predominated in chicken manure followed by Basidiomycota (8.9%). Following both cattle and chicken manure applications, the abundance of Ascomycota decreased, whereas Basidiomycota and Chytridiomycota increased in the soils. None of the dominant genus increased or decreased linearly with the increase of cattle and chicken composting application rate. The fungal-dominant genera of the soils with and without manure composting application were mostly affected by soil pH and EC than manure. Pearson's correlation analysis revealed that organic matter, Cu and Hg contents were strongly linked to the fungal diversity and the abundance of specific taxa in cattle manure. In chicken manure, OM, TN and Zn were major factors controlling the fungal diversity and community composition. Soil pH, EC and Cu, Zn, Cd, Hg and As content had pronounced effects on the beneficial and pathogenic genus in soil with and without manure composting. Beneficial fungal genus such as Aspergillus, Plectosphaerella, Acremonium, Meyerozyma and fungal pathogenic such as Fusarium, Cladosporium, Verticillium were sensitive to properties (EC, pH, OM) and heavy metals (Cu, Zn, Hg) contents of the environment relatively. This study can serve as an applicable contribution helping in farms management (especially to cattle and poultry breeding) and improving their resource use of livestock and poultry manures. Soil heterogeneity rather than manure determines fungal communities in the vegetable fields, but we can encourage the sensible use of cattle and chicken manures in agroecosystems. This study will help farmers regulate the dosage of feed components which can increase the number of beneficial fungal genus or reduce the number of pathogenic fungal genus, improve their resource use of livestock and poultry manures and encourage the sensible use of cattle and chicken manures in agroecosystems.

Changes in litter input exert divergent effects on the soil microbial community and function in stands of different densities

Soil microbial communities influence soil biogeochemical cycling by affecting the production of extracellular enzymes and the release of carbon dioxide. Changes in litter input or stand density due to thinning can affect soil microbial communities and their function by altering soil biochemical properties. However, it is unclear how or to what extent different amounts of litter input affect soil microbial communities and their function in forest stands with different densities. Therefore, we simulated litter removal, 50 % litter reduction, normal litter input, and double litter increase under field conditions by applying different amounts of litter to soils with different stand densities in the laboratory. We then measured soil biochemical properties, microbial communities, enzyme activity, and respiration rate.Our results revealed that the responses of soil dissolved organic carbon and total nitrogen to litter input were more pronounced in the high-density forest stand with poor soil than in the low-density forest stand with nutrient-rich soil, which was mainly reflected in that the addition of litter significantly decreased the concentration of dissolved organic carbon while increasing the content of total nitrogen in the soil of the high-density forest stand. In comparison to the soil carbon component, the nitrogen component of the soil was more affected by stand density. The responses of soil fungal and bacterial communities to leaf litter treatment varied with stand density, as reflected primarily in changes in the relative abundances of Ascomycota, unclassified_K_fungi, and Proteobacteria, and changes in the relative abundances of their functional groups (ectomycorrhizal fungi, saprophytic fungi, pathogens, parasites, and bacteria involved in the nitrogen cycle). Soil fungal community responses to changes in litter input are more sensitive in the high-density forest with nutrient-poor soil than in the low-density forest stand. Furthermore, litter input inhibited the activities of soil β-glucuronidase, N-acetyl-β-d-glucosaminidase, and acid phosphatase more strongly in the low-density forest stand. Litter manipulation primarily affected enzymatic activity in the high-density forest stand by changing the diversity and composition of the soil fungal community. However, in the low-density forest stand, litter treatment affected soil enzyme activity, primarily through changes in soil bacterial and fungal community composition, as well as soil respiration through changes in bacterial richness (Chao 1) and community composition.We conclude that how the change in litter input impacts the soil microbial community and its function, or the magnitude of the effects, is largely dependent on soil quality. Relationships among soil variables, microbial communities, and function differ between stand densities. Our study contributes to an enhanced understanding of the impact of changes in litter input due to climate change or anthropogenic activities on soil biogeochemical cycles and can also guide rationally formulating forest management approaches to improve microbial function under climate change.

Combined Application of Manure and Chemical Fertilizers Alters Soil Environmental Variables and Improves Soil Fungal Community Composition and Rice Grain Yield.

Soil microorganisms play vital roles in energy flow and soil nutrient cycling and, thus, are important for crop production. A detailed understanding of the complex responses of microbial communities to diverse organic manure and chemical fertilizers (CFs) is crucial for agroecosystem sustainability. However, little is known about the response of soil fungal communities and soil nutrients to manure and CFs, especially under double-rice cropping systems. In this study, we investigated the effects of the application of combined manure and CFs to various fertilization strategies, such as no N fertilizer (Neg-CF); 100% chemical fertilizer (Pos-CF); 60% cattle manure (CM) + 40% CF (high-CM); 30% CM + 70% CF (low-CM); 60% poultry manure (PM) + 40% CF (high-PM), and 30% PM + 70% CF (low-PM) on soil fungal communities' structure and diversity, soil environmental variables, and rice yield. Results showed that synthetic fertilizer plus manure addition significantly increased the soil fertility and rice grain yield compared to sole CFs' application. Moreover, the addition of manure significantly changed the soil fungal community structure and increased the relative abundance of fungi such as phyla Ascomycota, Basidiomycota, Mortierellomycota, and Rozellomycota. The relative abundances dramatically differed at each taxonomic level, especially between manured and non-manured regimes. Principal coordinates analysis (PCoA) exhibited greater impacts of the addition of manure amendments than CFs on fungal community distributions. Redundancy analysis showed that the dominant fungal phyla were positively correlated with soil pH, soil organic C (SOC), total N, and microbial biomass C, and the fungal community structure was strongly affected by SOC. Network analysis explored positive relationships between microorganisms and could increase their adaptability in relevant environments. In addition, the structural equation model (SEM) shows the relationship between microbial biomass, soil nutrients, and rice grain yield. The SEM showed that soil nutrient contents and their availability directly affect rice grain yield, while soil fungi indirectly affect grain yield through microbial biomass production and nutrient levels. Our results suggest that manure application combined with CFs altered soil biochemical traits and soil fungal community structure and counteracted some of the adverse effects of the synthetic fertilizer. Overall, the findings of this research suggest that the integrated application of CF and manure is a better approach for improving soil health and rice yield.

Response of Soil Fungal Communities in Diversified Rotations of Wheat and Different Crops

Crop-soil microorganism interactions and feedback are critical to soil health and crop production. The aim of this study was to clarify the difference in soil fungal communities under diversified rotations of wheat and different crops in the North China Plain and to provide a theoretical basis for the construction and optimization of ecological sustainable planting systems. The soil fungal community abundance, composition, and diversity of continuous winter wheat-summer maize M, winter wheat-summer peanut (summer maize) PM, and winter wheat-summer soybean (summer maize) SM treatments were studied using real-time quantitative PCR and high-throughput sequencing technology. The results showed that, compared with those of the continuous winter wheat-summer maize treatment, the peanut rotation treatment PM2 and soybean rotation treatment SM2 significantly reduced soil fungal ITS sequence copy numbers (P<0.05); there was no significant difference in soil fungal ITS sequence copy numbers between other rotation treatments and those of the control (P>0.05). Rotation treatments with peanut or soybean increased soil fungal community richness (Chao1 and ACE indices) and diversity (Shannon and InvSimson indices), in which the community richness of all rotation treatments and the community diversity of SM1/SM2 treatments varied significantly (P<0.05). The result of non-metric multidimensional scaling (NMDS) analysis showed that the soil fungal community among different rotation crops were obviously separated. The rotation crops significantly affected soil fungal community structure (PERMANOVA:r2=0.350, P=0.001; ANOSIM:r=0.478, P=0.001). Ascomycota (73.67%-85.48%) was the dominant phylum, whereas Sordariomycetes (30.53%-48.19%) and Eurotiomycetes (11.12%-31.19%) were the dominant classes of the fungal communities of sandy-loam fluvo-aquic soil in the North China Plain. There were significantly different taxa of soil fungal communities in different rotations. Potential pathogens such as Neocosmospora, Plectosphaerella, and Gibellulopsis were significantly enriched in the rotations of winter wheat-summer peanut (summer maize), whereas potential beneficial fungi such as Penicillium and Zopfiella were significantly enriched in the rotations of winter wheat-summer soybean (summer maize). Compared with that under the continuous winter wheat-summer maize treatment, rotations with peanut or soybean increased the relative abundance of pathotroph, pathotroph-symbiotroph, and saprotroph-symbiotroph fungi and decreased the relative abundance of saprotroph fungi. The soil fungal community richness and structure were significantly related to soil organic carbon and available nutrients, and the Shannon diversity index was significantly related to soil mineral nitrogen and available phosphorus. In summary, on the basis of continuous winter wheat-summer maize rotation in the North China Plain, adding summer peanut or summer soybean instead of summer maize for rotations with different interval years could increase the richness and diversity of soil fungal communities and significantly change soil fungal community structure. In particular, summer soybean as the preceding crop had a positive effect on the enrichment of potential beneficial fungi.

Responses of Soil Fungal Communities to Subalpine Meadow Degradation in Mount Wutai

Grassland degradation has become a worldwide ecological problem. Although soil microorganisms, as the main participants in the process of grassland degradation, play a key role in maintaining ecosystem function and improving soil productivity, little is known about the changes in microbial communities caused by grassland degradation and their relationship with soil properties and plant communities. In this study, we used Illumina MiSeq sequencing to analyze the soil fungal communities of subalpine meadow soil at four different degradation stages[i.e., non-degraded (ND), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD)] on Mount Wutai. The results showed that Ascomycota, Basidiomycota, and Zygomycota were the dominant phyla of soil fungi in the subalpine meadow, regardless of degradation stage. LEfSe showed that the subalpine meadows with different degradation degrees were enriched with different biomarkers. Compared with ND, MD and HD were enriched with more pathogenic fungi. Moreover, HD apparently decreased the richness and Shannon indexes of soil fungal communities compared with those of ND. Non-metric multidimensional scaling (NMDS) and similarity analysis (ANOSIM) indicated that the compositions and structures of fungal communities were significantly different among meadows with different degradation degrees (P<0.05). Redundancy analysis (RDA) showed that soil water content, total nitrogen, plant richness, and ammonium nitrogen were significantly correlated with the compositions and structures of fungal communities (P<0.05). There were significant correlations between α diversity and β diversity between plant and fungal communities (P<0.05), indicating strong coupling. The results of our study provide a theoretical basis for further research on the changes in soil fungal communities and their driving mechanism in different degradation stages of subalpine meadows.

The negative effect of Chinese fir (Cunninghamia lanceolata) monoculture plantations on soil physicochemical properties, microbial biomass, fungal communities, and enzymatic activities

Considerable natural or secondary forests have been converted to plantations in response to the growing needs for timber, paper, and fuel. Soil fungal communities are sensitive to ecosystem transformation and play an important role in aboveground-belowground linkages and biogeochemical cycling. However, the effect of forest conversion on fungal community structure and functions and driving mechanisms remains unclear. We investigated the response of soil fungal communities and the corresponding change in soil physicochemical biological properties and enzymatic activities to the natural broad-leaved forest (NBF) converted to the Chinese fir (Cunninghamia lanceolata) plantation (CFP) in subtropical China with ITS rRNA amplicon sequencing. Soil physicochemical properties, microbial biomass, fungal alpha diversities, and enzymatic activities decreased with forest conversion, including pH, soil water content, soil organic carbon, available phosphorus, total nitrogen, nitrate nitrogen, microbial biomass carbon and nitrogen, urease, protease, and acid phosphatase. Fungal community composition and structure were also strongly affected by forest conversion. Ascomycota had a higher read abundance in the NBF, but Basidiomycota showed a higher read abundance in the CFP. The read abundance of saprotroph and arbuscular mycorrhizal fungi increased with forest conversion, while that of ectomycorrhizal fungi decreased. Some fungal guilds—dung saprotrophs, lichenized fungi, endophytes, and lichen parasites—were even nearly lost in the CFP. These changes in fungal communities are all closely correlated to soil physicochemical properties, microbial biomass, and enzymatic activities. Overall, our study emphasizes the negative effect of the NBF conversion to the CFP on C, N, and P cycling mediated by fungi—and recommends replacing monoculture coniferous forests with mixed forests in reforestation to improve soil degradation.

Influence of tea-Pleurotus ostreatus intercropping on soil fungal diversity and community structure

Understanding the relationship between soil fungal communities and soil function is vital to establish a sustainable and ecologically friendly tea (Camellia sinensis L.) cultivation. However, there is limited research on the response of soil fungal communities to tea-fungus intercropping, particularly how it is related to soil biodiversity and fertility. Here, we assessed and compared the fungal communities using a metabarcoding technique, soil properties in three plantations (1, 2, and 5 yr of tea-Pleurotus intercropping plantations), and a 5 yr chemically fertilized monoculture plantation. We obtained a total of 3493 operational taxonomic units (OTUs) from four tea plantations. Five hundred and ninety-three fungal OTUs are shared by all plantations, and the other 471 fungal OTUs are shared by three plantations. The largest number of OTUs was recorded in 5 yr tea-Pleurotus intercropped plantations (N = 2040), followed by 2 yr (N = 2024) and then 1 yr (N = 1471), while the chemically fertilized plantation recorded 1823 OTUs. Tea-Pleurotus intercropping showed a significant effect on the increased diversity of soil fungal diversity compared with the monoculture tea cultivations. Fungal groups Basidiomycota, Ascomycota, and Mortierellomycota were the most abundant taxonomic groups recorded in all soil samples. Principal coordinate analysis revealed that fungal community composition in tea-Pleurotus intercropped plantations and monoculture tea plantations was significantly different. Besides, redundancy analysis revealed that soil nutrients significantly influence soil fungal community composition. Our results demonstrate that tea-Pleurotus intercropping may offer long-term benefits to soil biodiversity and sustainable benefits in the tea plantations.