Soil Fungal Community Structure Research Articles

Comparative Analysis of Fungal Diversity and Community Structure of Different Volcanic Soils in Wudalianchi, China

The relationship between the fungal community characteristics and soil environmental factors of volcanic ecosystem in Wudalianchi, China were investigated. The soil fungal community structure and diversity of new, old, and non-erupting volcanos were explored through highthroughput sequencing technology. The result showed that the physical and chemical properties of three plots were significantly different. Through sequencing 578 species, 366 genera, 202 families, 89 orders, 32 classes, and 11 phyla were detected. Among them Ascomycota and Basidiomycota were the dominant fungi phyla. The relative abundance of various flora determined by phylum classification showed significant differences. The Shannon, Simpson, Ace, and Chao1 indices for the soil fungi in the three plots were also significantly different. Redundancy and correlation analyses showed that the α diversity of fungi was significantly correlated with pH, organic matter and total nitrogen in the soil. These results indicate that soil environmental factors influence the fungal diversity in the different volcanic ecosystems in Wudalianchi, China.
 Bangladesh J. Bot. 50(2): 327-334, 2021 (June)

Soil degradation influences soil bacterial and fungal community diversity in overgrazed alpine meadows of the Qinghai-Tibet Plateau

Over half of the alpine meadows in the Qinghai-Tibet Plateau (QTP) are degraded due to human activities. Soil degradation from overgrazing is the most direct cause of grassland degradation. It is thus important to synthesize the effects of multiple soil degradation indicators on the belowground biomass of plants and soil microorganisms in the degraded QTP. We studied the diversities and structures of soil bacterial and fungal communities using soil bacterial 16S rRNA and the fungal ITS gene under four degradation gradients, D1: lightly degraded, D2: moderately degraded, D3: highly degraded, and a non-degraded control site (CK). The bacterial Shannon diversity in D3 was significantly lower than that in D1 (p < 0.001), and the bacterial richness index in D3 was significantly lower than that in D1 (p < 0.001). There was no difference in soil fungal diversity among the different degradation levels; however, soil fungal richness decreased significantly from CK to D3. The phyla Actinobacteria, Acidobacteria and the genus Mortierella were differed significantly under the four degradation gradients. Plant litter mass and root C/N ratio were important factors associated with bacterial and fungal diversity and richness. These results indicated that alpine meadow degradation can lead to variations in both microbial diversity and the potential functioning of micro-organisms in the QTP.

Changes of soil bacterial and fungal community structure along a natural aridity gradient in desert grassland ecosystems, Inner Mongolia

Environmental aridity is increasing in several regions around the globe due to climate change. However, little is known about microbial diversity and community responses to aridity along grassland-to-desert gradients. We investigated soil bacterial and fungal diversity and composition, and associated environmental factors along an aridity gradient across grassland (G), desert-grassland (DG) and desert (D) in Inner Mongolia, Northern China. The results indicate that soil microbial diversity decreased significantly from G and DG to D. Bacteria were mostly dominated by the universal phyla Proteobacteria, Actinobacteria, Bacteroidetes and Acidobacteria. Fungal communities were dominated only by Ascomycota. Most bacterial species (58.7–69.1%) were found in all habitats with significant differences among the three vegetation types, while most soil fungal species occupied small geographic areas. Soil bacterial communities adapted to environmental changes through changes in proportions of their taxa, while fungi changed their rare taxa in response to the differences in local environments. Canonical correspondence analysis (CCA) indicated that soil C:N, salinity and regional temperature were the most important factors regulating microbial community composition. Structural equation models (SEM) revealed that C:N was the most important factor directly influencing soil microbial diversity, and SPEI was the most important factor indirectly influencing soil microbial diversity in the Mongolian desert-grassland ecosystem. Our results provide evidence that soil bacterial and fungal communities respond differently to the changes in the biotic and abiotic factors, reflecting different adaptive strategies for coping with climate change in desert grassland ecosystems.

Soil Fungal Community Structure in Boreal Pine Forests: From Southern to Subarctic Areas of Finland.

The boreal forest environment plays an important role in the global C cycle due to its high carbon storage capacity. However, relatively little is known about the forest fungal community at a regional scale in boreal forests. In the present study, we have re-analyzed the data from our previous studies and highlighted the core fungal community composition and potential functional groups in three forests dominated by Scots pine (Pinus sylvestris L.) in Finland, and identified the fungal generalists that appear across geographic locations despite differences in local conditions. The three forests represent subarctic, northern and southern boreal forest, and are all in an un-managed state without human interference or management. The subarctic and northern areas are subject to reindeer grazing. The results showed that the three locations formed distinct fungal community structures (P < 0.05). Compared to the two northern locations, the southern boreal forest harbored a greater abundance of Zygomycota, Lactarius, Mortierella Umbelopsis, and Tylospora, in which aspect there were no differences between the two northern forests. Cortinarius, Piloderma, and Suillus were the core fungal genera in the boreal Scots pine forest. Functionally, the southern boreal forest harbored a greater abundance of saprotroph, endophytes and fungal parasite-lichen, whereas a greater abundance of ectomycorrhizal fungi was observed in the northern boreal forests. Moreover, the pathotroph and wood saprotrophs were commonly present in these three regions. The three locations formed two distinct fungal community functional structures, by which the southern forest was clearly separated from the two northern forests, suggesting a distance–decay relationship via geographic location. This study provides useful information for better understanding the common fungal communities and functions in boreal forests in different geographical locations.

Effects of long-term integrated agri-aquaculture on the soil fungal community structure and function in vegetable fields

The diversity and community structure of soil fungi play an important role in crop production and ecosystem balance, especially in paddy-upland vegetable field systems. High-throughput sequencing was used to study changes in the soil fungal community structure and function in paddy-upland vegetable field systems. The results showed that compared with traditional planting, the diversity and community structure of soil fungi were changed by the combination of flooding and drought, the Shannon index increased by 11.07%, and the proportion of the dominant species, Mortierella, decreased by 22.74%. Soil available nitrogen, total phosphorus, available phosphorus, total nitrogen and organic matter played a leading role in the initial stage of the experiment, while the dominant factor changed to total potassium 3 years later and then to soil pH and water content 6 years later. FUNGuild analysis showed that the proportion of three independent trophic modes of soil fungi were increased by the combined flooded-drought model, and there were multiple interaction factors, For example, nutrient supply, pH and planting pattern. This study showed that soil fertility, crop yield and economic benefits were better than the traditional model after three years of planting and breeding. The longer the time, the better the effect.

Different Urban Forest Tree Species Affect the Assembly of the Soil Bacterial and Fungal Community.

The selection of tree species used for the afforestation of urban forests is very important for maintaining the urban ecosystem, while soil microbe is one of the driving factors of material cycling in the urban forest ecosystem and for health of forests. In this study, the characteristics of surface soil bacterial and fungal community structure in four urban forests (primarily composed of Fraxinus mandshurica (Fm), Quercus mongolica (Qm), Pinus sylvestris var. mongolica (Ps), and Pinus tabulaeformis var. Mukdensis (Pt) as the main dominant tree species, respectively) were investigated by high-throughput sequencing. Our results showed that the alphadiversity of the soil microbial community in the Fm urban forest was the highest, while the lowest was in the Ps urban forest. In the bacterial community, Proteobacteria was the most predominant phylum in soils from Fm, Ps, and Pt urban forests. The most relatively abundant phylum of the Qm urban forest soil was Acidobacteria. The relative abundances of the bacterial communities at the genus level in the soil of four urban forests were significantly different. The soil bacterial communities in Ps and Pt urban forests were moresimilar, and Qm and Fm were also moresimilar. In the fungal community, Basidiomycota was the most predominant phylum in soils from Qm, Ps, and Pt urban forests. The phylum with the greatest relative abundance in the Fm urban forest soil was Ascomycota. There were differences in the fungal community between Qm, Fm, Ps, and Pt urban forests. Soil microbial community composition was affected by environmental factors: soil bacterial and fungal community compositions were significantly related to soil electrical conductivity (EC), alkali hydrolysable nitrogen (AHN), total nitrogen (TN), and total phosphorus (TP).In conclusion, the soil microbial community structure was related to both forest's tree species and soil properties.

Responses of Soil Fungal Communities to Lime Application in Wheat Fields in the Pacific Northwest.

Liming is an effective agricultural practice and is broadly used to ameliorate soil acidification in agricultural ecosystems. Our understanding of the impacts of lime application on the soil fungal community is scarce. In this study, we explored the responses of fungal communities to liming at two locations with decreasing soil pH in Oregon in the Pacific Northwest using high-throughput sequencing (Illumina MiSeq). Our results revealed that the location and liming did not significantly affect soil fungal diversity and richness, and the impact of soil depth on fungal diversity varied among locations. In contrast, location and soil depth had a strong effect on the structure and composition of soil fungal communities, whereas the impact of liming was much smaller, and location- and depth-dependent. Interestingly, families Lasiosphaeriaceae, Piskurozymaceae, and Sordariaceae predominated in the surface soil (0–7.5 cm) and were positively correlated with soil OM and aluminum, and negatively correlated with pH. The family Kickxellaceae which predominated in deeper soil (15–22.5 cm), had an opposite response to soil OM. Furthermore, some taxa in Ascomycota, such as Hypocreales, Peziza and Penicillium, were increased by liming at one of the locations (Moro). In conclusion, these findings suggest that fungal community structure and composition rather than fungal diversity responded to location, soil depth and liming. Compared to liming, location and depth had a stronger effect on the soil fungal community, but some specific fungal taxa shifted with lime application.

Seasonal variations in soil fungal communities and co-occurrence networks along an altitudinal gradient in the cold temperate zone of China: A case study on Oakley Mountain

Cold temperate forests carry out functions that are essential to global biogeochemical cycling and climate regulation. The biogeography of soil fungi has attracted much attention in recent years; however, the seasonal patterns of soil fungal community structure and diversity along altitudinal gradients under the unique climatic conditions at high latitudes remain unclear, which limits our insight into soil microbial interactions and the mechanisms of community assembly. In this study, Illumina MiSeq sequencing was used to investigate the spatiotemporal changes in soil fungal communities along an altitudinal gradient (from 750 m to 1420 m) on Oakley Mountain in the northern Greater Khingan Mountains. Altitude had significant impacts on the relative abundances of the dominant phyla and classes of soil fungi, and the interaction of altitude and season significantly affected the relative abundances of Ascomycota and Basidiomycota. The number of soil fungal taxa and Faith’s phylogenetic diversity index tended to monotonically decline with increasing elevation. Soil moisture, soil temperature and pH were the main factors affecting fungal community structure in May, July and September, respectively. The soil dissolved organic carbon content significantly shaped the soil fungal community composition along the altitudinal gradient throughout the growing season. Compared to that in May and July, the soil fungal network in September had more nodes and links, a higher average degree and a higher average clustering coefficient. The nine module nodes in the co-occurrence network were all Ascomycota taxa, and the identities of the keystone taxa of soil fungi in the network showed obvious seasonality. Our results demonstrated that altitude has stronger effects than season on soil fungal community structure and diversity at high latitudes. In addition, the co-occurrence network of soil fungi exhibited obvious seasonal succession, which indicated that the keystone taxa of soil fungi exhibit niche differentiation among seasons.

Effects of Land Use Changes on Soil Fungal Community Structure and Function in the Riparian Wetland Along the Downstream of the Songhua River

The aim of this study was to provide a reference for wetland resource management and ecological restoration by analyzing the influence of land use changes on the soil fungal community and its function and to identify the potential natural restoration ability of degraded riverside wetlands in the Songhua River. In July 2018, soil fungi in a natural wetland, paddy field, sand mining slash, and restoration wetland along the downstream of the Songhua River were amplified by PCR. PCR products were sequenced using the Illumina MiSeq PE300 high-throughput sequencing platform. The differences in the soil fungal community composition and function and its influencing factors were analyzed. The results showed that the α-diversity indexes of soil fungi were significantly reduced by sand mining or cultivation in the natural wetland (P<0.05). The ACE index and Chao1 index of soil fungi in the sand mining slash were significantly improved after the sand mining area was restored to a constructed wetland (P<0.05). There were significant differences in the soil fungal community structure between the paddy field and other land use types (P<0.05). The soil fungi in the riparian wetland could be divided into 16 phyla. Ascomycota, Basidiomycota, Mortierellomycota, and Rozellomycota were the dominant phyla (relative abundance>1%). Ectomycorrhizal was the main functional fungus in the natural wetland and restoration wetland with the supplementation of bryophyte parasites and lichen parasites. Litter saprotrophs and soil saprotrophs were the main functional groups of fungi in the paddy field and sand mining slash, and the relative abundances of animal pathogens and plant pathogens increased significantly in the paddy field. The diversity of the soil fungal community was significantly influenced by the soil pH, organic carbon, total nitrogen, and total phosphorus contents. Thus, resource development in the natural riparian wetlands reduced the ecosystem stability and increased the potential ecological risks.

Benzoic acid plays a part in rhizosphere microbial composition of peach seedlings grown in replanted soil

Soil micro-ecological imbalance is one of the critical factors associated with peach replanting issues. In an effort to understand the primary driving force in shaping soil microbial community, we analyzed soil nutrient, pH value, and autotoxin benzoic acid (BA) content, as well as rhizosphere microbial structure of peach seedlings grown in replanted soil (RS) and non-replanted soil (NS), both of which were collected from a same orchard. The results showed that depletion of soil nutrients, decreased soil pH, the accumulation of BA, and the deterioration of the soil microbial community were consistently detected in RS compared with NS, and led to the poor growth performance of peach seedlings. High-throughput sequencing analysis indicated that the soil microbial composition differed significantly between the NS and RS samples. Over time, the rhizosphere microbes of peach seedlings in RS and NS exhibited a similar trend of increasing bacterial richness and decreasing fungal richness. Interestingly, the NS had a high level of Bacillus and Ascobolus, whereas the RS enriched with Burkholderia and pathogenic Fusarium. Furthermore, canonical correspondence analysis revealed that soil nutrient and pH predominated the microbial composition of NS, whereas high level of soil BA played a crucial role in forming the microbial composition of RS. Altogether, this study provides a novel insight into better understanding of soil bacterial and fungal community structure in the RS, and aid in developing more effective means to alleviate the peach replant problem.

Impact of crop cultivation, nitrogen and fulvic acid on soil fungal community structure in salt-affected alluvial fluvo-aquic soil

Soil fungal communities play pivotal roles in promoting ecosystem carbon (C) and nitrogen (N) cycling, stimulating disease resistance and enhancing tolerance against salt stress of host plants. However, the impact of anthropogenic management practices on the soil fungal community structure has not yet been clarified. Using a four-consecutive-year field experiment and the quantitative polymerase chain reaction (qPCR) and Illumina MiSeq DNA sequencing methods, the single and interactive impacts of crop cultivation (CK), N fertilization (N) and fulvic acid (F) on soil fungal diversity, abundance, composition and functional groups were investigated. Consecutive crop cultivation improved soil chemical and microbial properties by reducing soil electrical conductivity (ECe) and enhancing soil organic carbon (SOC), microbial biomass carbon (MNC), and microbial biomass nitrogen (MBN). Crop cultivation had larger contribution to fungal richness and diversity than N fertilization and fulvic acid. Crop cultivation enriched mycorrhizal fungi and N fertilization enriched endophytic, saprophytic and pathogenic fungi. Structural equation modeling (SEM) revealed that soil ECe and pH indirectly influenced MBN through their adverse direct impact on OTUs, Shannon index and abundance of predominant fungal taxa. N input exhibited a positive indirect influence on MBN through enhancing abundance of Funneliformis at the genus level. Crop cultivation, N input, and fulvic acid addition in saline soil environment changed the environmental niches and drove the evolution of soil fungal community. In return, the shifts in soil fungal community composition and functional groups greatly affected soil C and N transformation with potential feedback on soil microbial activity.

Effects of Bacillus subtilis NCD-2 and broccoli residues return on potato Verticillium wilt and soil fungal community structure

Potato Verticillium wilt is an economically important disease that significantly decreases tuber yield. Biological control is an effective approach for controlling potato Verticillium wilt. The objective of this study was to evaluate the effects of treatment with Bacillus subtilis NCD-2 (BS), broccoli residues (BR), and combination among them (BB) on potato Verticillium wilt and the soil fungal community structure. Field experiments demonstrated that BS, BR and BB successfully suppressed potato Verticillium wilt, achieving control effects of 32.25%, 48.15%, and 37.85%, respectively. Compared to the untreated control, potato yield increased by 10.38%, 16.82% and 27.12% after the treatments of BS, BR and BB, respectively. Moreover, the BS treatment did not decrease the rhizosphere V. dahliae population, which was significantly decreased by BR (19.08%) and BB (30.46%). Illumina MiSeq analysis showed that soil fungal diversity in the rhizosphere was decreased under BS, BR and BB. Principal component and heatmap analyses showed that BS exerted a similar effect on the fungal community structure to the blank control. However, BR and BB greatly changed the fungal community structure. Moreover, the relative abundance of beneficial microbes such as Chaetomium and Mortierella was higher in the BS and BB soils than in the control. Redundancy analysis (RDA) showed that the fungal community structure under BR and BB was positively correlated with SOM, pH, AP and IP, while the opposite trend was observed under BS. The results suggested that BS seed treatment and BR return could be a useful strategy for potato production in sustainable agriculture; this research may provide a theoretical basis for understanding the mechanism of the ecological control of potato Verticillium wilt.

Cover Cropping Impacts Soil Microbial Communities and Functions in Mango Orchards

Soil microbes play critical roles in nutrient cycling, net primary production, food safety, and climate change in terrestrial ecosystems, yet their responses to cover cropping in agroforestry ecosystems remain unknown. Here, we conducted a field experiment to assess how changes in cover cropping with sown grass strips affect the fruit yields and quality, community composition, and diversity of soil microbial taxa in a mango orchard. The results showed that two-year cover cropping increased mango fruit yields and the contents of soluble solids. Cover cropping enhanced soil fungal diversity rather than soil bacterial diversity. Although cover cropping had no significant effects on soil bacterial diversity, it significantly influenced soil bacterial community compositions. These variations in the structures of soil fungal and bacterial communities were largely driven by soil nitrogen, which positively or negatively affected the relative abundance of both bacterial and fungal taxa. Cover cropping also altered fungal guilds, which enhanced the proportion of pathotrophic fungi and decreased saprotrophic fungi. The increase in fungal diversity and alterations in fungal guilds might be the main factors to consider for increasing mango fruit yields and quality. Our results indicate that cover cropping affects mango fruit yields and quality via alterations in soil fungal diversity, which bridges a critical gap in our understanding of the linkages between soil biodiversity and fruit quality in response to cover cropping in orchard ecosystems.

Soil Fungal Community Structure and Functional Diversity in a Copper Tailing Dam and Its Surrounding Areas

Soil fungal communities are reconstructed under heavy metal stress. This study was conducted to explore the structural and functional diversity of soil fungal communities under different land-use patterns, namely grassland and farmland, in 15-year-old or 10-year-old poplar plantations (Populus deltoides cv. 'zhonghuahongye') near the Shibahe copper tailing dam and the surrounding area, located in Yuanqu County, Shanxi. The results indicated that the abundance and diversity of fungal communities were the highest in the 15-year-old poplar plantation and lowest in the grassland on the tailing dam. The dominant fungal groups in the study area were Ascomycota, Basidiomycota, and Mortierellomycota. The Ascomycota members were the most abundant at all four sampling sites, reaching 92.92% of the fungal community in the grassland on the tailing dam. The highest functional diversity of carbon utilization was found in the soil fungal communities of the 15-year-old poplar plantations; moreover, the diversity in the grassland on the tailing dam was significantly higher than that in the farmland and in the 10-year-old poplar plantation. Meanwhile, we also observed the highest glucoside carbon source utilization efficiency in the grassland. Notably, the correlation analysis revealed that Ascomycota was significantly correlated with the utilization efficiency of the glucoside carbon source in our study area. Moreover, the soil total nitrogen content, but not the soil heavy metal content, was significantly correlated with the abundance of the soil fungal community. There were significant correlations between the cadmium and arsenic contents and the soil fungal community diversity indices. Our results indicated that the soil fungal communities were more influenced by soil fertility and land use than by the soil heavy metal content. This study underlies the application of soil fungal communities in soil remediation of heavy metal-contaminated areas.

Effects of Living Cover on the Soil Microbial Communities and Ecosystem Functions of Hazelnut Orchards.

Living cover is an important management measure for orchards in China, and has certain influences on soil properties, microorganisms, and the micro-ecological environment. However, there are few studies on the effects of living cover on the soil changes in hazelnut orchards. In this study, we compared the soils of living cover treatments with Vulpia myuros and the soils of no cover treatments, and analyzed the observed changes in soil properties, microorganisms, and microbial functions by using high-throughput ITS rDNA and 16S rRNA gene Illumina sequencing. The results demonstrated that the total organic carbon content in the 20–40 cm deep soils under the living cover treatments increased by 32.87 and 14.82% in May and July, respectively, compared with those under the no cover treatments. The living cover treatment with V. myuros also significantly increased the contents of total phosphorus (TP), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) in the soil samples. Moreover, the influence of seasons was not as significant as that of soil depth. The living cover treatment also significantly improved the soil enzyme activity levels. The results demonstrated that Ascomycota, Mortierellomycota and Basidiomycota were the dominant fungal phyla in all samples, while Proteobacteria, Actinobacteria, Acidobacteria, Firmicutes, and Chloroflexi were the dominant bacterial phyla, but the different treatments impacted the compositions of fungal and bacterial communities. Principal component analysis (PCA) showed that living cover with V. myuros significantly changed the soil fungal community structures whereas the bacterial community structures may be more sensitive to seasonal changes. At the microbial functional level, the living cover treatment increased the fungal operational taxonomic units (OTUs) of symbiotrophs and decreased that of pathotrophs. According to this study, we believe that the application of a living cover with V. myuros has a favorable regulating influence on soil properties, microbial communities and microbial function. This treatment can also reduce the use of herbicides, reduce the cost of orchard management, and store more carbon underground to achieve sustainable intensification of production in hazelnut orchards, so it can be considered as a management measure for hazelnut orchards.

High Fungal Diversity but Low Seasonal Dynamics and Ectomycorrhizal Abundance in a Mountain Beech Forest

Forests on steep slopes constitute a significant proportion of European mountain areas and are important as production and protection forests. This study describes the soil fungal community structure in a European beech-dominated mountain forest stands in the Northern Calcareous Alps and investigates how it is determined by season and soil properties. Samples were collected at high spatial resolution in an area of ca. 100 m × 700 m in May (spring) and August (summer). Illumina MiSeq high-throughput sequencing of the ITS2-region revealed distinct patterns for the soil fungal communities. In contrast to other studies from temperate European beech forest stands, Ascomycota dominated the highly diverse fungal community, while ectomycorrhizal fungi were of lower abundance. Russulaceae, which are often among the dominant ectomycorrhizal fungi associated with European beech, were absent from all samples. Potentially plant pathogenic fungi were more prevalent than previously reported. Only subtle seasonal differences were found between fungal communities in spring and summer. Especially, dominant saprotrophic taxa were largely unaffected by season, while slightly stronger effects were observed for ectomycorrhizal fungi. Soil characteristics like pH and organic carbon content, on the other hand, strongly shaped abundant taxa among the saprotrophic fungal community.

Soil nutrient supply and tree species drive changes in soil microbial communities during the transformation of a multi-generation Eucalyptus plantation

Intensive management of Eucalyptus plantations has caused several social/environmental issues, including the concern over transformation of monoculture plantation cutover area. However, how different transformation patterns of Eucalyptus plantations affect soil microbial communities and their functions is unclear. In this study, the effects of different transformation patterns on structure and potential function of soil bacterial and fungal communities were evaluated. Soil chemical properties and acid phosphatase, urease, and catalase activities were also measured. In the third-generation monoculture Eucalyptus plantations, soil organic matter, nutrient contents, and microbial biomass decreased significantly and the relative abundance of oligotrophic bacteria (Chloroflexi) and symbiotic fungi (ectomycorrhizae) increased significantly compare with CK. However, in the Eucalyptus × Manglietia glauca Blume mixed plantation (E × M) and a Manglietia glauca Blume plantation (Manglietia), soil fertility (e.g., soil organic matter, total nitrogen, total phosphorus, and total potassium) improved, especially in E × M. In addition, soil acid phosphatase (0.30 mg∙g−1∙h−1) and catalase (0.66 mg∙g−1∙h−1) activities and the bacterial gene copies:fungal gene copies ratio (46.70) increased significantly in E × M compared with those in the monoculture plantations. The relative abundance of copiotrophic bacteria (Actinobacteria) and nitrogen cycle-associated bacteria (orders Rhizobiales and Frankiales) increased significantly in E × M. The abiotic factors soil available nitrogen and available zinc were the significant drivers of soil bacterial community structure, whereas the structure of fungal communities was most affected by tree species, in addition to soil pH and available copper. The results indicated that the E × M transformation pattern in the cutover area of Eucalyptus plantations had a significant beneficial effect on the soil fertility. The study also indicated that young plantations with Eucalyptus species have specific requirements for soil available phosphorus, available potassium, and available magnesium. Thus, increasing the supply of these nutrients during plantation development may have a positive effect on the sustainable management of plantations.

Soil microbial community and network changes after long-term use of plastic mulch and nitrogen fertilization on semiarid farmland

Soil microbes are crucial for improving soil quality and productivity. Plastic film mulch (FM), in conjunction with fertilization, has significantly improved crop yields over vast areas of dryland production. However, how these practices affect soil microbial communities, especially as regards co-occurrence patterns within microbial taxa, is unclear. The objective of this study was to determine the effects of 10 years of FM and four nitrogen (N) fertilization rates [0 (N0), 100 (N100), 250 (N250), and 400 (N400) kg N ha−1] on soil bacterial and fungal diversity, community structure, composition, and the co-occurrence network in a rainfed maize (Zea mays L.) field on the Loess Plateau of China. Results showed that N fertilization and FM did not affect soil microbial biomass carbon, but these practices changed the soil bacterial and fungal community structures. The bacterial community structure was dominantly affected by N fertilization, owing to the increased soil N content and decreased soil pH, which reduced bacterial community diversity and altered the relative abundance of some copiotrophic/oligotrophic taxa (e.g., Gemmatimonadetes, Acidobacteria, Rokubacteria, and Planctomycetes). Plastic mulch played a greater role in regulating the fungal community structure, primarily because FM increased soil moisture and promoted soil organic matter decomposition, thereby reducing fungal richness and altered the relative abundance of Chytridiomycota, Mortierellomycota, Glomeromycota, and Mucoromycota. Moreover, FM mediated the effects of N fertilization by reducing soil N content, and then increased the N threshold that caused changes in microbial structure. Network analysis indicated that FM caused an unstable co-occurrence network with fewer positive and negative links, while N fertilization increased both positive and negative (except N400) links, indicating enhanced cooperation and competition among microbes. These results indicate that long-term plastic mulch and high N fertilization could result in risk for soil quality in terms of soil microbial community structure and stability, suggesting that developing new management strategies is necessary to sustain dryland productivity.

Immediate and legacy effects of snow exclusion on soil fungal diversity and community composition

BackgroundSoil fungi play crucial roles in ecosystem functions. However, how snow cover change associated with winter warming affects soil fungal communities remains unclear in the Tibetan forest.MethodsWe conducted a snow manipulation experiment to explore immediate and legacy effects of snow exclusion on soil fungal community diversity and composition in a spruce forest on the eastern Tibetan Plateau. Soil fungal communities were performed by the high throughput sequencing of gene-fragments.ResultsAscomycota and Basidiomycota were the two dominant fungal phyla and Archaeorhizomyces, Aspergillus and Amanita were the three most common genera across seasons and snow manipulations. Snow exclusion did not affect the diversity and structure of soil fungal community in both snow-covered and snow-free seasons. However, the relative abundance of some fungal communities was different among seasons. Soil fungal groups were correlated with environmental factors (i.e., temperature and moisture) and soil biochemical variables (i.e., ammonium and enzyme).ConclusionsThese results suggest that the season-driven variations had stronger impacts on soil fungal community than short-term snow cover change. Such findings may have important implications for soil microbial processes in Tibetan forests experiencing significant decreases in snowfall.

Aboveground vegetation and soil physicochemical properties jointly drive the shift of soil microbial community during subalpine secondary succession in southwest China

Based on long-term ecological research, microorganisms are sensitive to environmental changes in the process of ecosystem succession. However, few works have focused on the response of different groups of soil microorganisms to subalpine secondary succession and the driving forces behind the stepwise community development. To explore the changes in the microbial community structure and the driving mechanisms, we selected three replicated secondary succession gradients consisting of grass, shrub, different secondary forests (picea, pine and birch) and primary forest in a subalpine area in southwestern China. A high-throughput sequencing method was used to compare differences in the soil fungal and bacterial community structures. In combination with aboveground plant diversity and soil properties, the different mechanisms controlling the soil microbial community were revealed by the Mantel test. A two-way correlation network was also used to explore the connections among stages. The results show that the change in bacterial and fungal community structure was obvious, and these changes of bacteria were significantly correlated with soil acid phosphatase, LAP, soil moisture and aboveground vegetation communities during succession development in subalpine forests. Moreover, the fungal community was related to soil organic carbon, nitrogen, vegetation diversity, abundance and community structure. We also found that different dominant fungi play crucial roles in the succession sequence, and the relationship between soil microbes and vegetation is gradually simplified and stabilized. Our work suggests that both the relatively stable bacterial communities and the significantly changing fungal communities are notably associated with abiotic and biotic factors in secondary succession. As the ecosystem evolves, the dominant fungi obviously respond to succession and can successively establish close relationships with plants. Consequently, our results have important implications for understanding the driving mechanisms that control the soil microbial community during subalpine forest secondary succession.