Effects of Simulated Warming on Soil Fungal Community Composition and Diversity

Soil fungi play an integral and essential role in maintaining soil ecosystem functions. The understanding of altitude variations and their drivers of soil fungal community composition and diversity remains relatively unclear. Mountains provide an open, natural platform for studying how the soil fungal community responds to climatic variability at a short altitude distance. Using the Illumina MiSeq high-throughput sequencing technique, we examined soil fungal community composition and diversity among seven vegetation types (dry valley shrub, valley-mountain ecotone broadleaved mixed forest, subalpine broadleaved mixed forest, subalpine coniferous-broadleaved mixed forest, subalpine coniferous forest, alpine shrub meadow, alpine meadow) along a 2582 m altitude gradient in the alpine–gorge region on the eastern Qinghai–Tibetan Plateau. Ascomycota (47.72%), Basidiomycota (36.58%), and Mortierellomycota (12.14%) were the top three soil fungal dominant phyla in all samples. Soil fungal community composition differed significantly among the seven vegetation types along altitude gradients. The α-diversity of soil total fungi and symbiotic fungi had a distinct hollow pattern, while saprophytic fungi and pathogenic fungi showed no obvious pattern along altitude gradients. The β-diversity of soil total fungi, symbiotic fungi, saprophytic fungi, and pathogenic fungi was derived mainly from species turnover processes and exhibited a significant altitude distance-decay pattern. Soil properties explained 31.27−34.91% of variation in soil fungal (total and trophic modes) community composition along altitude gradients, and the effects of soil nutrients on fungal community composition varied by trophic modes. Soil pH was the main factor affecting α-diversity of soil fungi along altitude gradients. The β-diversity and turnover components of soil total fungi and saprophytic fungi were affected by soil properties and geographic distance, while those of symbiotic fungi and pathogenic fungi were affected only by soil properties. This study deepens our knowledge regarding altitude variations and their drivers of soil fungal community composition and diversity, and confirms that the effects of soil properties on soil fungal community composition and diversity vary by trophic modes along altitude gradients in the alpine–gorge region.

Different fertilization regimes can substantially influence soil fungal community composition, yet fewer studies try to control for the effects of nitrogen input. Here, we investigated the impact of fertilization with equal nitrogen upon soil properties and soil fungal diversity and community composition in the North China Plain in a long-term field experiment. Long-term (32 years) fertilization regimes were applied with equal amounts of nitrogen: no chemical fertilizer or organic manure; chemical fertilization only; organic manure fertilization only, and; combination of 1/2 chemical fertilizer and 1/2 organic manure. Then we investigated the influence of these four fertilization regimes to soil properties, fungal diversity and community composition. The results showed that applying organic manure significantly influenced soil properties. Illumina MiSeq sequencing and its analysis revealed that organic manure fertilization significantly changed soil fungal alpha diversity, but chemical fertilization did not. Although soil fungal community composition did not differ significantly among all the fertilization regimes at the phylum and class levels, they did show differences in the abundance of dominant fungi. Yet at the genus level, soil fungal community composition, abundance, and beta diversity was affected by all fertilization regimes. Application of organic manure also reduced the abundance of soil-born fungal pathogens such as Fusarium. Our results suggest that long-term application of organic manure could markedly improve soil properties, altering soil fungal community composition and its diversity. Moreover, organic manure fertilization could limit soil-born fungal diseases, to further contribute to soil ecosystem sustainability.

Soil fungi are essential to soil microorganisms that play an important role in the ecosystem's soil carbon cycle and mineral nutrient transformation. Understanding the structural characteristics and diversity of soil fungal communities helps understand the health of forest ecosystems. The transition from tropical rainforest to artificial forest greatly impacts the composition and diversity of fungal communities. Hainan Limushan tropical rainforest National Park has a large area of artificial forests. Ecologists have conducted in-depth studies on the succession of animals and plants to regenerate tropical rainforests. There are few reports on the diversity of soil fungi and its influencing factors in the succession of tropical rainforests in Limu Mountain. In this study, 44 soil samples from five different stands were collected in the tropical rainforest of Limushan, Hainan. High-throughput sequencing of rDNA in its region was used to analyze fungal communities and study their α and β diversity. Analysis of variance and multiple regression models was used to analyze soil variables and fungal functional groups to determine the effects of interaction between fungi and environmental factors. A total of 273,996 reads and 1290 operational taxonomic units (OTUs) were obtained, belonging to 418 species, 325 genera, 159 families, eight phyla, 30 classes, and 73 orders. The results showed that the composition of soil fungal communities in the five stands was similar, with ascomycetes accounting for 70.5% and basidiomycetes accounting for 14.7%. α and β diversity analysis showed that soil fungi in Limushan tropical rainforest had high abundance and diversity. Multiple regression analysis between soil variables and functional groups showed that organic matter, TN, TP, TK, and AK were excellent predictors for soil fungi. TP was the strongest predictor in all functional groups except soil saprotroph. Organic matter and total nitrogen were the strongest predictors of soil rot. The transformation from tropical rainforest to artificial forest in Limushan did not change the soil fungal community structure, but the richness and diversity of soil fungi changed. The forest transformation did not lead to decreased soil fungal abundance and diversity. Different vegetation types and soil properties affect the diversity of soil fungal communities. We found that Caribbean pine plantations can improve soil fungal diversity, while long-term Eucalyptus spp. plantations may reduce soil fungal diversity.

Whether and how seasonality of environmental variables impacts the spatial variability of soil fungal communities remain poorly understood. We assessed soil fungal diversity and community composition of five Chinese zonal forests along a latitudinal gradient spanning 23°N to 42°N in three seasons to address these questions. We found that soil fungal diversity increased linearly or parabolically with latitude. The seasonal variations in fungal diversity were more distinguishable in three temperate deciduous forests than in two subtropical evergreen forests. Soil fungal diversity was mainly correlated with edaphic factors such as pH and nutrient contents. Both latitude and its interactions with season also imposed significant impacts on soil fungal community composition (FCC), but the effects of latitude were stronger than those of season. Vegetational properties such as plant diversity and forest age were the dominant factors affecting FCC in the subtropical evergreen forests while edaphic properties were the dominant ones in the temperate deciduous forests. Our results indicate that latitudinal variation patterns of soil fungal diversity and FCC may differ among seasons. The stronger effect of latitude relative to that of season suggests a more important influence by the spatial than temporal heterogeneity in shaping soil fungal communities across zonal forests.

The objective of this study was to analyze the responses of the soil fungal community to the afforestation of cropland with single and mixed tree species. We investigated changes in soil fungal community composition, diversity, structure and functional groups in the topsoil (0–20 cm) following afforestation. Six forest types were analyzed in this study: Robinia pseudoacacia (RP), Platycladus orientalis (PO), Pinus tabuliformis (PT), Robinia pseudoacacia + Platycladus orientalis (RPPO), Robinia pseudoacacia + Pinus tabuliformis (RPPT), and Platycladus orientalis + Pinus tabuliformis (POPT). Soil fungal community composition and diversity significantly varied among cropland and forestland samples. Afforestation generally reduced soil fungal diversity and altered functional groups, and these variations were mainly mediated by tree species. Rare genera play an important role in the soil fungal network among cropland and forestland samples. Soil available phosphorus (AP) explained the largest portion of the variance in the soil fungal community. Soil available nutrients and microclimate were significantly associated with soil fungal diversity and richness. Our observations indicate that afforestation of cropland fundamentally restructures soil fungal community composition, structure, diversity and functional groups. Nutrient availability was a principal factor regulating fungal community composition following afforestation.

Soil fungal communities play a critical role in ecosystem carbon (C) and nitrogen (N) cycling. Although the effect of plant invasions on ecosystem C and N cycling is well established, its impact on soil fungal communities is not fully understood. The objective of this study was therefore to understand the variations in soil fungal communities as affected by plant invasion, and the mechanisms that drive these changes. We examined the impacts of invasive Spartina alternifolia Loisel. (SA) on soil fungal abundance, diversity, community composition, trophic modes and functional groups in comparison with bare flat (BF) and native Suaeda salsa (Linn.) Pall. (SS), Scirpus mariqueter Tang et Wang (SM), and Phragmites australis (Cav.) Trin. ex Steud. (PA) communities in coastal salt marshes of eastern China, based on analyses of the quantitative polymerase chain reaction (qPCR) and Illumina MiSeq DNA sequences of fungal internal transcribed spacer (ITS) region. SA invasion increased the soil fungal abundance and diversity compared to BF, SS, SM, and PA soils. The increased soil fungal abundance and diversity were highly related to soil organic carbon (C) and nitrogen (N), water-soluble organic carbon (WSOC), litter C:N ratio, and root C:N ratio. Soil fungal community composition was shifted following SA invasion. Specifically, SA invasion significantly enhanced the relative abundance of Basidiomycota, and reduced the relative abundance of Ascomycota compared with BF, SS, SM, and PA soils. Additionally, SA invasion changed soil fungal trophic modes and functional groups. The relative abundance of saprotrophic fungi significantly increased, while the relative abundances of symbiotic and pathotrophic fungi decreased following SA invasion. Our data revealed that SA invasion altered soil fungal abundance, diversity, community composition, trophic modes and functional groups, which were primarily driven by the quality and quantity of plant residues, soil nutrition substrates, as well as soil physicochemical properties. The changes in soil fungal communities, especially their trophic modes and functional groups following SA invasion would greatly affect soil C and N decomposition and accumulation with potential feedback on climate change.

Seasonal variations of soil fungal diversity and communities in subalpine coniferous and broadleaved forests

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.

Diverse compost products influence soil bacterial and fungal community diversity in a potato crop production system

Effects of microtopography on soil fungal community diversity, composition, and assembly in a subtropical monsoon evergreen broadleaf forest of Southwest China

柏木人工林林窗位置对香椿细根分解及土壤真菌群落多样性的影响

Thinning is an important silvicultural practice for improving the productivity and wood production in plantation forest. Different intensities of thinning management can affect tree growth and alter soil nutrient effectiveness, thus affecting soil fungal community structure and diversity. Our objective is to determine the soil factors and their regulatory mechanisms that influence stand growth by thinning, and to provide data to support the establishment of large diameter timber cultivation technology for Picea koraiensis. In this study, we conducted medium- and high-intensity thinning in 43a P. koraiensis plantation middle-aged forests and investigated the growth indexes, soil physicochemical properties, and fungal community diversity in rhizosphere and non-rhizosphere soils of the stands after thinning at different densities (904 plants/ha for control, 644 plants/ha for 30% thinning intensity, and 477 plants/ha for 50% thinning intensity). The results showed that all growth indicators (annual growth of tree height, diameter at breast height, height under live branches and crown width) of the plantation after high-intensity thinning (477 plants/ha) were higher than those of the control (no thinning, significant) and medium-intensity thinning (644 plants/ha). Mycorrhizal infection rate was higher at the beginning of the growing season than at the end of the growing season, and increased slightly with decreasing stand density. Compared to the control, all medium- and high-intensity thinning treatments significantly improved soil nutrient content (P < 0.05), including total carbon, total nitrogen, total phosphorus, total potassium, Available phosphorus and Available potassium. Fungal diversity was higher but lower in abundance than the control in both rhizosphere and non-rhizosphere soils after thinning. The number of OTUs and fungal richness and diversity indices of non-rhizosphere soil fungi were higher than those of rhizosphere soil fungi. In conclusion, this study provides new evidence that reasonable intercalation can increase the radial and vertical growth of P. koraiensis plantation forests and promote the diversity of subsurface soil fungal communities. It is shown that thinning intensity regulates biogeochemical cycles in P. koraiensis plantation ecosystems by affecting soil nutrients and fungal community structure. Therefore, 50% thinning intensity can be used to increase timber production in plantation forests during large diameter timber cultivation of P. koraiensis and improve predictions associated with achieving long-term forest management strategies.

Increasing the frequency of pulses in crop rotations reduces soil fungal diversity and increases the proportion of fungal pathotrophs in a semiarid agroecosystem

To investigate the structure, diversity, and function of different paddy soil fungal communities and the factors affecting them in typical paddy cropping areas in China, five typical Chinese paddy soils were selected in this study, and the composition and diversity of soil fungal communities were comparatively analyzed using high-throughput sequencing technology and functionally predicted using the FUNGuild microecological tool. The results showed that： ① The fungal community diversity of soil samples from Heilongjiang （HLJ） was significantly lower than that of the other four regions （P<0.05）； the highest fungal community richness was found in paddy soils from Yunnan （YN）, which was significantly higher than that of the other regions （P<0.05）； and the soil samples from Hainan （HN）, Jiangxi （JX）, and Shandong （SD） were relatively close to each other. The highest average relative abundance at the level of the five typical paddy phyla was Ascomycota, and the genus with the highest average relative abundance was Tausonia. ② Fungi had the largest proportion of saprophytic trophic types, and their corresponding environmental functions were stronger. ③ The species abundance of soil fungi was highly significantly correlated with soil TP, EC, and BD （P<0.01）, and redundancy analyses also showed that soil TP was the main driver of the fungal community as well as the saprophytic functional taxa. The above results showed that the soil fungal community diversity and structure varied greatly among samples, and the relative abundance of fungal genera was affected by soil physical and chemical properties and altered the fungal community structure in paddy fields. The development of this study will provide theoretical references for the sustainable management based on fungal diversity and function of paddy fields.

Decay of fallen wood and elevation affects soil fungal community assembly and indirectly controls community diversity