Ectomycorrhizal Trees Research Articles

Nitrogen addition accelerates aboveground biomass sequestration in old-growth forests by stimulating ectomycorrhizal tree growth.

Examining whether nitrogen (N) enrichment promotes secondary tree growth in both young (YF) and old-growth forests (OF) is crucial. This will help determine how N addition influences plant carbon sequestration across successional phases in temperate forests. We conducted an eight-year N addition experiment (0, 25, 50, 75kgN ha-1 yr-1) in YF and OF in northeast China to investigate the effects of enhanced in situ N deposition on tree growth. Our results indicated that N addition accelerated the accumulation of annual mean aboveground biomass (ΔAGB) of trees only in OF. Specifically, for the species co-occurring in both YF and OF plots, their ΔAGB in OF peaked under the medium N treatment (3.69Mgha-1 yr-1), which was 2.3 times higher than that of YF (1.58Mgha-1 yr-1). Regarding mycorrhizal types, only the ΔAGB of EcM-associated trees peaked under the high N treatment (2.81Mgha-1 yr-1), increasing by 126.6% compared to the control (1.24Mgha-1 yr-1). This increase in biomass primarily came from large trees with a DBH ≥15cm, most of which are EcM -associated species, such as Pinus koraiensis. In conclusion, continuous N addition increases nutrient supply and alleviates N limitation in old growth forest, leading to faster biomass accumulation. The growth of large-diameter trees with EcM-associated may contribute significantly to aboveground biomass accmulation under N addition. Nutrient limitation is dependent on stand age, mycorrhizal type and size, so these factors must be considered when assessing forest nutrient limitations.

Mycorrhiza‐dependent drivers of the positive rhizosphere effects on the temperature sensitivity of soil microbial respiration in subtropical forests

Abstract Tree roots and their fungal symbionts mediate the response of rhizosphere soil organic carbon (SOC) decomposition to climate warming, specifically the temperature sensitivity of soil microbial respiration (Q10), which is a critical parameter for projecting the magnitude of terrestrial soil C‐climate feedbacks. However, the intensity of the rhizosphere effects (RE; rhizosphere soils vs. bulk soils) on Q10 in forest soils associated with different mycorrhizal groups and their seasonal dynamics are poorly understood. Here, we selected nine tree species associated with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi in subtropical forests of China and collected bulk soil and rhizosphere soil in both the warm and cold seasons to explore the RE on Q10, respectively. Our results showed a positive RE on Q10 (ranging from 20.1% to 87.5%) for all tree species, independent of the season. For EM tree species, the RE on Q10 was 64.5% higher in the warm season and 44.4% higher in the cold season, compared with AM tree species. The RE on Q10 of AM and EM tree species was 44.8% and 65.0% larger in the warm season than that in the cold season, respectively. Fine root traits (including biomass, the carbon‐to‐nitrogen ratio, and soluble sugar content) predominantly controlled the RE on Q10 in AM‐dominated forests, whereas the RE on soil properties (such as and C availability) dominantly governed the RE on Q10 in EM‐dominated forests. Furthermore, the RE on Q10 was also positively correlated with the RE on soil microbial phospholipid fatty acids in both AM‐ and EM‐dominated forests. These findings suggest that rhizosphere soils in EM‐dominated forests are more susceptible to C losses under climate warming than those in AM‐dominated forests, compared with their respective bulk soils, potentially limiting rhizosphere SOC sequestration. The greater vulnerability of EM‐dominated forests underscores the importance of accounting for root–soil interactions, mycorrhizal associations, and seasonal dynamics in C‐climate models to improve predictions of SOC cycling and its feedback to global warming. Read the free Plain Language Summary for this article on the Journal blog.

Nitrogen deposition changes the root nutrient uptake strategies by affecting microbial diversity of the rhizosphere

Despite the acknowledged importance of rhizosphere fungi in ecosystem functioning, their role in mediating the effects of environmental changes on plant root nutrient uptake strategies remains inadequately understood. To address this gap, long-term nitrogen addition field experiments were conducted to investigate how rhizosphere fungal diversity influences specific root length, a pivotal indicator of plant nutrient uptake rate. The results of the study showed that nitrogen addition significantly augmented specific root length and rhizosphere fungal diversity in both arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species. However, the effects on rhizosphere fungal diversity differed markedly between the two mycorrhizal types. In AM tree species, nitrogen addition decreased rhizosphere beneficial fungal diversity while increasing the diversity of pathogenic fungi. Conversely, ECM tree species exhibited an increase in rhizosphere beneficial fungal diversity and a reduction in pathogenic fungal diversity under nitrogen addition. Furthermore, we identified a positive correlation between the diversity of rhizosphere pathogens and specific root length under nitrogen addition, while a negative correlation was observed under the control. Structural equation modeling further revealed that the indirect effects of nitrogen addition on SRL were mediated through changes in the diversity of rhizosphere beneficial fungi. These findings suggest that nitrogen addition not only directly influences SRL but also exerts significant indirect effects by altering the microbial composition of the rhizosphere. In summary, the study underscores the substantial impact of long-term nitrogen addition on the interactive mechanism of plant physiological characteristics, mediated by pathogenic and beneficial fungi in the rhizosphere of temperate forests.

Long-Term Soil Warming Drives Different Belowground Responses in Arbuscular Mycorrhizal and Ectomycorrhizal Trees.

The ability of trees to acquire soil nutrients under future climate conditions will influence forest composition and function in a warmer world. Rarely are multiple belowground carbon allocation pathways measured simultaneously in large global change experiments, restricting our understanding of how trees may shift their allocation of resources to different nutrient acquisition mechanisms under future climates. Leveraging a 20-year soil warming experiment, we show that ectomycorrhizal (EM) trees reduce mycorrhizal colonization and root exudation while increasing fine root biomass, while arbuscular mycorrhizal (AM) trees largely maintained their belowground carbon allocation patterns in warmer soils. We suggest that AM trees may be better adapted to thrive under global warming due to higher rates of nitrogen mineralization in warmer soils and the ability of their mycorrhizal symbiont to acquire mineralized inorganic nutrients, whereas EM trees may need to alter their belowground carbon allocation patterns to remain competitive as global temperatures rise.

Variation in functional traits among different mycorrhizal types and life history stages of temperate broadleaf tree species

Exploring the variation in functional traits in plants from different perspectives not only helps reveal the adaptation of plants to their environment but also reflects the ecological strategies of plants. In this study, three species of arbuscular mycorrhizal (AM) trees and three species of ectomycorrhizal (EM) trees were selected in the Heilongjiang Liangshui National Nature Reserve. To investigate the similarities and differences between the functional traits of the two mycorrhizal types of trees at different life history stages, hydraulic traits, anatomical traits, leaf functional traits, and stoichiometry of each species were measured at different life history stages. Traits such as mean vessel area, hydraulic weighted vessel diameter and nitrogen content appeared to be relatively important traits in this study, and all traits were more strongly correlated in AM trees. The sapwood-specific hydraulic conductivity, leaf-specific hydraulic conductivity, vessel density, vessel lumen fraction, nitrogen content and phosphorus content of EM species were significantly higher than those of AM species, while the total vessel area, mean vessel area, hydraulic weighted vessel diameter and density of primary leaf veins of EM species were significantly lower than those of AM species. The leaf mass per area and leaf dry matter content of saplings were significantly lower than those of juvenile trees and adult trees. Most of the trait variation interspecific and intraspecific, and the variability of hydraulic and anatomical traits such as sapwood-specific hydraulic conductivity, leaf-specific hydraulic conductivity, vessel density and total vessel area was relatively large. Leaf dry matter content, hydraulic weighted vessel diameter, vessel density and the vessel lumen fraction contributed significantly to whole branch hydraulic conductivity. It is evident that plastic adjustment and synergistic variation in functional traits are important mechanisms by which plants with different mycorrhizal types and at different life history stages can adapt to different environments.

Mycorrhizal Types Regulate Tree Spatial Associations in Temperate Forests: Ectomycorrhizal Trees Might Favour Species Coexistence.

In temperate mixed forests, dominant ectomycorrhizal (EM) tree species usually coexist with diverse arbuscular mycorrhizal (AM) understorey tree species. Here, we investigated the spatial associations between AM and EM trees in two > 20 ha temperate forest mega-plots to better understand the observed 'EM-dominant versus AM-diverse' coexistence. Overall, we found that positive spatial associations (e.g., facilitation) were mostly related to EM trees, while negative spatial associations (e.g., inhibition) were mainly related to AM trees. Because adult EM trees tended to facilitate surrounding AM and EM saplings and other EM adults in these two forests, facilitation hotspots that stabilize AM-EM tree coexistence should be centred around EM tree species rather than around AM tree species. Together, we propose a novel EM-stabilization mechanism, which emphasises how, despite some species-specific variation, EM tree species foster 'EM-dominant versus AM-diverse' coexistence in temperate mixed forests by facilitating other trees.

Tilia trees are preferred hosts of several ectomycorrhizal Ascomycota – New insights supported by the first community study of the endemic Tilia kiusiana

Asia is the center of Tilia (Malvaceae) species diversity. However, the ectomycorrhizal (ECM) relations of Asian Tilia are scarcely studied. This study provides the first description of ECM communities of Tilia kiusiana, a rare tree endemic to southwestern Japan. Across the natural distribution of T. kiusiana, ECM fungal communities hosted by the species were investigated in three study sites: Hyōgo (H) and Yamaguchi (Y) on Honshu Island, and Ōita (O) on Kyushu Island. Using molecular methods, T. kiusiana was revealed to host a high diversity of fungi belonging to 25 ECM lineages (16, 17, and 14 lineages on sites H, Y, and O, respectively). The ECM communities of T. kiusiana and the previously studied endemic T. japonica were compared to the available data on other ECM tree genera in Japan, revealing that three Ascomycota ECM lineages (/genea-humaria, marcelleina-peziza gerardii, /tuber-helvella) show a preference towards Tilia hosts. While the total lineage richness did not differ among the compared host tree genera, Tilia communities exhibited higher effective lineage richness at higher (less sensitive to rare taxa) diversity orders. Despite their relative rarity, Tilia trees might play an important role in mixed forests: maintaining the diversity of ECM Ascomycota and potentially buffering the ECM fungal biodiversity loss in cases of ECM tree host diversity decline.

The interactive effect of tree mycorrhizal type, mycorrhizal type mixture and tree diversity shapes rooting zone soil fungal communities in temperate forest ecosystems

Abstract The underlying processes of plant‐microbe associations particularly their interactions with their mycorrhizal fungal partners have been extensively studied. However, considerably less is known about the consequences of tree‐tree interactions on rooting zone soil microbiota when tree species of different mycorrhizal type (myco‐type) grow together as mono and mixed myco‐type mixtures along a tree diversity gradient. Using the MyDiv tree diversity experiment, where arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) trees and their mixtures were planted in monocultures, two‐species and four‐species mixture plots, we investigated the interplay of target tree myco‐type, myco‐type mixture, tree diversity and rooting zone compartment (target tree dominated and its interaction zones with neighbour trees) on the rooting zone soil mycobiota employing meta‐barcoding of the ITS2 rDNA fragment of the fungal internal transcribed spacer (ITS). Our results revealed significant individual and interaction effects of tree myco‐type, myco‐type mixture and tree diversity but not rooting zone compartment on the fungal taxonomic and functional alpha and beta diversity. This implies intermingling of roots of target and neighbouring tree species there by reducing the target tree species effect in its rooting zone. As tree diversity increases, we found convergence of the fungal community in general, where the fungal community dissimilarity varies depending on the co‐existing tree species myco‐type and tree species diversity. Furthermore, the fungal community composition in the two and four species mixtures were consistently influenced by soil pH, whereas in the mixed multi‐species stands basal respiration, N, PO4−, NO3− were found to be equally important unlike in AM and EcM multi‐species stands. Comparative analysis of the fungal taxa specialisation between mono and mixed myco‐type multi‐species stands revealed that the mixed myco‐type plots shared 23.5% (AM) and 19.7% (EcM) of the generalist fungal communities However, the percentage of specialised fungal community in mixed myco‐type plots (13.2%) was significantly higher as compared to EcM (9.5%), and significantly lower (9%) as compared to AM (11.7%) plots, resulting in myco‐type and myco‐type mixture specific fungal communities and functional guild patterns Our results provide novel insights on the significance of tree species and its co‐existing trees preferred mycorrhizal association in shaping the target tree rooting zone soil mycobiome along a tree diversity gradient. Furthermore, it highlights the significance of generalist and specialist fungal communities in mono and mixed myco‐type stands in modulating tree‐tree interaction, tree species co‐existence and regulating soil properties and ecosystem functions. Read the free Plain Language Summary for this article on the Journal blog.

Setting the stage for plant–soil feedback: Mycorrhizal influences over conspecific recruitment, plant and fungal communities, and coevolution

Abstract Plant–soil feedback (PSF) plays a central role in determining plant community dynamics, yet our understanding of how different combinations of plants and microbes influence PSF remains limited. Plants of different mycorrhizal types often exhibit contrasting PSF outcomes, influencing plant recruitment and spatial structure. Generalizing across plant species based on mycorrhizal type creates the potential to examine broader effects on ecological communities. We review mechanisms contributing to different PSF outcomes between arbuscular mycorrhizal and ectomycorrhizal trees. We focus on how plant and fungal traits that differ between mycorrhizal types interact with pathogenic and saprotrophic microorganisms and nutrient and carbon cycling. Synthesis. Building on this framework, we propose several new research directions. First, mycorrhizal‐induced changes in soils can operate beyond the conspecific level, spilling over from abundant plant species onto less abundant ones. This community‐level ‘mycorrhizal spillover’ is hypothesized to affect PSF in ways that are additive and interactive with conspecific density dependence. Second, we describe how mycorrhizal effects on PSF could structure the way plant communities respond to global change. Third, we discuss how they may influence plant evolution by altering the balance of selection pressures on traits and genes related to pathogen defence and mutualism formation.

Effects of long-term nitrogen addition on root nitrogen acquisition strategy: Insights from a 19-year experiment in two temperate tree species

Nitrogen (N) serves as the primary limiting nutrient for plant growth in the majority of terrestrial ecosystems. However, the effect of long-term N addition on root N acquisition, in particular the seasonal dynamics, is still not well understood. In a 19-year N addition experiment on plantations of ectomycorrhizal tree species Larix gmelinii (larch) and arbuscular mycorrhizal tree species Fraxinus mandshurica (ash), we determined root morphological, chemical and mycorrhizal traits, as well as soil properties. Concurrently, we used a field isotopic hydroponic method to measure root uptake rates of NH4+, NO3-, and glycine in the early, mid and late growing season. Following N addition, mycorrhizal colonization rates in both species were reduced in early and late growing season. Root tissue density was reduced but specific root length and area were increased in ash under N addition across growing seasons, however, no significant differences in these traits were found in larch. Under N addition, both species showed lower uptake rates of all N forms and the total N than the controls throughout the growing season, except for the glycine-uptake of larch in early growing season. N addition did not modify the N-uptake preference in both species, but the contributions of specific N form to the total N varied with seasons. Collectively, referring to the framework of “root economics space”, these two species particularly ash showed greater reliance on the “do-it-yourself” strategy for N acquisition under long-term N addition, although the degree of which somewhat varied with season. Seasonal dynamics in root N-uptake rates of ash were mainly related to soil temperature and moisture, rather than soil N properties, showing less direct impact of N addition. Our findings provide deep insights into the effect of N deposition on root N acquisition strategy and related functions of forest ecosystem.

Forest carbon stocks increase with higher dominance of ectomycorrhizal trees in high latitude forests

Understanding the mechanisms controlling forest carbon accumulation is crucial for predicting and mitigating future climate change. Yet, it remains unclear whether the dominance of ectomycorrhizal (EcM) trees influences the carbon accumulation of entire forests. In this study, we analyzed forest inventory data from over 4000 forest plots across Northeast China. We find that EcM tree dominance consistently exerts a positive effect on tree, soil, and forest carbon stocks. Moreover, we observe that these positive effects are more pronounced during unfavorable climate conditions, at lower tree species richness, and during early successional stages. This underscores the potential of increasing the dominance of native EcM tree species not only to enhance carbon stocks but also to bolster resilience against climate change in high-latitude forests. Here we show that forest managers can make informed decisions to optimize carbon accumulation by considering various factors such as mycorrhizal types, climate, successional stages, and species richness.

New Cortinariaceae species associated with Dicymbe, Aldina, and Pakaraimaea in Guyana

ABSTRACT Species of the ectomycorrhizal (ECM) family Cortinariaceae (Agaricales, Agaricomycetes, Basidiomycota) have long been considered impoverished or absent from lowland tropical rainforests. Several decades of collecting in forests dominated by ECM trees in South America’s Guiana Shield is countering this view, with discovery of numerous Cortinariaceae species. To date, ~12 morphospecies of this family have been found in the central Pakaraima Mountains of Guyana. Here, we describe three of these as new species of Cortinarius and two as new species of Phlegmacium from forests dominated by the ECM tree genera Dicymbe (Fabaceae subfam. Detarioideae), Aldina (Fabaceae subfam. Papilionoideae), and Pakaraimaea (Cistaceae). Macromorphological, micromorphological, habitat, and DNA sequence data are provided for each new species.

A common ericoid shrub modulates the diversity and structure of fungal communities across an arbuscular to ectomycorrhizal tree dominance gradient.

Differences between arbuscular (AM) and ectomycorrhizal (EcM) trees strongly influence forest ecosystem processes, in part through their impact on saprotrophic fungal communities. Ericoid mycorrhizal (ErM) shrubs likely also impact saprotrophic communities given that they can shape nutrient cycling by slowing decomposition rates and intensifying nitrogen limitation. We investigated the depth distributions of saprotrophic and EcM fungal communities in paired subplots with and without a common understory ErM shrub, mountain laurel (Kalmia latifolia L.), across an AM to EcM tree dominance gradient in a temperate forest by analyzing soils from the organic, upper mineral (0-10cm), and lower mineral (cumulative depth of 30cm) horizons. The presence of K. latifolia was strongly associated with the taxonomic and functional composition of saprotrophic and EcM communities. Saprotrophic richness was consistently lower in the Oa horizon when this ErM shrub species was present. However, in AM tree-dominated plots, the presence of the ErM shrub was associated with a higher relative abundance of saprotrophs. Given that EcM trees suppress both the diversity and relative abundance of saprotrophic communities, our results suggest that separate consideration of ErM shrubs and EcM trees may be necessary when assessing the impacts of plant mycorrhizal associations on belowground communities.

Mycorrhizal associations modify tree diversity-productivity relationships across experimental tree plantations.

Decades of studies have demonstrated links between biodiversity and ecosystem functioning, yet the generality of the relationships and the underlying mechanisms remain unclear, especially for forest ecosystems. Using 11 tree-diversity experiments, we tested tree species richness-community productivity relationships and the role of arbuscular (AM) or ectomycorrhizal (ECM) fungal-associated tree species in these relationships. Tree species richness had a positive effect on community productivity across experiments, modified by the diversity of tree mycorrhizal associations. In communities with both AM and ECM trees, species richness showed positive effects on community productivity, which could have resulted from complementarity between AM and ECM trees. Moreover, both AM and ECM trees were more productive in mixed communities with both AM and ECM trees than in communities assembled by their own mycorrhizal type of trees. In communities containing only ECM trees, species richness had a significant positive effect on productivity, whereas species richness did not show any significant effects on productivity in communities containing only AM trees. Our study provides novel explanations for variations in diversity-productivity relationships by suggesting that tree-mycorrhiza interactions can shape productivity in mixed-species forest ecosystems.

Factors associated with seedling establishment on logs of different fungal decay types-A seed-sowing experiment.

Wood decay fungi alter the abiotic and biotic properties of deadwood, which are important as nurse logs for seedling regeneration. However, the relationship between fungal decay type and seedling performance has not been evaluated experimentally. In this study, we examined the germination, growth, and survival of six arbuscular mycorrhizal (AM) and six ectomycorrhizal (ECM) tree species on three substrates (pine logs with brown and white rot and soil) by conducting seed-sowing experiments in a mixed forest dominated by Pinus densiflora and Quercus serrata. Analysis using ribosomal DNA internal transcribed spacer 1 (rDNA ITS1) sequencing revealed that the fungal community was significantly different across three substrates. The richness of operational taxonomic units (OTUs) of AM and ECM fungi was the largest on brown rot logs and soil, respectively. The substrate significantly affected the seedling performance when comparing wood decay types, but these were not consistent across the mycorrhizal status of the seedlings. Nevertheless, seedlings of some AM trees showed better growth and enhanced mycorrhizal colonization on brown rot logs than on white rot logs. The wood decay type influenced fungal communities in the logs and the performance of some seedling species partly by different mycorrhizal colonization rates. However, the effect was seedling species dependent and showed no apparent difference between AM and ECM trees.

Arbuscular and ectomycorrhizal tree seedling growth is inhibited by competition from neighboring roots and associated fungal hyphae

Arbuscular and ectomycorrhizal tree seedling growth is inhibited by competition from neighboring roots and associated fungal hyphae

Contrasting response of root traits of arbuscular mycorrhizal and ectomycorrhizal trees to phosphorus availability in subtropical forests

Contrasting response of root traits of arbuscular mycorrhizal and ectomycorrhizal trees to phosphorus availability in subtropical forests

Mixing of pine and arbuscular mycorrhizal tree species changed soil organic carbon storage by affecting soil microbial characteristics

Pure and mixed pine forests are found all over the world. The mycorrhizal type affects soil microbial activity and carbon sequestration capacity in pure forests. However, the effects of mycorrhizal type on microbial characteristics and carbon sequestration capacity in pine mixed forests remain untested. Further, making it difficult to predict carbon storage of the conversion from pure pine forests to mixed forests at larger scales. Herein, a meta-analysis showed that the contents of soil microbial biomass, mineral-associated organic carbon, and soil organic carbon in pine mixed forests with introduced arbuscular mycorrhizal tree species (PMAM) increased by 26.41 %, 58.55 %, and 27.41 %, respectively, compared to pure pine forests, whereas those of pine mixed forests without arbuscular mycorrhizal tree species (PMEcM) remained unchanged. Furthermore, the effect size of microbial biomass, mineral-associated organic carbon and organic carbon contents in subsoil of PMAM are 56.48 %, 78.49 % and 43.05 %, respectively, which are higher than those in topsoil. The improvement of carbon sinks throughout the PMAM soil profile is positively correlated with increases in microbial biomass and mineral-associated organic carbon in subsoil, according to regression analysis and structural equation modelling. In summary, these results highlight that the positive effects of introducing arbuscular mycorrhizal tree species rather than ectomycorrhizal tree species into pure pine forests on soil microbial biomass and carbon sequestration. The positive link between microbial biomass, mineral-associated organic carbon, and soil organic carbon suggests an underlying mechanism for how soil microorganisms store carbon in pine mixed forests. Nevertheless, our findings also imply that the soil carbon pool of PMAM may be vulnerable under climate change. Based on the above findings, we propose that incorporating mycorrhizal type of tree species and soil thickness into mixed forests management and biodiversity conservation.

Different phosphorus preferences among arbuscular and ectomycorrhizal trees in a subtropical forest

Phosphorus (P) is one of the most limiting elements for efficient plant growth and regeneration, coexisting plants are found to be able to partition soil P components through different types of mycorrhizal symbiosis. However, previous evidences were mostly based on artificial addition of different forms of P chemicals, there is still a lack of observational and experimental verifications on how tree species respond to soil P heterogeneity in natural soils. Herein, we conducted a field survey to investigate how spatial distribution of tree species with different types of mycorrhizal associations are related with soil P compositions. We found that arbuscular mycorrhizal (AM) trees tend to distribute in soils rich in inorganic P, while ectomycorrhizal (ECM) trees distribute in habitats with low inorganic P. We further established a shade-house experiment to evaluate how P availability of field soils affects seedling performance of AM and ECM trees. Biomass of AM seedlings was highest when grew in soil with the medium level of inorganic P, while ECM seedlings grown best in soil with the lowest inorganic P level. Seedling survival and mycorrhizal colonisation rates decreased, while specific root length and specific area of seedling roots increased, with increasing inorganic P concentrations. Using field soil with natural composition of P-forms and spatial heterogeneity, our findings confirmed the hypothesis that AM trees prefer inorganic P while ECM trees are able to utilise organic P in a more realistic setting, which regulated spatial distributions and promoted coexistence of subtropical tree species at local scale.

Influence of tree mycorrhizal type, tree species identity, and diversity on forest root-associated mycobiomes.

Understanding the complex interactions between trees and fungi is crucial for forest ecosystem management, yet the influence of tree mycorrhizal types, species identity, and diversity on tree-tree interactions and their root-associated fungal communities remains poorly understood. Our study addresses this gap by investigating root-associated fungal communities of different arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) tree species pairs (TSPs) in a subtropical tree diversity experiment, spanning monospecific, two-species, and multi-species mixtures, utilizing Illumina sequencing of the ITS2 region. The study reveals that tree mycorrhizal type significantly impacts the alpha diversity of root-associated fungi in monospecific stands. Meanwhile, tree species identity's influence is modulated by overall tree diversity. Tree-related variables and spatial distance emerged as major drivers of variations in fungal community composition. Notably, in multi-species mixtures, compositional differences between root fungal communities of AM and EcM trees diminish, indicating a convergence of fungal communities irrespective of mycorrhizal type. Interestingly, dual mycorrhizal fungal communities were observed in these multi-species mixtures. This research underscores the pivotal role of mycorrhizal partnerships and the interplay of biotic and abiotic factors in shaping root fungal communities, particularly in varied tree diversity settings, and its implications for effective forest management and biodiversity conservation.