Ectomycorrhizal Research Articles

Context-dependent benefits of forest soil addition on Aleppo pine seedling performance under drought and grass competition

Seedling establishment under natural conditions is limited by numerous interacting factors. Here, we tested the combined effects of drought, herbaceous competition, and ectomycorrhizal inoculation on the performance of Aleppo pine seedlings grown in a net-house. The roots of all pine seedlings were strongly dominated by Geopora, a fungal genus known to colonize seedlings in dry habitats. Ectomycorrhizal fungi (EMF) inoculum significantly increased seedling height, biomass, and the number of side branches. However, under either competition or drought, the positive effect of EMF on seedling biomass and height was greatly reduced, while the effect on shoot branching was maintained. Further, under a combination of drought and competition, EMF had no influence on either plant growth or shape. The discrepancy in pine performance across treatments highlights the complexity of benefits provided to seedlings by EMF under ecologically relevant settings.

Effects of small-scale outplanting fertilization on conifer seedling growth and fungal community establishment

Forestry in Sweden largely relies on planting genetically improved seedlings after clear-cutting, and high survival and early growth of planted seedlings is vital for stand establishment, economic viability, and carbon sequestration. Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) are the two most important tree species in Swedish forest stands and both are associated with a variety of ectomycorrhizal fungi. While seedlings are generally not fertilized at outplanting, previous results have shown that fertilization with arginine phosphate can increase root growth and seedling survival. However, it is not clear how this affects fungal community composition on the roots of growing seedlings. In a planting experiment sampled after one and two growing seasons, we found that planting position had the largest effects both on seedling performance and on fungal community composition and provide insight into the early stages of fungal community succession on planted Norway spruce and Scots pine seedlings. Fungal taxa present on seedlings before planting persisted on seedling roots, while some degree of novel colonization by site indigenous taxa was observed. Fertilization modified the relative abundance of some fungal taxa but did not lead to significant changes in overall community composition. In terms of seedling performance, ammonium nitrate led to increased mortality while arginine phosphate improved root growth.

Suillusgrevillei and Suillus luteus promote lead tolerance of Pinus tabulaeformis and biomineralize lead to pyromorphite.

Lead (Pb) is a hazardous heavy metal that accumulates in many environments. Phytoremediation of Pb polluted soil is an environmentally friendly method, and a better understanding of mycorrhizal symbiosis under Pb stress can promote its efficiency and application. This study aims to evaluate the impact of two ectomycorrhizal fungi (Suillus grevillei and Suillus luteus) on the performance of Pinus tabulaeformis under Pb stress, and the biomineralization of metallic Pb in vitro. A pot experiment using substrate with 0 and 1,000 mg/kg Pb2+ was conducted to evaluate the growth, photosynthetic pigments, oxidative damage, and Pb accumulation of P. tabulaeformis with or without ectomycorrhizal fungi. In vitro co-cultivation of ectomycorrhizal fungi and Pb shots was used to evaluate Pb biomineralization. The results showed that colonization by the two ectomycorrhizal fungi promoted plant growth, increased the content of photosynthetic pigments, reduced oxidative damage, and caused massive accumulation of Pb in plant roots. The structural characteristics of the Pb secondary minerals formed in the presence of fungi demonstrated significant differences from the minerals formed in the control plates and these minerals were identified as pyromorphite (Pb5(PO4)3Cl). Ectomycorrhizal fungi promoted the performance of P. tabulaeformis under Pb stress and suggested a potential role of mycorrhizal symbiosis in Pb phytoremediation. This observation also represents the first discovery of such Pb biomineralization induced by ectomycorrhizal fungi. Ectomycorrhizal fungi induced Pb biomineralization is also relevant to the phytostabilization and new approaches in the bioremediation of polluted environments.

Ectomycorrhizal fungi alter soil food webs and the functional potential of bacterial communities.

Most of Earth's trees rely on critical soil nutrients that ectomycorrhizal fungi (EcMF) liberate and provide, and all of Earth's land plants associate with bacteria that help them survive in nature. Yet, our understanding of how the presence of EcMF modifies soil bacterial communities, soil food webs, and root chemistry requires direct experimental evidence to comprehend the effects that EcMF may generate in the belowground plant microbiome. To this end, we grew Pinus muricata plants in soils that were either inoculated with EcMF and native forest bacterial communities or only native bacterial communities. We then profiled the soil bacterial communities, applied metabolomics and lipidomics, and linked omics data sets to understand how the presence of EcMF modifies belowground biogeochemistry, bacterial community structure, and their functional potential. We found that the presence of EcMF (i) enriches soil bacteria linked to enhanced plant growth in nature, (ii) alters the quantity and composition of lipid and non-lipid soil metabolites, and (iii) modifies plant root chemistry toward pathogen suppression, enzymatic conservation, and reactive oxygen species scavenging. Using this multi-omic approach, we therefore show that this widespread fungal symbiosis may be a common factor for structuring soil food webs.IMPORTANCEUnderstanding how soil microbes interact with one another and their host plant will help us combat the negative effects that climate change has on terrestrial ecosystems. Unfortunately, we lack a clear understanding of how the presence of ectomycorrhizal fungi (EcMF)-one of the most dominant soil microbial groups on Earth-shapes belowground organic resources and the composition of bacterial communities. To address this knowledge gap, we profiled lipid and non-lipid metabolites in soils and plant roots, characterized soil bacterial communities, and compared soils amended either with or without EcMF. Our results show that the presence of EcMF changes soil organic resource availability, impacts the proliferation of different bacterial communities (in terms of both type and potential function), and primes plant root chemistry for pathogen suppression and energy conservation. Our findings therefore provide much-needed insight into how two of the most dominant soil microbial groups interact with one another and with their host plant.

Characterization of ectomycorrhizal fungal community of Abies Pindrow using sporocarp sampling, morphotyping, and metabarcoding through next-generation sequencing.

Abies pindrow, commonly known as the West-Himalayan Fir, holds great ecological importance as a native tree species in the Himalayas. Beyond its value as a fuel and timber source, it serves as a keystone species within the ecosystem. However, over recent years, extensive degradation and deforestation have afflicted A. pindrow forests. Utilizing ectomycorrhizal fungal symbionts of A. pindrow could prove pivotal in restoring these deteriorated forests. This study aimed to evaluate the diversity and composition of the ectomycorrhizal fungal community associated with A. pindrow. We employed ectomycorrhizal root tip morphotyping, sporocarp sampling, and Illumina MiSeq metabarcoding of the ITS region of fungal nrDNA. The ectomycorrhizal root tips were categorized into 10 morphotypes based on their morphological characteristics, exhibiting an average colonization rate of 74%. Sporocarp sampling revealed 22 species across 10 genera, with Russula being the most prevalent. The metabarcoding yielded 285,148 raw sequences, identifying 326 operational taxonomic units (OTUs) belonging to 193 genera, 114 families, 45 orders, 22 classes, and 6 divisions. Of these, 36 OTUs across 20 genera were ectomycorrhizal, constituting 63.1% of the fungal community. Notably, Tuber was the most abundant, representing 37.42% of the fungal population, followed by Russula at 21.06%. This study provides a comprehensive understanding of mycorrhizal symbionts of A. pindrow. The findings hold significant implications for utilizing dominant ectomycorrhizal fungi in reforestation endeavors aimed at restoring this important Himalayan conifer.

Soil mycobiomes in native European aspen forests and hybrid aspen plantations have a similar fungal richness but different compositions, mainly driven by edaphic and floristic factors.

The cultivation of short-rotation tree species on non-forest land is increasing due to the growing demand for woody biomass for the future bioeconomy and to mitigate climate change impacts. However, forest plantations are often seen as a trade-off between climate benefits and low biodiversity. The diversity and composition of soil fungal biota in plantations of hybrid aspen, one of the most planted tree species for short-rotation forestry in Northern Europe, are poorly studied. The goal of this study was to obtain baseline knowledge about the soil fungal biota and the edaphic, floristic and management factors that drive fungal richness and communities in 18-year-old hybrid aspen plantations on former agricultural soils and compare the fungal biota with those of European aspen stands on native forest land in a 130-year chronosequence. Sites were categorized as hybrid aspen (17-18-year-old plantations) and native aspen stands of three age classes (8-29, 30-55, and 65-131-year-old stands). High-throughput sequencing was applied to soil samples to investigate fungal diversity and assemblages. Native aspen forests showed a higher ectomycorrhizal (EcM) fungal OTU richness than plantations, regardless of forest age. Short-distance type EcM genera dominated in both plantations and forests. The richness of saprotrophic fungi was similar between native forest and plantation sites and was highest in the middle-aged class (30-55-year-old stands) in the native aspen stands. The fungal communities of native forests and plantations were significantly different. Community composition varied more, and the natural forest sites were more diverse than the relatively homogeneous plantations. Soil pH was the best explanatory variable to describe soil fungal communities in hybrid aspen stands. Soil fungal community composition did not show any clear patterns between the age classes of native aspen stands. We conclude that edaphic factors are more important in describing fungal communities in both native aspen forest sites and hybrid aspen plantation sites than forest thinning, age, or former land use for plantations. Although first-generation hybrid aspen plantations and native forests are similar in overall fungal diversity, their taxonomic and functional composition is strikingly different. Therefore, hybrid aspen plantations can be used to reduce felling pressure on native forests; however, our knowledge is still insufficient to conclude that plantations could replace native aspen forests from the soil biodiversity perspective.

Effects of Black and White Mulch on Mycelial Growth of Tuber Species in Korean Field Environment

Truffles, belonging to the genus Tuber, are ectomycorrhizal (ECM) fungi that form underground ascocarps and primarily establish symbiosis with oaks and hazels. The cultivation of Tuber spp. involves transplanting inoculated seedlings that have formed ectomycorrhiza with Tuber species, with mulching being effective for truffle cultivation. In this study, we investigated the effects of mulching on the mycelial growth of four Tuber species (T. himalayense, T. koreanum, T. melanosporum, and T. borchii) in the Korean natural environment, highlighting the potential for Korea as a truffle cultivation site. We developed and tested species-specific primers for quantifying the soil mycelial biomass of Tuber spp. by qRT-PCR, determined the superior mulch color for mycelial growth, and identified the Tuber species exhibiting the highest growth rate in the Korean field environment. Our results demonstrated that white mulch significantly enhanced mycelial growth in Tuber species than black mulch, likely owing to its ability to maintain low soil temperatures, control weeds, and improve host plant growth. Among the Tuber species, T. himalayense showed the greatest growth potential in the Korean natural environment. Additionally, a significant and positive correlation was observed between the mycelial biomass of Tuber species and the growth of inoculated seedlings, as measured by the total stem length and the number of leaves, thereby indicating the importance of symbiosis between ECM fungi and host plants. This study provides valuable insights into truffle cultivation in Korea and highlights the potential of using white mulch to promote mycelial growth, thereby contributing essential data for understanding the appropriate environmental conditions for Tuber spp. cultivation in Korea. Further study is needed to assess the long-term impact of mulching and to explore the effectiveness of other mulching materials.

"Ectomycorrhizal exploration type" could be a functional trait explaining the spatial distribution of tree symbiotic fungi as a function of forest humus forms.

In European forests, most tree species form symbioses with ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) fungi. The EM fungi are classified into different morphological types based on the development and structure of their extraradical mycelium. These structures could be root extensions that help trees to acquire nutrients. However, the relationship between these morphological traits and functions involved in soil nutrient foraging is still under debate.We described the composition of mycorrhizal fungal communities under 23 tree species in a wide range of climates and humus forms in Europe and investigated the exploratory types of EM fungi. We assessed the response of this tree extended phenotype to humus forms, as an indicator of the functioning and quality of forest soils. We found a significant relationship between the relative proportion of the two broad categories of EM exploration types (short- or long-distance) and the humus form, showing a greater proportion of long-distance types in the least dynamic soils. As past land-use and host tree species are significant factors structuring fungal communities, we showed this relationship was modulated by host trait (gymnosperms versus angiosperms), soil depth and past land use (farmland or forest).We propose that this potential functional trait of EM fungi be used in future studies to improve predictive models of forest soil functioning and tree adaptation to environmental nutrient conditions.

Trophic facilitation in forest restoration: Can Nothofagus trees use ectomycorrhizal fungi of the pioneer shrub Leptospermum?

The benefits of plant-to-plant facilitation in ecological restoration are well recognized, yet the potential for indirect trophic facilitation remains understudied. Nothofagus (southern beech; Nothofagaceae) is an iconic southern hemisphere tree genus that is frequently the focus of ecological restoration efforts. One aspect of Nothofagus ecology that may limit restoration success is the availability of appropriate ectomycorrhizal fungi. It has been suggested that pioneer dual-mycorrhizal hosts such as Leptospermum species (Myrtaceae) could facilitate Nothofagus establishment by providing fungal inoculum, but the capacity for Nothofagus to use Leptospermum ectomycorrhizal fungi is unknown. To investigate potential indirect facilitation, we conducted a common garden pot trial to determine if Nothofagus cliffortioides (mountain beech) can use symbionts from Leptospermum scoparium (mānuka) ectomycorrhizal communities. Nothofagus and Leptospermum seedlings were grown in monoculture and mixed pairs with reciprocal "home" and "away" soil fungal inoculum. ITS2 metabarcoding of eDNA from hyphal ingrowth bags revealed that Nothofagus and Leptospermum inoculum contained different ectomycorrhizal fungal communities, but that half of the common ectomycorrhizal taxa identified were found in both soil types, suggesting generalist fungi exist. Nothofagus was able to form associations with some fungal species originating from Leptospermum inoculum, however, probable spore contamination meant that the proportion of root colonization associated with those species was ambiguous. Root ectomycorrhizal colonization rates were positively associated with seedling biomass, and there was some evidence of a home soil inoculum advantage in Nothofagus, but these effects were minor. Additionally, we found evidence that home inoculum provides a protective advantage against drought stress for Leptospermum seedlings. Our results indicate the potential for using Leptospermum to promote Nothofagus establishment in restoration plantings and highlight the possible benefits of considering fungal mutualists in ecological restoration projects.

Century-long recovery of mycorrhizal interactions in European beech forests after mining

Abstract Background and aims Ecological restoration strategies are emerging globally to counteract biodiversity loss and ecosystem degradation. However, restored ecosystems may not reach undisturbed biodiversity and functionality. One reason of this limited success may be a focus on short-term recovery of diversity, composition, or isolated functions. These simplified metrics may underestimate the real time ecosystems need to recover. Thus, studies of more complex metrics, like biotic interactions, at larger timescales, are essential to understand ecosystem recovery. Methods Using molecular identification, we assessed the recovery of the interactions between ectomycorrhizal (EcM) fungi and European beech (Fagus sylvatica L.) in two opencast iron mines in use since the fourteenth century and abandoned over 107 and 148 years. Results Species richness, species diversity, Basidiomycota/Ascomycota abundance ratio and taxonomic distinctness of EcM fungi recovered to undisturbed values, whereas species composition was still different. Certain fungal functional traits (i.e. exploration and sporocarp types) also reached undisturbed values. Differences in soil pH and NH4+ affected the composition of the EcM communities associated with beech, suggesting that mining caused a long-term impact in soil biogeochemistry, that directly impacted beech-EcM interactions. Conclusion Mycorrhizal interactions require more than 150 years to recover following mining. Contrary to the rapid recovery response provided by simple metrics like species richness, recovery metrics with more ecological information, like the identity of plant-EcM interactions, may be still capturing signals of incomplete recovery.

Mycoheterotrophy in the wood-wide web.

The prevalence and potential functions of common mycorrhizal networks, or the 'wood-wide web', resulting from the simultaneous interaction of mycorrhizal fungi and roots of different neighbouring plants have been increasingly capturing the interest of science and society, sometimes leading to hyperbole and misinterpretation. Several recent reviews conclude that popular claims regarding the widespread nature of these networks in forests and their role in the transfer of resources and information between plants lack evidence. Here we argue that mycoheterotrophic plants associated with ectomycorrhizal or arbuscular mycorrhizal fungi require resource transfer through common mycorrhizal networks and thus are natural evidence for the occurrence and function of these networks, offering a largely overlooked window into this methodologically challenging underground phenomenon. The wide evolutionary and geographic distribution of mycoheterotrophs and their interactions with a broad phylogenetic range of mycorrhizal fungi indicate that common mycorrhizal networks are prevalent, particularly in forests, and result in net carbon transfer among diverse plants through shared mycorrhizal fungi. On the basis of the available scientific evidence, we propose a continuum of carbon transfer options within common mycorrhizal networks, and we discuss how knowledge on the biology of mycoheterotrophic plants can be instrumental for the study of mycorrhizal-mediated transfers between plants.

Interactions between root and rhizosphere microbes mediate phosphorus acquisition in Pinus tabulaeformis

The Pinus tabulaeformis plantation is a major industrial forest in China. Phosphorus (P) deficiency seriously affected its growth and productivity. Root traits and rhizosphere microorganisms play essential roles in plant P acquisition. However, how root traits interact with microbial communities for P acquisition remains largely unclear. The responses of P. tabulaeformis root morphological characteristics, oxalic acid, soil P fractions and rhizosphere bacterial and fungal communities and potential functions to P addition were investigated using a pot experiment with three P levels (0, 20, and 80 mg P kg−1 soil). Additionally, we constructed a functional synthetic microbial community (SynCom) and verified their behaviors in promoting plant P acquisition and growth. P fertilization significantly increased the soil CaCl2-P, citrate-P, HCl-P and microbial biomass P (MBP) fractions and decreased oxalic acid, bacterial indicator genera in P deficiency and ectomycorrhizal fungi (ECM). Most of the bacterial indicator genera in P deficiency were negatively correlated with citrate-P and HCl-P but were positively correlated with alkaline phosphatase (ALP) and oxalic acid. According to structure equation models, soil total P could directly influence P acquisition efficiency and indirectly through its effects on ECM or by regulating oxalic acid, which regulated bacterial indicator genera in P deficiency and thus affected ALP production. Inoculation with SynCom significantly increased soil available P contents, ALP activities, root P concentrations and superoxide dismutase activities. Under low P conditions, P. tabulaeformis adopted a high carbon cost strategy for P acquisition, specifically moderating root secretion. Rhizosphere bacteria could accelerate soil P mobility and enhance the P absorption ability and systemic resistance of roots to alleviate P stress. This study provided the theoretical basis for the exploitation and utilization of microbial fertilizers, as well as for the cultivation and management of plantation.

Three helmet-orchid species share abundant fungi of Serendipitaceae regardless of altitude

The tiny terrestrial orchids (plant height less than 8 cm) in the genus Corybas dependent on mycorrhizal fungal (OMF) partners for seed germination and seedling development. The OMF community of the Corybas remains poorly understood, although the relevant knowledge is very important for in situ and ex situ conservation of these orchids. In this study, we characterized OMF richness and compositions of three helmet-orchid species, i.e., Corybas geminigibbus, C. himalaicus, and C. shanlinshiensis, from their natural habitats by using Illumina sequencing of the internal transcribed spacer 2 region. We found that fungal colonization was restricted in the rhizomes of the helmet-orchids instead of their tuberoids, and serendipitoid fungi were predominant, while tulasnelloid were absent in the three investigated Corybas species regardless of their altitude. The three Corybas species shared 27 serendipitoid operational taxonomic units that are different to those of their related orchids, the genera of Cyrtostylis and Stigmatodactylus. Corybas shanlinshiensis alone had a range of ectomycorrhizal fungi (mainly russuloid and thelephoroid) broader than C. himalaicus and C. geminigibbus. Our study provides new information about terrestrial orchid–fungi associations and may further contribute to orchid 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.

Molecular characterization of the complete genome of a novel ormycovirus infecting the ectomycorrhizal fungus Hortiboletus rubellus.

Advancements in high-throughput sequencing and the development of new bioinformatics tools for large-scale data analysis play a crucial role in uncovering virus diversity and enhancing our understanding of virus evolution. The discovery of the ormycovirus clades, a group of RNA viruses that are phylogenetically distinct from all known Riboviria members and are found in fungi, highlights the value of these tools for the discovery of novel viruses. The aim of this study was to examine viral populations in fungal hosts to gain insights into the diversity, evolution, and classification of these viruses. Here, we report the molecular characterization of a newly discovered ormycovirus, which we have named "Hortiboletus rubellus ormycovirus 1" (HrOMV1), that was found in the ectomycorrhizal fungus Hortiboletus rubellus. The bipartite genome of HrOMV1, whose nucleotide sequence was determined by HTS and RLM-RACE, consists of two RNA segments (RNA1 and RNA2) that exhibit similarity to those of previously studied ormycoviruses in their organization and the proteins they encode. The presence of upstream, in-frame AUG triplets in the 5' termini of both RNA segments suggests that HrOMV1, like certain other ormycoviruses, employs a non-canonical translation initiation strategy. Phylogenetic analysis showed that HrOMV1 is positioned within the gammaormycovirus clade. Its putative RNA-dependent RNA polymerase (RdRp) exhibits sequence similarity to those of other gammaormycovirus members, the most similarity to that of Termitomyces ormycovirus 1, with 33.05% sequence identity. This protein was found to contain conserved motifs that are crucial for RNA replication, including the distinctive GDQ catalytic triad observed in gammaormycovirus RdRps. The results of this study underscore the significance of investigating the ecological role of mycoviruses in mycorrhizal fungi. This is the first report of an ormycovirus infecting a member of the ectomycorrhizal genus Hortiboletus.

Age-Related Conservation in Plant-Soil Feedback Accompanied by Ectomycorrhizal Domination in Temperate Forests in Northeast China.

This study investigates the effects of forest aging on ectomycorrhizal (EcM) fungal community and foraging behavior and their interactions with plant-soil attributes. We explored EcM fungal communities and hyphal exploration types via rDNA sequencing and investigated their associations with plant-soil traits by comparing younger (~120 years) and older (~250 years) temperate forest stands in Northeast China. The results revealed increases in the EcM fungal richness and abundance with forest aging, paralleled by plant-soil feedback shifting from explorative to conservative nutrient use strategies. In the younger stands, Tomentella species were prevalent and showed positive correlations with nutrient availability in both the soil and leaves, alongside rapid increases in woody productivity. However, the older stands were marked by the dominance of the genera Inocybe, Hymenogaster, and Otidea which were significantly and positively correlated with soil nutrient contents and plant structural attributes such as the community-weighted mean height and standing biomass. Notably, the ratios of longer-to-shorter distance EcM fungal exploration types tended to decrease along with forest aging. Our findings underscore the integral role of EcM fungi in the aging processes of temperate forests, highlighting the EcM symbiont-mediated mechanisms adapting to nutrient scarcity and promoting sustainability in plant-soil consortia.

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.

Response of Soil Fungal-Community Structure to Crop-Tree Thinning in Pinus massoniana Plantation

To address the ecological challenges arising from pure forest plantations and the wood supply–demand imbalance, implementing sustainable forest management is paramount. Accordingly, we studied crop trees at three densities (100, 150, and 200 N/ha) in a subtropical Pinus massoniana plantation. Our study revealed that the dominant phyla and genera within the fungal community remained largely consistent, with Basidiomycota and Ascomycota occupying prominent positions. Notably, the β diversity of the fungal community exhibited significant changes. Ectomycorrhizal and saprophytic fungi emerged as crucial functional guilds, and crop-tree thinning contributed to increased complexity within the fungal network, with a prevalence of positive rather than negative correlations among genera. The significant roles played by Camphor plants and ferns were evident in the fungal networks. Additionally, under crop-tree thinning, plant diversity experienced a significant boost, fostering interactions with the fungal community. Herb diversity played a vital role in the fungal community, affecting it either directly or indirectly, by altering the content of total phosphorus or organic matter in the soil. This study underscores the relationship between undergrowth plants and soil fungal communities, offering a scientific basis for evaluating the sustainability of restoring inefficient forest-plantation ecosystems.

Mixed-Species Stands Improve the Coordination between Leaf and Fine Root Traits in a Common Garden Experiment

The coordination between leaf and root traits is conducive to an integrated understanding of whole-plant ecological strategies and reveals how community composition and diversity contribute to defining the functions and services of ecosystems. However, there is limited understanding regarding the impact of species richness and trait categories on the coordination between leaf and root traits. Based on a 9-year common garden experiment, we investigated the leaf and fine root traits of 56 plots (25.8 m × 25.8 m) encompassing various trait categories (trait categories were defined according to the root depth, leaf habit, and mycorrhizal type) and different levels of species richness (1, 2, 4, 8) in the context of a forest biodiversity and ecosystem functioning experiment conducted in subtropical China (BEF-China). We found the following: (1) Our findings indicate that there was generally a significant difference in leaf traits, occasionally in absorptive root traits, and no difference in transport root traits between different trait categories. (2) Conversely, species richness significantly influenced all transport root traits except root nitrogen and most leaf and absorptive root traits. (3) The results demonstrated that trait categories played a crucial role in the coordination between leaf and fine root traits. Additionally, the coordination between leaf and fine root traits increased with higher species richness, particularly in deep-rooted, evergreen, and ectomycorrhizal fungi species. Furthermore, the coordination between leaf and fine root traits was significantly lower in monocultures compared to four- and eight-species mixtures. These results suggest that a significant mixture effect exists in the coordination between leaf and fine root traits due to the comprehensive and divergent capture of above- and belowground resources and reduced intraspecific competition. Therefore, compared to monocultures, mixed-species stands can enhance the coordination of leaf and fine root traits, and it is advisable to establish forests with mixtures of more than four species, dominated by deep-rooted, evergreen, and ectomycorrhizal fungi species, to maintain ecosystem stability and functional integrity.

Ectomycorrhizal Diversity and Exploration Types in Salix caprea

The tree species Salix caprea shows high adaptability to different habitat conditions and is economically valuable as a woody crop for biomass production. Moreover, S. caprea is dependent on mycorrhizal fungi, which are crucial for its growth and adaptability in different environments. Hence, this study explores the ectomycorrhizal diversity of S. caprea by utilizing the taxonomy (morphotyping and a molecular approach using the ITS and LSU regions) and trait diversity (exploration types) at two test sites in Germany and Poland. In total, 19 ectomycorrhizal (EM) morphotypes of S. caprea were characterized. Seven taxa were identified at the species level (Hebeloma populinum, Cortinarius atrocoerulaeus, Inocybe hirtella, Laccaria cf. ochropurpurea, Tuber maculatum, Cenococcum geophilum, and Phialophora finlandia) and twelve at the genus level (Tomentella spp. 1–8, Hebeloma sp. 1, Inocybe sp. 1, and Tuber spp. 1–2). The EM colonization ranged from 14 to 28% of the fine root tips. At both test sites, the largest portion of the total EM colonization consisted of Thelephoraceae. The exploration types were classified as medium-distance smooth (Tomentella sp. 1–8 and L. ochropurpurea) and medium-distance fringe (C. atrocoerulaeus), while the other taxa were short-distance exploration types, highlighting their potential functional role in the adaptation and growth of S. caprea.