Changes in ectomycorrhizal community structure on two containerized oak hosts across an experimental hydrologic gradient

Shifts in ectomycorrhizal (ECM) community structure were examined across an experimental hydrologic gradient on containerized seedlings of two oak species, Quercus montana and Quercus palustris, inoculated from a homogenate of roots from mature oak trees. At the end of one growing season, seedlings were harvested, roots were sorted by morphotype, and proportional colonization of each type was determined. DNA was subsequently extracted from individual root tips for polymerase chain reaction, restriction fragment length polymorphism, and rDNA sequencing of the ITS1/5.8S/ITS2 region to determine identities of fungal morphotypes. Twelve distinct molecular types were identified. Analysis of similarity showed that ECM fungal assemblages shifted significantly in composition across the soil moisture gradient. Taxa within the genus Tuber and the family Thelephoraceae were largely responsible for the changes in fungal assemblages. There were also significant differences in ECM community assemblages between the two oak host species. These results demonstrate that the structure of ECM fungal communities depends on both the abiotic and biotic environments and can shift with changes in soil moisture as well as host plant, even within the same genus.     

Plant host and soil origin influence fungal and bacterial assemblages in the roots of woody plants

Microbial communities in plant roots provide critical links between above‐ and belowground processes in terrestrial ecosystems. Variation in root communities has been attributed to plant host effects and microbial host preferences, as well as to factors pertaining to soil conditions, microbial biogeography and the presence of viable microbial propagules. To address hypotheses regarding the influence of plant host and soil biogeography on root fungal and bacterial communities, we designed a trap‐plant bioassay experiment. Replicate Populus, Quercus and Pinus plants were grown in three soils originating from alternate field sites. Fungal and bacterial community profiles in the root of each replicate were assessed through multiplex 454 amplicon sequencing of four loci (i.e., 16S, SSU, ITS, LSU rDNA). Soil origin had a larger effect on fungal community composition than did host species, but the opposite was true for bacterial communities. Populus hosted the highest diversity of rhizospheric fungi and bacteria. Root communities on Quercus and Pinus were more similar to each other than to Populus. Overall, fungal root symbionts appear to be more constrained by dispersal and biogeography than by host availability.     

Diversity and host preference of fungi co-inhabiting Cenococcum mycorrhizae

Diverse fungal assemblages colonize the fine feeder roots of woody plants, including mycorrhizal fungi, fungal root endophytes and soil saprotrophs. The fungi co-inhabiting Cenococcum geophilum ectomycorrhizae (ECM) of Abies balsamea, Betula papyrifera and Picea glauca were studied at two boreal forest sites in Eastern Canada by direct PCR of ITS rDNA. 50 non-Cenococcum fungal sequence types were detected, including several potentially mycorrhizal species as well as fungal root endophytes. Non-melanized ascomycetes dominated, in contrast to the dark septate endophytes (DSE) reported in most culture dependent studies. The results demonstrate significant differences in root associated fungal assemblages among the host species studied. Fungal diversity was also host dependent, with P. glauca roots supporting a more diverse community than A. balsamea. Differences in root associated fungal communities may well influence ecological interactions among host plant species.     

Strong host preference of ectomycorrhizal fungi in a Tasmanian wet sclerophyll forest as revealed by DNA barcoding and taxon-specific primers

Ectomycorrhizal (ECM) symbiosis is a widespread plant nutrition strategy in Australia, especially in semiarid regions. This study aims to determine the diversity, community structure and host preference of ECM fungi in a Tasmanian wet sclerophyll forest. Ectomycorrhizal fungi were identified based on anatomotyping and rDNA internal transcribed spacer (ITS)-large subunit (LSU) sequence analysis using taxon-specific primers. Host tree roots were identified based on root morphology and length differences of the chloroplast trnL region. A total of 123 species of ECM fungi were recovered from root tips of Eucalyptus regnans (Myrtaceae), Pomaderris apetala (Rhamnaceae) and Nothofagus cunninghamii (Nothofagaceae). The frequency of two thirds of the most common ECM fungi from several lineages was significantly influenced by host species. The lineages of Cortinarius, Tomentella-Thelephora, Russula-Lactarius, Clavulina, Descolea and Laccaria prevailed in the total community and their species richness and relative abundance did not differ by host species. This study demonstrates that strongly host-preferring, though not directly specific, ECM fungi may dominate the below-ground community. Apart from the richness of Descolea, Tulasnella and Helotiales and the lack of Suillus-Rhizopogon and Amphinema-Tylospora, the ECM fungal diversity and phylogenetic community structure is similar to that in the Holarctic realm.     

Ectomycorrhizal fungal community structure across a bog-forest ecotone in southeastern Alaska

We examined the ectomycorrhizal (ECM) fungal community across a bog-forest ecotone in southeastern Alaska. The bog and edge were both characterized by poorly drained Histosols and a continuous layer of Sphagnum species, ericaceous shrubs, Carex species, and shore pine [Pinus contorta Dougl. ex Loud. var. contorta]. The forest had better-drained Inceptisols and Spodosols, a tree community comprised of western hemlock [Tsuga heterophylla (Raf.) Sarg.], yellow cedar (Thuja plicata Donn ex D. Don.), Sitka spruce [Picea sitchensis (Bong.) Carr.] and shore pine, and an understorey of ericaceous shrubs and herbs. ECM root tip density (tips cm^–3 soil) was significantly greater in the forest than the edge or bog and ECM colonization was significantly different in all three plant communities. The below ground ECM fungal taxa were analyzed using molecular techniques (PCR-RFLP and DNA sequencing). Three ECM fungal taxa, Suillus tomentosus (Kauffman) Singer, Cenococcum geophilum Fr.:Fr, and a Russula species, differed in relative frequency, yet were among the four most frequent in all three plant communities. Although differences in ECM fungal richness were observed across plant communities, unequal sampling of ECM roots due to root density and colonization differences confounded richness comparisons. Using resampling procedures for creating taxon-accumulation curves as a function of sampled ECM roots revealed similarities in cumulative ECM fungal taxa richness across the ecotone.     

川西不同树种人工林对土壤涵水能力的影响

为评价青藏高原东缘不同树种造林对土壤涵水能力的影响,选择立地条件与营林方式相同的4种人工林(连香树(Cercidiphyllum japonicum)、油松(Pinus tabulaeformis)、落叶松(Larix kaempferi)和华山松(Pinus armandii))为研究对象,以落叶阔叶灌丛为对照,比较造林恢复28 a后不同人工林土壤孔隙度及持水性的变化,结合林地凋落物贮量及细根生物量等参数,试图揭示造成不同人工林地土壤涵水能力及潜力差异化的因素。结果显示:营造油松和华山松纯林不仅没能有效改善土壤孔隙状况,反而加剧了土壤涵水功能的退化。相反,连香树和落叶松在代替次生落叶灌丛造林后,土壤容重显著下降,孔隙度增加且小孔隙比例升高,持蓄水能力提高。凋落物及细根特性是不同林地土壤持水性能差异的重要因素。综合分析表明,在对退化生态系统进行造林恢复时,应尽量避免营造高密度针叶纯林,应结合种植有助于土壤结构改良的落叶或阔叶树种。     

Genetic host-tree effects on the ectomycorrhizal community and root characteristics of Norway spruce

A greenhouse experiment was used to study the effects of host genotype on short root formation and ectomycorrhizal (ECM) fungal community structure in Norway spruce (Picea abies (L.) Karst.). Rooted cuttings representing 55 clones were inoculated with a mix of vegetative hyphae of five ECM fungal species (Laccaria sp., Amphinema byssoides, Piloderma sp., Cadophora finlandia, Paxillus involutus). After one growing season, the ECM fungal community structure was determined by amplifying the fungal internal transcribed spacer (ITS) of ribosomal DNA directly from ECM root tips. Restriction profiles of obtained amplicons were then compared to those of the inoculated strains. Spruce clones differed in their ECM fungal community composition; we found a statistically significant clone-specific effect on ECM fungal diversity and dominating fungal species. Nevertheless, the broad sense heritabilities of the levels of Laccaria sp., Piloderma sp. and A. byssoides colonisations as well as the ECM fungal community structure were low (H ²?=?0.04?0.11), owing to the high within-clone variation. As nitrogen concentration of needles correlated negatively with ECM fungal richness, our results imply that in the experimental conditions nutrient acquisition of young trees may benefit from colonisation with only one or two ECM fungal species. The heritability of short root density was moderate (H ²?=?0.41) and highest among all the measured shoot and root growth characteristics of Norway spruce cuttings. We suggest that the genetic component determining root growth and short root formation is significant for the performance of young trees in natural environments as these traits drive the formation of the below-ground symbiotic interactions.     

Spatial structure and the effects of host and soil environments on communities of ectomycorrhizal fungi in wooded savannas and rain forests of Continental Africa and Madagascar

Mycorrhizal fungi play a key role in mineral nutrition of terrestrial plants, but the factors affecting natural distribution, diversity and community composition of particularly tropical fungi remain poorly understood. This study addresses shifts in community structure and species frequency of ectomycorrhizal (EcM) fungi in relation to host taxa, soil depth and spatial structure in four contrasting African ecosystems. We used the rDNA and plastid trnL intron sequence analysis for identification of fungi and host plants, respectively. By partitioning out spatial autocorrelation in plant and fungal distribution, we suggest that African EcM fungal communities are little structured by soil horizon and host at the plant species and family levels. These findings contrast with patterns of vegetation in these forests and EcM fungal communities in other tropical and temperate ecosystems. The low level of host preference indirectly supports an earlier hypothesis that pioneer Phyllanthaceae may facilitate the establishment of late successional Fabaceae and potentially other EcM host trees by providing compatible fungal inoculum in deforested and naturally disturbed ecosystems of tropical Africa.     

Effects of liming on ectomycorrhizal community structure in relation to soil horizons and tree hosts

Liming is a forestry practice used to correct tree cation deficiency induced by soil acidity. Ectomycorrhizal (ECM) community structure and functioning is closely linked to soil nutrient availability, which is strongly affected by liming. The aim of this study was to assess the impact of liming on ECM community structure depending on soil horizon and tree host. Acidophilic species occurring in untreated plots, such as Russula ochroleuca, were absent from limed plots and were replaced by more generalist morphtoypes. The abundance of ECM root tips in the untreated plots was higher in topsoil layers, whereas most of the ECM root tips in the limed plots were in the organomineral layer, whatever the tree host. Liming was the major determinant of fungal community structure, then tree host.     

Mycorrhizal associations in woody plant species at the Mt. Usu volcano,Japan

We investigated the association between ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi and pioneer woody plant species in areas devastated by the eruption of Mt. Usu, Japan, in 2000. We observed eight woody plant species at the research site, most of which were associated with ECM and/or AM fungi. In particular, dominant woody plant species Populus maximowiczii, Salix hultenii var. angustifolia and Salix sachalinensis were consistently associated with ECM fungi and erratically associated with AM fungi. We found one to six morphotypes in the roots of each ECM host and, on average, two in the roots of each seedling, indicating low ECM fungal diversity. ECM colonization ranged from 17 to 42% of root tips. Using morphotyping and molecular analyses, 15 ECM fungi were identified. ECM fungi differed greatly between hosts. However, Laccaria amethystea, Hebeloma mesophaeum, Thelephora terrestris and other Thelephoraceae had high relative colonization, constituting the majority of the ECM colonization in the roots of each plant species. These ECM fungi may be important for the establishment of pioneer woody plant species and further revegetation at Mt. Usu volcano.     

寒温带地区典型森林类型中外生菌根真菌多样性和群落组成及其影响因素

外生菌根(ECM)真菌可促进宿主植物对土壤中水分和营养的吸收,提高宿主植物的抗逆性及对环境的适应,在森林生态系统的物质循环中发挥了重要作用。为探明寒温带地区ECM真菌多样性和群落组成以及土壤理化因子对真菌群落组成的可能影响机制,采用高通量测序(Illumina Miseq)平台对大兴安岭4种典型森林类型白桦、樟子松、兴安落叶松和偃松的根围土壤ECM真菌群落组成进行了分析。结果表明,4种典型森林类型根围土壤中共获得167个ECM真菌可操作分类单元(OTUs),隶属于2个门、4个纲、10个目、24个科、36个属。在门水平上,担子菌门(Basidiomycota)真菌的相对丰度占96.4%,子囊菌门(Ascomycota)真菌占3.6%。在属水平上,红菇属(Russula,30.2%)、丝膜菌属(Cortinarius,17.1%)、Piloderma(9.6%)、棉革菌属(Tomentella,7.2%)、丝盖伞属(Inocybe,7.2%)和蜡壳耳属(Sebacina,6.2%)的相对丰度均>5.0%,是该地区的优势ECM真菌类群。不同森林类型的优势ECM真菌在属水平上的组成存在显...     

Ectomycorrhizal community structure of different genotypes of Scots pine under forest nursery conditions

In this paper, we report the effect of Scots pine genotypes on ectomycorrhizal (ECM) community and growth, survival, and foliar nutrient composition of 2-year-old seedlings grown in forest bare-root nursery conditions in Lithuania. The Scots pine seeds originated from five stands from Latvia (P1), Lithuania (P2 and P3), Belarus (P4), and Poland (P5). Based on molecular identification, seven ECM fungal taxa were identified: Suillus luteus and Suillus variegatus (within the Suilloid type), Wilcoxina mikolae, Tuber sp., Thelephora terrestris, Cenococcum geophilum, and Russuloid type. The fungal species richness varied between five and seven morphotypes, depending on seed origin. The average species richness and relative abundance of most ECM morphotypes differed significantly depending on pine origin. The most essential finding of our study is the shift in dominance from an ascomycetous fungus like W. mikolae in P2 and P4 seedlings to basidiomycetous Suilloid species like S. luteus and S. variegatus in P1 and P5 seedlings. Significant differences between Scots pine origin were also found in seedling height, root dry weight, survival, and concentration of C, K, Ca, and Mg in the needles. The Spearman rank correlation coefficient revealed that survival and nutritional status of pine seedlings were positively correlated with abundance of Suilloid mycorrhizas and negatively linked with W. mikolae abundance. However, stepwise multiple regression analysis showed that only survival and magnesium content in pine needles were significantly correlated with abundance of ECM fungi, and Suilloid mycorrhizas were a main significant predictor. Our results may have implications for understanding the physiological and genetic relationship between the host tree and fungi and should be considered in management decisions in forestry and ECM fungus inoculation programs.     

Primary succession of Bistorta vivipara (L.) Delabre (Polygonaceae) root‐associated fungi mirrors plant succession in two glacial chronosequences

Glacier chronosequences are important sites for primary succession studies and have yielded well‐defined primary succession models for plants that identify environmental resistance as an important determinant of the successional trajectory. Whether plant‐associated fungal communities follow those same successional trajectories and also respond to environmental resistance is an open question. In this study, 454 amplicon pyrosequencing was used to compare the root‐associated fungal communities of the ectomycorrhizal (ECM) herb Bistorta vivipara along two primary succession gradients with different environmental resistance (alpine versus arctic) and different successional trajectories in the vascular plant communities (directional replacement versus directional non‐replacement). At both sites, the root‐associated fungal communities were dominated by ECM basidiomycetes and community composition shifted with increasing time since deglaciation. However, the fungal community's successional trajectory mirrored the pattern observed in the surrounding plant community at both sites: the alpine site displayed a directional‐replacement successional trajectory, and the arctic site displayed a directional‐non‐replacement successional trajectory. This suggests that, like in plant communities, environmental resistance is key in determining succession patterns in root‐associated fungi. The need for further replicated study, including in other host species, is emphasized.     

Quercus rubra-associated ectomycorrhizal fungal communities of disturbed urban sites and mature forests

The presence and quality of the belowground mycorrhizal fungal community could greatly influence plant community structure and host species response. This study tests whether mycorrhizal fungal communities in areas highly impacted by anthropogenic disturbance and urbanization are less species rich or exhibit lower host root colonization rates when compared to those of less disturbed systems. Using a soil bioassay, we sampled the ectomycorrhizal fungal (EMF) communities associating with Quercus rubra (northern red oak) seedlings in soil collected from seven sites: two mature forest reference sites and five urban sites of varying levels of disturbance. Morphological and polymerase chain reaction–restriction fragment length polymorphism analyses of fungi colonizing root tips revealed that colonization rates and fungal species richness were significantly lower on root systems of seedlings grown in disturbed site soils. Analysis of similarity showed that EMF community composition was not significantly different among several urban site soils but did differ significantly between mature forest sites and all but one urban site. We identified a suite of fungal species that occurred across several urban sites. Lack of a diverse community of belowground mutualists could be a constraint on urban plant community development, especially of late-successional woodlands. Analysis of urban EMF communities can add to our understanding of urban plant community structure and should be addressed during ecological assessment before pragmatic decisions to restore habitats are framed.     

Whose truffle is this? Distribution patterns of ectomycorrhizal fungal diversity in Tuber melanosporum brûlés developed in multi‐host Mediterranean plant communities

In the Mediterranean region, patches of vegetation recovering from disturbance and transiently dominated by shrubs produce one of the world's most prized fungi, the black truffle (Tuber melanosporum). In these successional plant communities, we have fragmentary knowledge of the distribution of T. melanosporum in space among ectomycorrhizal (ECM) host species and in time. Molecular identification of hosts (Restriction Fragment Length Polymorphism) and fungi (Internal Transcribed Spacer sequencing) and quantification of T. melanosporum mycelium (quantitative Polymerase Chain Reaction) were employed to evaluate the presence of T. melanosporum on four dominant ECM host species (Quercus ilex, Quercus coccifera, Arbutus unedo, Cistus albidus) and the extent to which their respective ECM communities shared fungal diversity, over the course of development of truffle grounds, from recent unproductive brûlés to senescent ones where production has stopped. We found that truffle grounds host rich communities in which multi‐host fungal species dominate in frequency. When considering both ECM tips and soil mycelia, we documented a dynamic and spatially heterogeneous pattern of T. melanosporum distribution in soils and a presence of ECM tips restricted to Q. ilex roots. This study advances our knowledge of the ecology of T. melanosporum, and provides insight into the extent of ECM fungal sharing among plant species that dominate Mediterranean landscapes.     

How are plant and fungal communities linked to each other in belowground ecosystems? A massively parallel pyrosequencing analysis of the association specificity of root-associated fungi and their host plants

In natural forests, hundreds of fungal species colonize plant roots. The preference or specificity for partners in these symbiotic relationships is a key to understanding how the community structures of root‐associated fungi and their host plants influence each other. In an oak‐dominated forest in Japan, we investigated the root‐associated fungal community based on a pyrosequencing analysis of the roots of 33 plant species. Of the 387 fungal taxa observed, 153 (39.5%) were identified on at least two plant species. Although many mycorrhizal and root‐endophytic fungi are shared between the plant species, the five most common plant species in the community had specificity in their association with fungal taxa. Likewise, fungi displayed remarkable variation in their association specificity for plants even within the same phylogenetic or ecological groups. For example, some fungi in the ectomycorrhizal family Russulaceae were detected almost exclusively on specific oak (Quercus) species, whereas other Russulaceae fungi were found even on “non‐ectomycorrhizal” plants (e.g., Lyonia and Ilex). Putatively endophytic ascomycetes in the orders Helotiales and Chaetothyriales also displayed variation in their association specificity and many of them were shared among plant species as major symbionts. These results suggest that the entire structure of belowground plant–fungal associations is described neither by the random sharing of hosts/symbionts nor by complete compartmentalization by mycorrhizal type. Rather, the colonization of multiple types of mycorrhizal fungi on the same plant species and the prevalence of diverse root‐endophytic fungi may be important features of belowground linkage between plant and fungal communities.     

Ectomycorrhizal fungi in Mexican Alnus forests support the host co-migration hypothesis and continental-scale patterns in phylogeography

To examine the geographic patterns in Alnus-associated ectomycorrhizal (ECM) fungal assemblages and determine how they may relate to host plant biogeography, we studied ECM assemblages associated with two Alnus species (Alnus acuminata and Alnus jorullensis) in montane Mexico and compared them with Alnus-associated ECM assemblages located elsewhere in the Americas. ECM root samples were collected from four sites in Mexico (two per host species), identified with ITS and LSU rRNA gene sequences, and assessed using both taxon- (richness, diversity, evenness indices) and sequence divergence-based (UniFrac clustering and significance) analyses. Only 23 ECM taxa were encountered. Clavulina, an ECM lineage never before reported with Alnus, contained the dominant taxon overall. ECM assemblage structure varied between hosts, but UniFrac significance tests indicated that both associated with similar ECM lineage diversity. There was a strikingly high sequence similarity among a diverse array of the ECM taxa in Mexico and those in Alnus forests in Argentina, the United States, and Europe. The Mexican and United States assemblages had greater overlap than those present in Argentina, supporting the host–ECM fungi co-migration hypothesis from a common north temperate origin. Our results indicate that Alnus-associated ECM assemblages have clear patterns in richness and composition across a wide range of geographic locations. Additional data from boreal western North America as well as the eastern United States and Canada will be particularly informative in further understanding the co-biogeographic patterns of Alnus and ECM fungi in the Americas.     

Host plant species effects on arbuscular mycorrhizal fungal communities in tallgrass prairie

Symbiotic associations between plants and arbuscular mycorrhizal (AM) fungi are ubiquitous in many herbaceous plant communities and can have large effects on these communities and ecosystem processes. The extent of species-specificity between these plant and fungal symbionts in nature is poorly known, yet reciprocal effects of the composition of plant and soil microbe communities is an important assumption of recent theoretical models of plant community structure. In grassland ecosystems, host plant species may have an important role in determining development and sporulation of AM fungi and patterns of fungal species composition and diversity. In this study, the effects of five different host plant species [Poa pratensis L., Sporobolus heterolepis (A. Gray) A. Gray, Panicum virgatum L., Baptisia bracteata Muhl. ex Ell., Solidago missouriensis Nutt.] on spore communities of AM fungi in tallgrass prairie were examined. Spore abundances and species composition of fungal communities of soil samples collected from patches within tallgrass prairie were significantly influenced by the host plant species that dominated the patch. The AM fungal spore community associated with B. bracteata showed the highest species diversity and the fungi associated with Pa. virgatum showed the lowest diversity. Results from sorghum trap cultures using soil collected from under different host plant species showed differential sporulations of AM fungal species. In addition, a greenhouse study was conducted in which different host plant species were grown in similar tallgrass prairie soil. After 4 months of growth, AM fungal species composition was significantly different beneath each host species. These results strongly suggest that AM fungi show some degree of host-specificity and are not randomly distributed in tallgrass prairie. The demonstration that host plant species composition influences AM fungal species composition provides support for current feedback models predicting strong regulatory effects of soil communities on plant community structure. Differential responses of AM fungi to host plant species may also play an important role in the regulation of species composition and diversity in AM fungal communities. Received: 29 January 1999 / Accepted: 20 October 1999     

Land use practices and ectomycorrhizal fungal communities from oak woodlands dominated by Quercus suber L. considering drought scenarios

Oak woodlands in the Mediterranean basin have been traditionally converted into agro-silvo-pastoral systems and exemplified sustainable land use in Europe. In Portugal, in line with the trend of other European countries, profound changes in management options during the twentieth century have led to landscape simplification. Landscapes are dynamic and the knowledge of future management planning combining biological conservation and soil productivity is needed, especially under the actual scenarios of drought and increasing evidence of heavy oak mortality. We examined the ectomycorrhizal (ECM) fungal community associated with cork oak in managed oak woodlands (called montado) under different land use practices, during summer. ECM fungal richness and abundance were assessed in 15 stands established in nine montados located in the Alentejo region (southern Portugal), using morphotyping and ITS rDNA analysis. Parameters related to the montados landscape characteristics, land use history over the last 25 years, climatic and edaphic conditions were taken into account. Fifty-five ECM fungal taxa corresponding to the most abundant fungal symbionts were distinguished on cork oak roots. Cenococcum geophilum and the families Russulaceae and Thelephoraceae explained 56% of the whole ECM fungal community; other groups were represented among the community: Cortinariaceae, Boletaceae, Amanita, Genea, Pisolithus, Scleroderma, and Tuber. There were pronounced differences in ECM fungal community structure among the 15 montados stands: C. geophilum was the only species common to all stands, tomentelloid and russuloid species were detected in 87–93% of the stands, Cortinariaceae was detected in 60% of the stands, and the other groups were more unequally distributed. Ordination analysis revealed that ECM fungal richness was positively correlated with the silvo-pastoral exploitation regime and low mortality of cork oak, while ECM fungal abundance was positively correlated with extensive agro-silvo-pastoral exploitation under a traditional 9-year rotation cultivation system and recent soil tillage. The effects of land use on the ECM fungal community and its implications in different scenarios of landscape management options, oak mortality, and global warming are discussed.     

Long‐term increase in snow depth leads to compositional changes in arctic ectomycorrhizal fungal communities

Many arctic ecological processes are regulated by soil temperature that is tightly interconnected with snow cover distribution and persistence. Recently, various climate‐induced changes have been observed in arctic tundra ecosystems, e.g. shrub expansion, resulting in reduction in albedo and greater C fixation in aboveground vegetation as well as increased rates of soil C mobilization by microbes. Importantly, the net effects of these shifts are unknown, in part because our understanding of belowground processes is limited. Here, we focus on the effects of increased snow depth, and as a consequence, increased winter soil temperature on ectomycorrhizal (ECM) fungal communities in dry and moist tundra. We analyzed deep DNA sequence data from soil samples taken at a long‐term snow fence experiment in Northern Alaska. Our results indicate that, in contrast with previously observed responses of plants to increased snow depth at the same experimental site, the ECM fungal community of the dry tundra was more affected by deeper snow than the moist tundra community. In the dry tundra, both community richness and composition were significantly altered while in the moist tundra, only community composition changed significantly while richness did not. We observed a decrease in richness of Tomentella, Inocybe and other taxa adapted to scavenge the soil for labile N forms. On the other hand, richness of Cortinarius, and species with the ability to scavenge the soil for recalcitrant N forms, did not change. We further link ECM fungal traits with C soil pools. If future warmer atmospheric conditions lead to greater winter snow fall, changes in the ECM fungal community will likely influence C emissions and C fixation through altering N plant availability, fungal biomass and soil‐plant C‐N dynamics, ultimately determining important future interactions between the tundra biosphere and atmosphere.