Ectomycorrhiza Fungi Research Articles

Temporal variation of mycorrhization rates in a tree diversity experiment.

While mycorrhization rates have been studied in different contexts, not much is known about their temporal patterns across seasons. Here, we asked how mycorrhization rates of 10 deciduous trees assessed by microscopy changed from winter to spring to early summer. We made use of a tree diversity experiment on nutrient-rich soil (former farmland) in Central Germany. In the experiment, saplings of host species with a preference for either arbuscular mycorrhiza (AM) or ectomycorrhiza (EM) were planted in monocultures, two-species, and four-species mixtures. In addition, mixtures were composed of tree species of only one mycorrhizal type or by AM/EM trees. For almost all species, with the exception of Aesculus hippocastanum and Acer pseudoplatanus (only AM), dual mycorrhization with both types (AM and EM) was found at every sampling time (December, March, and May), although the expected preferences for certain mycorrhizal types were confirmed. The sampling date had a significant influence on mycorrhization rates of both EM and AM tree species. Frequencies of EM and AM were lowest in May, but there were no differences between December and March. The causes of this seasonal variation may be associated with climate-induced differences in carbon allocation to mycorrhizal tree roots in the temperate climate. Within individual trees, mycorrhization rates by AM and EM fungi were not correlated over time, pointing to asynchronous variation between both types and to independent drivers for AM and EM mycorrhization. At the community level, mycorrhiza frequency of either of the two types became more asynchronous from two-species to four-species mixtures. Thus, increased community asynchrony in mycorrhization could be another important mechanism in biodiversity-ecosystem functioning relationships.

Impact of model assumptions on the inference of the evolution of ectomycorrhizal symbiosis in fungi

Ectomycorrhiza (ECM) is a symbiotic relation between plant and fungi that is essential for nutrient uptake of many stand forming trees. There are two conflicting views about the evolution of ECM in fungi suggesting (1) relatively few transitions to ECM followed by reversals to non-ECM, or (2) many independent origins of ECM and no reversals. In this study, we compare these, and other, hypotheses and test the impact of different models on inference. We assembled a dataset of five marker gene sequences (nuc58, nucLSU, nucSSU, rpb1, and rpb2) and 2,174 fungal taxa covering the three subphyla: Agaricomycotina, Mucoromycotina and Pezizomycotina. The fit of different models, including models with variable rates in clades or through time, to the pattern of ECM fungal taxa was tested in a Bayesian framework, and using AIC and simulations. We find that models implementing variable rates are a better fit than models without rate shift, and that the conclusion about the relative rate between ECM and non-ECM depend largely on whether rate shifts are allowed or not. We conclude that standard constant-rate ancestral state reconstruction models are not adequate for the analysis of the evolution of ECM fungi, and may give contradictory results to more extensive analyses.

Effects of mycorrhiza and hyphae on the response of soil microbial community to warming in eastern Tibetan Plateau.

The effects of mycorrhiza and its external hyphae on the response of soil microbes to global warming remain unclear. This study investigates the role of mycorrhiza and its hyphae in regulating soil microbial community under warming by examining the microbial biomass and composition in the ingrowth cores of arbuscular mycorrhiza (AM) plant, Fargesia nitida, and ectomycorrhiza (ECM) plant, Picea asperata, with/without mycorrhiza/hyphae and experimental warming. The results showed that warming significantly increased the biomass of all soil microbes (by 19.89%-137.48%) and altered the microbial composition in both plant plots without mycorrhiza/hyphae. However, this effect was weakened in the presence of mycorrhiza or hyphae. In F. nitida plots, warming did not significantly affect biomass and composition of most soil microbial groups when mycorrhiza or hyphae were present. In P. asperata plots, warming significantly increased the total and ECM fungi (ECMF) biomass in the presence of hyphae (p < 0.05) and the total, Gn, and AM fungi (AMF) biomass in the presence of mycorrhiza (p < 0.05). Meanwhile, the response of enzyme activities to warming was also altered with mycorrhiza or hyphae. Additionally, soil microbial community composition was mainly influenced by soil available phosphorus (avaP), while enzyme activities depended on soil avaP, dissolved organic carbon (DOC), and nitrate concentrations. Our results indicate that mycorrhiza and its hyphae are essential in regulating the response of microbes to warming.

Asymmetric Interaction Between Two Mycorrhizal Fungal Guilds and Consequences for the Establishment of Their Host Plants

Arbuscular mycorrhiza (AM) and ectomycorrhiza (EcM) are the most abundant and widespread types of mycorrhizal symbiosis, but there is little and sometimes conflicting information regarding the interaction between AM fungi (AMF) and EcM fungi (EcMF) in soils. Their competition for resources can be particularly relevant in successional ecosystems, which usually present a transition from AM-forming herbaceous vegetation to EcM-forming woody species. The aims of this study were to describe the interaction between mycorrhizal fungal communities associated with AM and EcM hosts naturally coexisting during primary succession on spoil banks and to evaluate how this interaction affects growth and mycorrhizal colonization of seedlings of both species. We conducted a greenhouse microcosm experiment with Betula pendula and Hieracium caespitosum as EcM and AM hosts, respectively. They were cultivated in three-compartment rhizoboxes. Two lateral compartments contained different combinations of both host plants as sources of fungal mycelia colonizing the middle compartment, where fungal biomass, diversity, and community composition as well as the growth of each host plant species’ seedlings were analyzed. The study’s main finding was an asymmetric outcome of the interaction between the two plant species: while H. caespitosum and associated AMF reduced the abundance of EcMF in soil, modified the composition of EcMF communities, and also tended to decrease growth and mycorrhizal colonization of B. pendula seedlings, the EcM host did not have such effects on AM plants and associated AMF. In the context of primary succession, these findings suggest that ruderal AM hosts could hinder the development of EcM tree seedlings, thus slowing the transition from AM-dominated to EcM-dominated vegetation in early successional stages.

Cytological comparison of mycelial aggregates of Rhizopogon roseolus with and without the ectomycorrhiza host

ABSTRACT Most cytology reports on ectomycorrhiza (ECM) have been less focused on the fungal structures, especially on the exploratory organ. This study aimed to evaluate the morphological response of explorative mycelia of ECM forming fungi with and without the occurrence of the ECM host. We assessed the mycelial aggregates of Rhizopogon roseolus which was inoculated with and without Pinus thunbergii under controlled laboratory conditions. The mycelial aggregates with the host produced strikingly complex hyphal strands relative to those without host. Light microscopy revealed that the cytology and plectology of both mycelial aggregates had the approximately similar architecture. The tubular hyphae diameter without the host was consistently larger than that with the host. This study confirmed that the septa diameter of the tubular hyphae conjunction of mycelial aggregates with the host were shorter than those without the host. In addition, partially and completely dissolved septa of the tubular hyphae were evident with and without host. We also described the thromboplerous hyphae, which have rarely been reported in vitro. These hyphae were produced in higher numbers near the fungal inoculum with and without the host. The current findings will add to the current knowledge regarding ECM fungi mycelial aggregate response to the host.

Growth and tolerance of Ilex paraguariensis A. St.-Hil. inoculated with ectomycorrhizal fungi in copper-contaminated soil

Copper (Cu) is one of the main heavy metals contaminating the soil. Plants have different behavior in terms of tolerance and toxicity to metals, being able to grow and produce even in soils contaminated with high concentrations. This study aimed to determine the influence of ectomycorrhizal fungi on the growth and tolerance of yerba mate plants grown in soil contaminated with Cu. The design was completely randomized in a factorial arrangement (4x6), with four possibilities of inoculum: without inoculum (control) and three ectomycorrhizal fungi (UFSC-PT116 — Pisolithus microcarpus, UFSC-PT132 — Pisolithus tinctorius and UFSC-SU118 — Suillus cothurnatus), with six Cu doses amended to the soil (0, 80, 160, 240, 320 and 400 mg kg-1 of Cu) in seven replicates. The height of the aerial part, the diameter of the lap, the dry mass of the aerial part and root system, the leaf area, the specific surface area of the roots, the contents of Cu in the aerial and radicular parts, the tolerance index, and mycorrhizal association were assessed. Inoculation of Ilex paraguariensis seedlings with ectomycorrhiza fungi UFSC-PT116, UFSC-PT132, and UFSC-SU118 mitigates the toxicity effect caused by the excess of Cu in the soil. The UFSC-PT116 isolate promoted the highest growth and tolerance of Ilex paraguariensis seedlings under the treatments. In general, the isolates promoted the reduction of Cu toxicity in Ilex paraguariensis plants, being an important alternative to remediate Cu-contaminated areas.

Are arbuscular-mycorrhizal Alnus incana seedlings more resistant to drought than ectomycorrhizal and nonmycorrhizal ones?

Arbuscular mycorrhizas (AMs) prevail in warm and dry climates and ectomycorrhizas (EMs) in cold and humid climates. We suggest that the fungal symbionts benefit their host plants especially in the corresponding conditions. The hypothesis tested was that AM plants are more drought-resistant than EM or nonmycorrhizal (NM) plants. Grey alder (Alnus incana (L.) Moench) seedlings were inoculated with two species of either AM or EM fungi or none. In one controlled-environment experiment, there was a watering and a drought treatment. Another set of seedlings were not watered until permanent wilting. The AM plants were somewhat smaller than EM and NM, and at the early stage of the drought treatment, the soil-moisture content was slightly higher in the AM pots. Shoot water potential was highest in the AM treatment during severe drought, while stomatal conductance and photosynthesis did not show a mycorrhizal effect. In the lethal-drought set, the AM plants maintained their leaves longer than EM and NM plants, and the AM seedlings survived longer than NM seedlings. Foliar phosphorus and sulfur concentrations remained higher in AM plants than EM or NM, but potassium, copper and iron increased in EM during drought. The root tannin concentration was lower in AM than EM and drought doubled it. Although the difference in drought resistance was not large, the hypothesis was supported by the better performance of AM plants during a severe short-term drought. Sustained phosphorus nutrition during drought in AM plants was a possible reason for this. Moreover, the higher foliar sulfur and lower metal-nutrient concentrations in AM may reflect differences in nutrient uptake or (re)translocation during drought, which merit further research. The much larger tannin concentrations in EM root systems than AM did not appear to protect the EM plants from drought. The differential tannin accumulation in AM and EM plants needs further attention.

Pilot-scale production of Boletus colossus culture for promoting the growth of Para rubber trees

Boletus colossus is an Ectomycorrhiza fungi. It grows on roots of big trees such as Rubber tree, Mango tree and etc. This mushroom grows by using the organic materials released from the roots. The moisture adsorbed on the fungi makes the roots resist the drought better. The mushroom can also turn some insoluble inorganic materials into the form that plants can make use of. This research is to study the production of the starter culture by using low-cost media. The result shows that the fungi can grow best in whey to 9.2 g/L (dry weight) in 10 days. The liquid broth can inhibit the growth of pathogens (Alternaría brasicola, Alternaría pori, and Fusarium solani) on Potato-Dextrose agar. The starter culture can also be produced in a 50L fermenter to the dry weight of 8.1 g/L in 6 days. Loam is the best as solid carrier followed by peat moss. The result in one year shows that the Para rubber trees grow with the fungi that have significantly longer stems, leaves, and roots.

Application of Ectomycorrhiza (Scleroderma sp.) in Mangium (Acacia Mangium Willd.) using Artisanal Small-scale Gold Mining(ASGM) Tailings

Artisanal small-scale gold mining tailings frequently used hazardous toxic materials that could contaminate land, rivers, and lakes which harmful to the environment and health. Phytoremediation is one way to overcome the mining waste. Mangium (Acacia mangium Willd.) is one of plant that often used for mining land phytoremediation. However, it was difficult for mangium to be able to survive on land with such extreme conditions, therefore additional input is needed. Using ectomycorrhiza fungi could be an alternative. This study aimed to measure the adaptation of mangium in gold mining tailings and analyze the function of ectomycorrhiza (Scleroderma sp.) in the growth of mangium. The experimental design used a completely randomized design with six growth media as treatments with five replications. The growth media used were: (1) topsoil with mycorrhiza, (2) topsoil without mycorrhiza, (3) topsoil + tailings with mycorrhiza, (4) soil + tailings without mycorrhiza,(5) tailings with mycorrhiza, and (6) tailings without mycorrhiza. Data were analyzed statistically using analysis of variance followed with a Least Significant Difference test. The results showed that the survival rate of mangium life in tailing media with mycorrhizae was fairly high with a percentage of life reaching 60% even though the growth was less when compared to topsoil media with mycorrhiza that reached 100%. The highest growth rate was achieved by mangium in topsoil media without tailings and mycorrhiza (control). This research showed that ectomycorrhiza did not have any significant effects on mangium growth in gold tailing.Keywords: Acacia mangium, ectomycoriza, gold tailings, phytoremediation, Scleroderma sp.

The Effect of Scleroderma columnare Inoculum Doses to Enhance Ectomycorrhizal Colonization and Growth of Shorea javanica Seedling

Ectomycorrhiza helped plants to absorb nutrients and water. Shorea javanica belong to Dipterocarpaceae family and highly dependent on ectomycorrhiza to growth. Spore inoculation was one way to inoculate ectomycorrhiza fungi. This study aimed to get the best doses of spore Scleroderma columnare on colonization and enhancing growth of Shorea javanica seedling. This experiment used randomized complete design with 5 treatments and 3 replicates. The treatments were 0, 5, 10, 15, and 20 ml/polybag spore inoculum of S. columnare. Data obtained were analyzed by analysis of variance (anova) and continued with Least Significant Different (LSD). The results showed that added of 10 ml (6,5 x 107) gained higher root colonizatition (%). Dosis of 10 ml (6,5 x 107) and 20 ml (1,3 x 108) spore inoculum were able to improve plant growth on the parameters such as plant height, shoot dry weight, total dry weight, and total leaf area. Keywords: Dose of Inoculum, ectomycorrhiza, Scleroderma columnare, Shorea javanica.

First harvest of Périgord black truffle in the UK as a result of climate change

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 74:67-70 (2017) - DOI: https://doi.org/10.3354/cr01494 NOTE First harvest of Périgord black truffle in the UK as a result of climate change Paul Thomas1,*, Ulf Büntgen2,3,4 1Mycorrhizal Systems Ltd, Leyland, Lancashire PR25 2SD, UK 2Department of Geography, University of Cambridge, Cambridge CB2 3EN, UK 3Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland 4CzechGlobe & Department of Geography, Masaryk University, 61137 Brno, Czech Republic *Corresponding author: paul@plantationsystems.com ABSTRACT: Although some truffle species are among the most expensive gourmet foods, much of their biology and ecology is still poorly understood. Here, we provide the first record of cultivation of the Périgord black truffle Tuber melanosporum in the UK - the most northern and maritime Périgord truffle ever cultivated. This raises hopes of counteracting the ongoing, long-term, drought-induced harvest decline of this gastronomic icon species in its natural Mediterranean habitat. More generally, we detail how the UK’s first Périgord truffle find may help protect this coveted and extremely valuable product from the impacts of ongoing and predicted global warming. Finally, we address the potential sizeable economic importance of black truffle cultivation in the northern maritime climate of the British Isles, which implies a strong financial incentive for a variety of conservation initiatives. KEY WORDS: Climate change · Truffle cultivation · Ectomycorrhiza fungi · Geographical distribution · Truffle ecology · Tuber melanosporum · Périgord truffle · UK Full text in pdf format PreviousNextCite this article as: Thomas P, Büntgen U (2017) First harvest of Périgord black truffle in the UK as a result of climate change. Clim Res 74:67-70. https://doi.org/10.3354/cr01494 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 74, No. 1. Online publication date: November 02, 2017 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2017 Inter-Research.

Does severe soil drought have after-effects on arbuscular and ectomycorrhizal root colonisation and plant nutrition?

Arbuscular (AM) and ectomycorrhizas (EM) predominate in different soils. We hypothesise that also climatic factors affect directly their relative success and AM fungi (AMF) generally tolerate drought better than EM fungi (EMF). Here we tested the colonisation rates of soil-borne AMF and EMF after soil drought treatments. Forest and meadow soils were mixed to include AMF and EMF propagules. There were three soil treatments: soil moisture corresponding to 60% (control) or 10% in mass of maximum water retention, or air-dry. The bait plants were EM-forming silver birch (Betula pendula), dual-mycorrhiza forming grey alder (Alnus incana) and AM-forming white clover (Trifolium repens). After re-watering, bait plants were sown and grown in a growth chamber in favourable conditions. This way, host-plant responses to drought were eliminated. Previous soil drought decreased EM colonisation in alder. The spore formation by AMF in clover was negatively affected after the most severe soil drought treatment, suggesting slightly retarded AM formation. Soluble soil potassium concentrations were lower in drought-treated soils and this was reflected in birch foliar concentrations. The results provide some support to the hypothesised better drought tolerance of AMF than EMF propagules but further studies in milder drought and in other plant-fungus combinations are needed.

Ectomycorrhizal symbiosis enhances tolerance to low phosphorous through expression of phosphate transporter genes in masson pine (Pinus massoniana)

Ectomycorrhizal symbiosis promotes the growth of masson pine (Pinus massoniana) in low-phosphorus (low-P) conditions; however, the mechanism underlying this phenomenon has not yet been fully described. Here, we cloned four members of the Pht1 phosphate transporter protein family (GenBank accession: AMR43649.1 to AMR43652.1) encoding phosphate transporters in masson pine (PmPTs) by rapid amplification of cDNA ends (RACE) and characterized them in Boletus edulis and Pisolithus tinctorius colonized plants under low-P stress. PmPT1 to PmPT4 encoded 548, 548, 535, 535 amino acid polypeptides, respectively, containing the typical domain of the Pi:H+ symporter (PHS-transporter). Homology multiple sequence alignment indicated that these PmPTs were highly similar to phosphate transporters from other species. The polypeptides were characterized by high hydropathicity and contained 12 putative intra-membrane regions and 1 cytoplasmic loop. The temporal and spatial expression profiles showed higher expression of these PmPTs in ectomycorrhiza (ECM)-inoculated plants compared to non-inoculated ones. In addition, expressions of these PmPT members shared a similar pattern and might be intensively activated by low-P stress or inhibited under P excess. Interestingly, the ECM-colonized plants accumulated more phosphate compared to non-ECM-colonized specimens when exposed to low-P. Therefore, enhanced low-P tolerance in ECM-inoculated masson pine to low-P stress was at least partially dependent on the up-regulation of phosphate transporter genes, reflecting that the intimate interaction between plants and ECM fungi resulted in the improvement of P nutrition.

Peering into the Mediterranean black box: Lactifluus rugatus ectomycorrhizas on Cistus.

We describe the morpho-anatomical features of the ectomycorrhizas (ECMs) formed by Lactifluus rugatus on Cistus, a genus of about 20 species of woody shrubs typical of the Mediterranean maquis. The description of L. rugatus mycorrhizas on Cistus is the first ECM description of a species belonging to Lactifluus subgen. Pseudogymnocarpi. The ECM identity was verified through molecular tools. Anatomically, the characteristic of L. rugatus mycorrhiza is the presence of abundant, long "bottle-shaped" cystidia on mantle surface. Indeed, the overwhelming majority of milkcap mycorrhizas are acystidiate. This is the third Lactarius/Lactifluus mycorrhiza to have been described associated with Cistus, the others being Lactarius cistophilus and L. tesquorum. The phylogenetic distance between all these taxa is reflected by the diversity of the principal features of their ECMs, which share host-depending ECM features known for Cistus, but are otherwise distinguishable on the host roots. Comparison of Lactifluus rugatus ECM with those formed by L. vellereus and L. piperatus on Fagus reveals elevated intrageneric diversity of mycorrhizal structures. Such a diversity is supported by analysis of ITS sequences of relevant species within European Lactifluus species. Our study extends knowledge of Cistus mycorrhizal biology and confirms the informative value of mycorrhizal structures in understanding phylogenetic relationships in ECM fungi.

Plants, fungi and oomycetes: a 400‐million year affair that shapes the biosphere

Plants, fungi and oomycetes: a 400‐million year affair that shapes the biosphere

Enhancing our understanding of anatomical diversity in Tomentella ectomycorrhizas: characterization of six new morphotypes.

Ectomycorrhizas (ECM) formed by Tomentella species (Thelephorales, Basidiomycota) were collected in beech forests of Hungary and studied using anatomical and molecular phylogenetic methods. The mycobionts were identified by analysing the sequences of nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) regions together with sequences obtained from public databases. At the sampling plots, we found the occurrence of 11 Tomentella morphotypes. Among these, six morphotypes (four identified, Tomentella atroarenicolor, Tomentella bryophila, Tomentella lapida, Tomentella subclavigera, and two unidentified) were morpho-anatomically characterized for the first time. Although the six morphotypes differed anatomically from each other and from Tomentella ectomycorrhizas described previously, they shared anatomical features common to tomentelloid ectomycorrhizas fungi. These results expand our understanding of the diversity of this widely distributed ectomycorrhizal genus.

Diversity and host associations of ectomycorrhizae fungi in fallow lands of the mid-Zambezi valley area, Zimbabwe

Fallowing creates land mosaics characterised by vegetation communities at different stages of succession. Such mosaics are expected to harbour mycorrhizal associations that reflect host species composition and diversity. We investigated the diversity of ectomycorrhizal fungi and their host associations across a fallow crono-sequence of 1–14 years in the mid-Zambezi valley area, Zimbabwe. Five ectomycorrhizal fungi species: Lactarius gymnocarpus, Lactarius sp., Boletus sp., Thelephora terrestris and Amphinema byssoides were recorded from 13 tree species from six families: Combretaceae, Ebenaceae, Fabaceae, Simaroubaceae, Rhamnaceae and Tiliaceae. The results indicated low host specificity among the observed ectomycorrhizal fungi. A Spearman Rank correlation test showed no significant correlation (p > 0.05) between fallow age and ectomycorrhizal status. The Raup–Crick similarity cluster indicated an interaction between fallow age and ectomycorrhizal fungi status on tree species. Our results support reports on low host specificity for ectomycorrhizal fungi among tropical African plant communities.

Former Land Use and Host Genotype Influence the Mycorrhizal Colonization of Poplar Roots

The present paper analyses the community structure of ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM) fungi associated with seven different poplar clone types growing in a patch system on soil from four different former land use types, originating from spruce forest, poplar stand, grassland and cornfield. We determined the extent to which ECM and AM play a role on the studied factors (genotype, former land use type and host growth). The diversity of ECM and AM fungal communities was estimated by morphological and molecular analyses of the 18S and ITS of the rDNA genes. Fifteen ECM fungal taxa and four AM groups were distinguished in the roots of the poplars grown for 18 months on soil originating from the respective land use types. The poplar clones showed significantly different rates of shoot length and AM colonization, especially concerning the occurrence of Glomus intraradices and Scutellospora sp. Populus deltoides had significantly higher Scutellospora sp. abundance. Although ECM abundance and diversity was high, no significant differences between the different land use types was found. However, some ECM fungi like Paxillus involutus, Laccaria proxima and Laccaria tortilis showed significant preferences for specific land use types. Our findings suggest that both factors, former land use type and poplar genotype, are important determinants of mycorrhizal colonization of the host plants.

Inhibitory potential of naphthoquinones leached from leaves and exuded from roots of the invasive plant Impatiens glandulifera.

Exploring the effects of allelopathic plant chemicals on the growth of native vegetation is essential to understand their ecological roles and importance in exotic plant invasion. Naphthoquinones have been identified as potential growth inhibitors produced by Impatiens glandulifera, an exotic annual plant that recently invaded temperate forests in Europe. However, naphthoquinone release and inhibitory potential have not been examined. We quantified the naphthoquinone content in cotyledons, leaves, stems, and roots from plants of different ages of both the invasive I. glandulifera and native Impatiens noli-tangere as well as in soil extracts and rainwater rinsed from leaves of either plant species by using ultra-high pressure liquid chromatography-mass spectrometry (UHPLC-MS). We identified the compound 2-methoxy-1,4-naphthoquinone (2-MNQ) exclusively in plant organs of I. glandulifera, in resin bags buried into the soil of patches invaded by I. glandulifera, and in rainwater rinsed from its leaves. This indicates that 2-MNQ is released from the roots of I. glandulifera and leached from its leaves by rain. Specific bioassays using aqueous shoot and root extracts revealed a strong inhibitory effect on the germination of two native forest herbs and on the mycelium growth of three ectomycorrhiza fungi. These findings suggest that the release of 2-MNQ may contribute to the invasion success of I. glandulifera and support the novel weapons hypothesis.

Microbial community structure of soils under four productivity classes of aspen forests in northern British Columbia

Trembling aspen (Populus tremuloides) is widely distributed in North American forests. Increased stand productivity with resource availability has been reported, but the relationship between soil microbial community structure and stand productivity remains unclear. To examine soil microbial composition of 4 aspen stand productivity classes, we assessed soil properties, microbial biomass and respiration, and bacterial and ectomycorrhizal diversity. Most variables showed no significant differences between productivity classes. However, mean values for basal respiration (0.05 to 27.99 μg CO2-C·g−1 soil·h−1), bacterial biomass, and metabolic quotient (0.08 to 5.22 CO2-C·mg−1 Cmic·h−1) were lowest in low productivity (Class 1) sites. Bacteria to fungi ratios were significantly lower (P = 0.05) in Class 1 compared to other classes. Microbial biomass ranged from 1.39 to 8.11 mg Cmic·g−1 soil. Thirty-seven distinct aspen ectomycorrhizas (ECM) were characterized, 21 were considered rare (from ≤3 trees). ECM richness did not differ significantly between classes, although relative abundance for some types did. Canonical correspondence analysis showed productivity class explained most microbial community variation, e.g., ECM fungi (80% explained) and soil bacteria (46%). Despite some differences, we could not identify statistically significant bacterial or ECM assemblages linked to stand productivity. Results may reflect a strong association between microbial processes and the dominant host, aspen. Aspen associated with widely distributed fungi common to all classes, possibly facilitating its survival and growth, including on sites exhibiting low pH and low soil fertility.