Into the void: ECM fungal communities involved in the succession from rockroses to oak stands

Oak forests accompanied by Cistus species are a common landscape in the Mediterranean basin. It is argued that Cistus dominated fields serve as recruitment areas for Quercus seedlings, as they help in the transmission of the fungal community through vegetative succession in these ecosystems. To test these assumptions, we analyzed the fungal community in terms of its richness and composition, taking into account the effects of host (Oaks vs. Cistus) and forest structure, mainly based on age. Edaphic variables related to the different structures were also analyzed to examine how they evolve through succession and relate to shifts in the fungal community. No differences in fungal richness were observed between old Cistus stands and younger Quercus, while a brief increase in ECM richness was observed. Community composition also showed a greater overlap between old Cistus and young Quercus stands. We suggest that the most important step in fungal transfer from one host to another is the shift from the oldest Cistus fields to the youngest Quercus stands, with the genera Amanita, Cortinarius, Lactarius, Inocybe, Russula, and Tomentella probably playing a major role. In summary, our work has also revealed the network of fungal community structure in the succession of Cistus to Oak stands, it would suggest that the fungi share niches and significantly enhance the ecological setting of the transition from Cistus to Oak stands.

Unravelling the French National Fungal Database: Geography, Temporality, Taxonomy and Ecology of the Recorded Diversity

Large datasets are highly valuable resources to investigate multi-scale patterns of organisms, and lay foundations for citizen science-based conservation strategies. Here, we used 1,043,262 records from 1708 to 2021 to explore the geography, taxonomy, ecology and distribution patterns of 11,556 fungal taxa in metropolitan France. Our analysis reveals a four-phase pattern of temporal recording, with a main contribution of post-1977 observations in relation with the structuration of associative mycology. The dataset shows an uneven geography of fungal recording. Four clusters of high-intensity sampling scattered across France contrast with poorly documented areas, including the Mediterranean. Basidiomycota and Agaricales highly dominate the dataset, accounting for 88.8 and 50.4% of records, respectively. The dataset is composed of many rare taxa, with 61.2% of them showing fewer than 100 records, and 20.5% recorded only once. The analysis of metadata brings to light a preponderance of the mycorrhizal guild (44.6%), followed by litter saprotrophs (31.6%) and wood saprotrophs (18.1%). Highly documented forests (76.3% of records) contrast with poorly investigated artificial (6.43%) and open habitats (10.1%). This work provides the first comprehensive overview of fungal diversity in France and identifies the Mediterranean area and open habitats as priorities to integrate into a global strategy for fungal conservation in France.

Systematic revision of the Roseinae clade of Russula, with a focus on eastern North American taxa

The Roseinae clade is a lineage of the genus Russula primarily composed of species of Russula subsect. Roseinae. Species in this morphologically distinct clade possess a white to pale cream spore print, mild taste, positive reaction to sulfovanillin, and primordial hyphae with acid-resistant crystals in the pileipellis. Here, we present a morphological and phylogenetic assessment that distinguishes seven eastern North American species of the core Roseinae lineage and a new subsection, Russula subsection Albidinae, to accommodate members of the Albida clade. We assign the previously described species R. peckii, R. rubellipes, and R. pseudopeckii to three species-level clades, and three other species, R. cardinalis, R. cordata, and R. rheubarbarina, are described as new. Comparative morphological analyses reveal differences in the conformation of terminal elements in the pileipellis, spore size, hymenial cystidia contents, and pigmentation on the stipe surface as key features to recognize species in the group. Based on the analysis of publicly available data, we recognize a potential total of nine temperate North American species within R. subsect. Roseinae, in addition to four from Central America, two from Europe, and 14 from Asia.

EFECTO DE BORDE EN LA DIVERSIDAD Y COLONIZACIÓN DE ECTOMICORRIZAS DE Quercus humboldtii (FAGACEAE) EN ARCABUCO- BOYACÁ-COLOMBIA

Los robledales en Colombia están dominados por la especie Quercus humboldtii Bonpl. Esta especie se encuentra en categoría de vulnerable debido a la deforestación para generar cultivos, zonas ganaderas y plantaciones de especies exóticas, ocasionando la formación de bordes por el deterioro del ecosistema. Estos bosques establecen asociaciones simbióticas con especies de hongos ectomicorrícicos, permitiendo el intercambio de nutrientes entre las hifas de los hongos y las raíces de las plantas. Este estudio analiza el efecto de borde en un área al interior (BNI-C) y al borde de un bosque de roble no intervenido (BNI-B), además de dos bordes de bosque con intervención antropogénica, una en contacto con plantación de Eucalyptus sp. (BE) y otro con ganadería (BG). Se estableció el borde de bosque mediante variables ambientales (temperatura ambiente, luminosidad temperatura y humedad del suelo). Se colectaron raicillas de siete árboles tanto de interior como de borde para medir la colonización y caracterizar morfológicamente las ectomicorrizas asociadas a las raíces de roble. Se evidenció el efecto de borde en el grado de colonización ectomicorrícica en las raíces de Q. humboldtii con porcentajes de 18 a 30 % en BNI, 15 % en BE y 47 % en BG. Los géneros ectomicorrícicos Cenococcum sp. y Lactarius sp.  presentaron la mayor abundancia en  los tres bosques, variando considerablemente cerca a los bordes en BG y BE. Se evidenciaron cambios de porcentaje de colonización y diversidad de  morfotipos de ectomicorrizas en los bordes de los dos bosques intervenidos.

Impact of urbanization on functional diversity in macromycete communities along an urban ecosystem in Southwest Mexico

Macromycetes are a group of fungi characterized by the production of fruit bodies and are highly relevant in most terrestrial ecosystems as pathogens, mutualists, and organic matter decomposers. Habitat transformation can drastically alter macromycete communities and diminish the contribution of these organisms to ecosystem functioning; however, knowledge on the effect of urbanization on macrofungal communities is scarce. Diversity metrics based on functional traits of macromycete species have shown to be valuable tools to predict how species contribute to ecosystem functionality since traits determine the performance of species in ecosystems. The aim of this study was to assess patterns of species richness, functional diversity, and composition of macrofungi in an urban ecosystem in Southwest Mexico, and to identify microclimatic, environmental, and urban factors related to these patterns in order to infer the effect of urbanization on macromycete communities. We selected four oak forests along an urbanization gradient and established a permanent sampling area of 0.1 ha at each site. Macromycete sampling was carried out every week from June to October 2017. The indices used to measure functional diversity were functional richness (FRic), functional divergence (FDig), and functional evenness (FEve). The metric used to assess variation of macrofungal ecological function along the study area was the functional value. We recorded a total of 134 macromycete species and 223 individuals. Our results indicated a decline of species richness with increased urbanization level related mainly to microclimatic variables, and a high turnover of species composition among study sites, which appears to be related to microclimatic and urbanization variables. FRic decreased with urbanization level, indicating that some of the available resources in the niche space within the most urbanized sites are not being utilized. FDig increased with urbanization, which suggests a high degree of niche differentiation among macromycete species within communities in urbanized areas. FEve did not show notable differences along the urbanization gradient, indicating few variations in the distribution of abundances within the occupied sections of the niche space. Similarly, the functional value was markedly higher in the less urbanized site, suggesting greater performance of functional guilds in that area. Our findings suggest that urbanization has led to a loss of macromycete species and a decrease in functional diversity, causing some sections of the niche space to be hardly occupied and available resources to be under-utilized, which could, to a certain extent, affect ecosystem functioning and stability.

Comparison of diversity and composition of macrofungal species between intensive mushroom harvesting and non-harvesting areas in Oaxaca, Mexico

Wild edible mushrooms have been collected and consumed by human groups for centuries, and today they represent a relevant source of food and income for many rural families worldwide. Preserving these non-timber forest products is of great interest, and there is concern about the damage caused by intensive mushroom harvesting on macromycete communities. The aim of this study was to evaluate variation in diversity and composition of macromycete species between areas regularly used for mushroom harvesting and non-harvested areas in the Mixteca region of Oaxaca, Mexico, as well as to assess the influence of microclimatic and environmental factors on this variation. We selected two harvested and two non-harvested sites within the study area. In each one, we established 10 permanent plots of 10 m × 10 m where we sampled all the observed fruit bodies weekly from June to October 2017. We recorded a total of 856 individuals corresponding to 138 species, and 23 of these were identified as edible. Overall macromycete diversity, edible species diversity and composition were similar in Sites 1 (non-harvested) and 3 (harvested), and in Sites 2 (non-harvested) and 4 (harvested). Variation of diversity and species composition along the studied area was mainly related to microclimatic variables, while most environmental variables and variables related to vegetation structure similarly affected macromycete species in the four sites. Our results indicate that intensive harvesting of wild edible mushrooms is not affecting the diversity and distribution of macromycete species in our study area. Knowledge on the sustainability of mushroom harvesting practices can help improve current regulations regarding the management of these valuable non-timber forest products.

Phylogenetic and distributional data on boletoid fungi (Boletaceae) in Cyprus and description of a new sampling methodology

The data presented here was obtained during a decade-long macromycete inventory on the island of Cyprus and is supplementary to the research article "Present status and future of boletoid fungi (Boletaceae) on the island of Cyprus: cryptic and threatened diversity unravelled by ten-year study" [1]. A new, rainfall-based sampling protocol for documenting fungal diversity in Mediterranean ecosystems, is described in detail.

Carbon stock increases up to old growth forest along a secondary succession in Mediterranean island ecosystems

The occurrence of old-growth forests is quite limited in Mediterranean islands, which have been subject to particularly pronounced human impacts. Little is known about the carbon stocks of such peculiar ecosystems compared with different stages of secondary succession. We investigated the carbon variation in aboveground woody biomass, in litter and soil, and the nitrogen variation in litter and soil, in a 100 years long secondary succession in Mediterranean ecosystems. A vineyard, three stages of plant succession (high maquis, maquis-forest, and forest-maquis), and an old growth forest were compared. Soil samples at two soil depths (0–15 and 15–30 cm), and two litter types, relatively undecomposed and partly decomposed, were collected. Carbon stock in aboveground woody biomass increased from 6 Mg ha^-1 in the vineyard to 105 Mg ha^-1 in old growth forest. Along the secondary succession, soil carbon considerably increased from about 33 Mg ha^-1 in the vineyard to about 69 Mg ha^-1 in old growth forest. Soil nitrogen has more than doubled, ranging from 4.1 Mg ha^-1 in the vineyard to 8.8 Mg ha^-1 in old growth forest. Both soil parameters were found to be affected by successional stage and soil depth but not by their interaction. While the C/N ratio in the soil remained relatively constant during the succession, the C/N ratio of the litter strongly decreased, probably following the progressive increase in the holm oak contribution. While carbon content in litter decreased along the succession, nitrogen content slightly increased. Overall, carbon stock in aboveground woody biomass, litter and soil increased from about 48 Mg ha^-1 in the vineyard to about 198 Mg ha^-1 in old growth forest. The results of this study indicate that, even in Mediterranean environments, considerable amounts of carbon may be stored through secondary succession processes up to old growth forest.

Assessment of functional and structural changes of soil fungal and oomycete communities in holm oak declined dehesas through metabarcoding analysis

Forest decline is nowadays a major challenge for ecosystem sustainability. Dehesas, which consists of savannah-like mediterranean ecosystems, are threatened by the holm oak decline in the south-west of Iberian Peninsula. Phytophthora cinnamomi is considered the main agent of holm oak root rot, but little is known about the relationship between diversity of soilborne microbial community and the decline syndrome of holm oak. It would be hypothesized that the changes in the structure and functionality of the soil microbiome might influence tree health status through changes in richness and diversity of beneficial organisms such as mycorrhizal species, or fungal plant pathogens such as Fusarium spp. or Alternaria spp. Total DNA of soil samples from declined oak dehesas was extracted and analyzed through metabarcoding techniques, to evaluate the specific composition and diversity of the fungal and oomycete communities and their relationship with the disease symptoms. The fungal community included a wide range of pathogens and abundance of ectomycorrhizal key taxa related with low defoliation degree. Phytophthora cinnamomi and Pythium spiculum did not appear among the most abundant oomycetes, nor were they related directly to defoliation levels. Moreover, a particular taxon belonging to the genus Trichoderma was strongly correlated with the scarcity of pathogenic Phytophthora spp. The diversity and composition of fungal and oomycete communities were related to the severity of the decline symptoms. The metabarcoding study of microbiome represents a powerful tool to develop biocontrol strategies for the management of the holm oak root rot.

Ectomycorrhizal Colonisation in Declining Oak Stands on the Krotoszyn Plateau, Poland

We describe the ectomycorrhizal (ECM) root tips and the diversity of mycorrhizal fungal species at three English oak (Quercus robur) sites (two 120 year old sites and one 60 year old site). The three oak stands in decline, located in western Poland, were characterized by a low degree of vital ECM colonization: 30.2%, 29.1% and 25.6% at Krotoszyn (K), Piaski (P) and Karczma Borowa (KB), respectively. DNA (ITS) barcoding revealed a total of 18 ECM fungal species. Based on exploration types, ectomycorrhizae were classified with respect to ecologically relevant features. The contact type was significantly correlated with C:N and Corg, while the short distance type was correlated with Ca, phosphorus (P2O5) and pH. The medium distance exploration type was significantly correlated with fine-grained soil particle size fractions: coarse silt (0.05–0.02 mm) and fine silt (0.02–0.002 mm), and clay (<0.002 mm). The long distance type showed a similar pattern to the medium distance smooth type, but was also correlated with nitrate (N). The values of biometric root parameters of oak trees at the analysed forest sites were arranged as follows: K > P > KB, and were opposite to the condition of the tree crowns. A negative correlation of vital ECM root tip abundance with the crown health status of oaks was observed, whereas higher ECM diversity reflected better crown health in the oak stands studied.

Tree species identity and diversity drive fungal richness and community composition along an elevational gradient in a Mediterranean ecosystem

Ecological and taxonomic knowledge is important for conservation and utilization of biodiversity. Biodiversity and ecology of fungi in Mediterranean ecosystems is poorly understood. Here, we examined the diversity and spatial distribution of fungi along an elevational gradient in a Mediterranean ecosystem, using DNA metabarcoding. This study provides novel information about diversity of all ecological and taxonomic groups of fungi along an elevational gradient in a Mediterranean ecosystem. Our analyses revealed that among all biotic and abiotic variables tested, host species identity is the main driver of the fungal richness and fungal community composition. Fungal richness was strongly associated with tree richness and peaked in Quercus-dominated habitats and Cistus-dominated habitats. The highest taxonomic richness of ectomycorrhizal fungi was observed under Quercus ilex, whereas the highest taxonomic richness of saprotrophs was found under Pinus. Our results suggest that the effect of plant diversity on fungal richness and community composition may override that of abiotic variables across environmental gradients.

Habitat- and soil-related drivers of the root-associated fungal community of Quercus suber in the Northern Moroccan forest

Soil fungi associated with plant roots, notably ectomycorrhizal (EcM) fungi, are central in above- and below-ground interactions in Mediterranean forests. They are a key component in soil nutrient cycling and plant productivity. Yet, major disturbances of Mediterranean forests, particularly in the Southern Mediterranean basin, are observed due to the greater human pressures and climate changes. These disturbances highly impact forest cover, soil properties and consequently the root-associated fungal communities. The implementation of efficient conservation strategies of Mediterranean forests is thus closely tied to our understanding of root-associated fungal biodiversity and environmental rules driving its diversity and structure. In our study, the root-associated fungal community of Q. suber was analyzed using high-throughput sequencing across three major Moroccan cork oak habitats. Significant differences in root-associated fungal community structures of Q. suber were observed among Moroccan cork oak habitats (Maâmora, Benslimane, Chefchaoun) subjected to different human disturbance levels (high to low disturbances, respectively). The fungal community structure changes correlated with a wide range of soil properties, notably with pH, C:N ratio (P = 0.0002), and available phosphorus levels (P = 0.0001). More than 90 below-ground fungal indicators (P < 0.01)-either of a type of habitat and/or a soil property-were revealed. The results shed light on the ecological significance of ubiquitous ectomycorrhiza (Tomentella, Russula, Cenococcum), and putative sclerotia-associated/ericoid mycorrhizal fungal taxa (Cladophialophora, Oidiodendron) in the Moroccan cork oak forest, and their intraspecific variability regarding their response to land use and soil characteristics.

Bacterial selection by mycospheres of Atlantic Rainforest mushrooms

This study focuses on the selection exerted on bacterial communities in the mycospheres of mushrooms collected in the Brazilian Atlantic Rainforest. A total of 24 paired samples (bulk soil vs. mycosphere) were assessed to investigate potential interactions between fungi and bacteria present in fungal mycospheres. Prevalent fungal families were identified as Marasmiaceae and Lepiotaceae (both Basidiomycota) based on ITS partial sequencing. We used culture-independent techniques to analyze bacterial DNA from soil and mycosphere samples. Bacterial communities in the samples were distinguished based on overall bacterial, alphaproteobacterial, and betaproteobacterial PCR-DGGE patterns, which were different in fungi belonging to different taxa. These results were confirmed by pyrosequencing the V4 region of the 16S rRNA gene (based on five bulk soil vs. mycosphere pairs), which revealed the most responsive bacterial families in the different conditions generated beneath the mushrooms, identified as Bradyrhizobiaceae, Burkholderiaceae, and Pseudomonadaceae. The bacterial families Acetobacteraceae, Chrhoniobacteraceae, Planctomycetaceae, Conexibacteraceae, and Burkholderiaceae were found in all mycosphere samples, composing the core mycosphere microbiome. Similarly, some bacterial groups identified as Koribacteriaceae, Acidobacteria (Solibacteriaceae) and an unclassified group of Acidobacteria were preferentially present in the bulk soil samples (found in all of them). In this study we depict the mycosphere effect exerted by mushrooms inhabiting the Brazilian Atlantic Rainforest, and identify the bacteria with highest response to such a specific niche, possibly indicating the role bacteria play in mushroom development and dissemination within this yet-unexplored environment.

Soil DNA pyrosequencing and fruitbody surveys reveal contrasting diversity for various fungal ecological guilds in chestnut orchards

Fungal diversity in Mediterranean forest soils is poorly documented, particularly when considering saprobic and pathogenic organisms. Next-generation sequencing (NGS) methods applied to soil fungi provide the opportunity to unveil the most inconspicuous functional guilds (e.g. saprobes) and life forms (e.g. Corticiaceae) of this tremendous diversity. We used fruitbody surveys over 2 years and soil 454 metabarcoding in Castanea sativa orchards to evaluate respectively the reproductive (fruitbodies) and vegetative (mycelia) parts of fungal communities in three 100-year-old stands. Analysis of 839 fruitbodies and 210 291 ITS1 reads revealed high fungal diversity, mainly shown by belowground analysis, with high (dominant) abundance of mycorrhizal fruitbodies and reads. Both methods displayed contrasted composition and structure of fungal communities, with Basidio- and Ascomycetes dominating above- and belowground, respectively. For the two dominant fungal guilds (i.e. ectomycorrhizal and saprobic), diversity above- and belowground overlapped weakly. This study is the first assessment of the complementarity of fruitbody surveys and NGS for analysing fungal diversity in Mediterranean ecosystems and shows that belowground methods still need to be completed by fruiting diversity to provide a comprehensive overview of the different fungal guilds. The results shed light on chestnut soil biodiversity and question the spatial distribution and synergies among fungal guilds.

Beyond ectomycorrhizal bipartite networks: projected networks demonstrate contrasted patterns between early- and late-successional plants in Corsica

The ectomycorrhizal (ECM) symbiosis connects mutualistic plants and fungal species into bipartite networks. While links between one focal ECM plant and its fungal symbionts have been widely documented, systemic views of ECM networks are lacking, in particular, concerning the ability of fungal species to mediate indirect ecological interactions between ECM plant species (projected-ECM networks). We assembled a large dataset of plant-fungi associations at the species level and at the scale of Corsica using molecular data and unambiguously host-assigned records to: (i) examine the correlation between the number of fungal symbionts of a plant species and the average specialization of these fungal species, (ii) explore the structure of the plant-plant projected network and (iii) compare plant association patterns in regard to their position along the ecological succession. Our analysis reveals no trade-off between specialization of plants and specialization of their partners and a saturation of the plant projected network. Moreover, there is a significantly lower-than-expected sharing of partners between early- and late-successional plant species, with fewer fungal partners for early-successional ones and similar average specialization of symbionts of early- and late-successional plants. Our work paves the way for ecological readings of Mediterranean landscapes that include the astonishing diversity of below-ground interactions.

Macrofungal diversity in community-managed sal (Shorea robusta) forests in central Nepal

Macrofungi constitute a group of the high-value forest resources worldwide. In this paper, we report species richness and composition of the macrofungi in sal (Shorea robusta) forests of mid-hill central Nepal, which were managed for 4-29 years by the local communities. The sal forests were rich in macrofungi (115 species) with Polyporaceae being the largest family followed by Clavariaceae. Saprotrophic fungi were more common than mycorrhizal species. The proportion of mycorrhiza was <40% of the total macrofungi species which might have indicated the deteriorated condition of the forests before the initiation of conservation management. However, the proportion of mycorrhizal species was slightly higher in the forests managed for >10 years than in the forests managed for short period. The species richness increased with increasing canopy and litter cover. Since silvicultural activities and resource utilization often have negative impacts to macrofungal diversity, these activities need to be optimized to keep balance between forest management and biodiversity conservation.

Correlating Mushroom Habitats and Geology in Grevena Prefecture (Greece) with the Use of Geographic Information Systems (GIS)

The aim of this study is to assess the relationship between geological background and habitats of mushrooms. The study area is Grevena, a Prefecture of Greece well known for the great variety of the fungal flora and its distinctive geology. Thematic maps of the study area were produced with the use of GIS, taking under consideration geological formations, elevation, ecosystems and land use. Findings provide evidence that certain mushrooms are more likely to be found in specific ecosystems. The connection between forest ecosystems and the geology of the study area is more apparent, as certain forest types are related with specific geological formations; due to the insignificant presence of grasslands and riverine settings in the study area, it is not possible to assess the role of the geological formation for these mushroom habitats.

A checklist of the basidiomycetous macrofungi and a record of five new species from mt. Oseo in Korea

Basidiomycetous macrofungi play important roles in maintaining forest ecosystems via carbon cycling and the mobilization of nitrogen and phosphorus. To understand the impact of human activity on macrofungi, an ongoing project at the Korea National Arboretum is focused on surveying the macrofungi in unexploited areas. Mt. Oseo was targeted in this survey because the number of visitors to this destination has been steadily increasing, and management and conservation plans for this destination are urgently required. Through 5 field surveys of Mt. Oseo from April to October 2012, 116 specimens of basidiomycetous macrofungi were collected and classified. The specimens were identified to the species level by analyzing their morphological characteristics and their DNA sequence data. A total of 80 species belonging to 57 genera and 25 families were identified. To the best of our knowledge, this is the first study to identify five of these species-Artomyces microsporus, Hymenopellis raphanipes, Pholiota abietis, Phylloporus brunneiceps, and Sirobasidium magnum-in Korea.

Fine-scale distribution of ectomycorrhizal fungi colonizing Tsuga diversifolia seedlings growing on rocks in a subalpine Abies veitchii forest

Numerous species of ectomycorrhizal (ECM) fungi coexist under the forest floor. To explore the mechanisms of coexistence, we investigated the fine-scale distribution of ECM fungal species colonizing root tips in the root system of Tsuga diversifolia seedlings in a subalpine forest. ECM root tips of three seedlings growing on the flat top surface of rocks were sampled after recording their positions in the root system. After the root tips were grouped by terminal-restriction fragment length polymorphism (T-RFLP) analysis of ITS rDNA, the fungal species representing each T-RFLP group were identified using DNA sequencing. Based on the fungal species identification, the distribution of root tips colonized by each ECM fungus was mapped. Significant clustering of root tips was estimated for each fungal species by comparing actual and randomly simulated distributions. In total, the three seedlings were colonized by 40 ECM fungal species. The composition of colonizing fungal species was quite different among the seedlings. Twelve of the 15 major ECM fungal species clustered significantly within a few centimeters. Some clusters overlapped or intermingled, while others were unique. Areas with high fungal species diversity were also identified in the root system. In this report, the mechanisms underlying generation of these ECM root tip clusters in the root system are discussed.

Studies on the ectomycorrhizal community in a declining Quercus suber L. stand

This survey was carried out in a Quercus suber L. stand with many trees affected by the disease "oak decline". Its aim was to obtain information about both the belowground ectomycorrhizal fungal community in a declining Q. suber stand as a whole, and the ectomycorrhizal fungal community of individual tree (EFT) detected in healthy and diseased plants. To this end, we first categorized the trees into four different decline classes (one for healthy plants and three for diseased plants) and then, by using morphological and molecular tools, we identified the ectomycorrhizas isolated from samples collected near the trees with different declining classes. The ectomycorrhizal community as a whole was seen to be composed of numerous ectomycorrhizal fungal species, only some of which appeared to be dominant (Cenococcum geophilum, Lactarius chrysorrheus, and some species of Tomentella genus), while most occurred sporadically. Results show that all root tips observed are mycorrhized and that decline class does not influence the number of ectomycorrhizal root tips found in the EFTs, thus oak decline does not impact the investment in ectomycorrhizal symbiosis. However, some statistical differences can be observed in the values of evenness and taxonomic distinctness in the EFT associated with trees with different states of health. Finally, both the analysis of similarity test and the ordination technique highlight a compositional difference between the EFT associated with trees in different health conditions, but also suggest that other factors may play a role in causing these differences.

Ectomycorrhizal fungal succession coincides with shifts in organic nitrogen availability and canopy closure in post-wildfire jack pine forests

Successional changes in belowground ectomycorrhizal fungal (EMF) communities have been observed with increasing forest stand age; however, mechanisms behind this change remain unclear. It has been hypothesized that declines of inorganic nitrogen (N) and increases of organic N influence changes in EMF taxa over forest development. In a post-wildfire chronosequence of six jack pine (Pinus banksiana) stands ranging in age from 5 to 56 years, we investigated EMF community composition and compared shifts in taxa with detailed soluble inorganic and organic N data. Taxa were identified by internal transcribed spacer rDNA sequencing, and changes in community composition evaluated with non-metric multi-dimensional scaling (NMDS). Dissimilarities in the community data were tested for correlations with N variables. We observed a successional shift along NMDS axis 1 from such taxa as Suillus brevipes and Thelephora terrestris in sites age 5 and 11 to species of Cortinarius and Russula, among others, in the four older sites. This change was positively correlated with soluble organic N (SON) (r(2) = 0.902, P = 0.033) and free amino-acid N (r(2) = 0.945, P = 0.021), but not inorganic N. Overall, our results show a successional shift of EMF communities occurring between stand initiation and canopy closure without a change in species of the dominant plant-host, and associated with SON and free amino-acid N in soil. It is uncertain whether EMF taxa are responding to these organic N forms directly, affecting their availability, or are ultimately responding to changes in other site variables, such as belowground productivity.

Population genetics of ectomycorrhizal fungi: from current knowledge to emerging directions

Ectomycorrhizal (EM) fungi are major microbial components of boreal, temperate and Mediterranean forests, as well as some tropical forest ecosystems. Nearly two decades of studies have clarified many aspects of their population biology, based on several model species from diverse lineages of fungi where the EM symbiosis evolved, i.e. among Hymenomycetes and, to a lesser extent, among Ascomycetes. In this review, we show how tools for individual recognition have changed, shifting from the use of somatic incompatibility reactions to dominant and non-specific markers (such as random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP)) and, more recently, to co-dominant and specific markers (such as microsatellites and single nucleotide polymorphisms (SNPs)). At the same time, the theoretical focus has also changed. In earlier studies, a major aim was the description of genet size and popul/ation strategy. For example, we show how some studies supported or challenged the simple, classical model of colonization of new forest stands by ruderal (R) species, propagating by spores and forming small genets, progressively replaced in older forests by more competitive (C) species, propagating by mycelial growth and forming larger genets. By contrast, more recent studies give insights into some genetic traits, such as partners' assortment (allo- versus autogamy), genetic structure of populations and gene flow that turn out to depend both on distance and on whether spores are animal- or wind-dispersed. We discuss the rising awareness that (i) many morphospecies contain cryptic biological species (often sympatric) and (ii) trans- and inter-continental species may often contain several biological species isolated by distance. Finally, we show the emergence of biogeographic approaches and call for some aspects to be developed, such as fine-scale and long-term population monitoring, analyses of subterranean populations of extra-radical mycelia, or more model species from the tropics, as well as from the Ascomycetes (whose genetic idiosyncrasies are discussed). With the rise of the '-omics' sciences, analysis of population structure for non-neutral genes is expected to develop, and forest management and conservation biology will probably profit from published and expected work.

Epigeous fruiting bodies of ectomycorrhizal fungi as indicators of soil fertility and associated nitrogen status of boreal forests

Soil fertility and associated nitrogen (N) status was a key ecosystem attribute, and surveys of ectomycorrhizal fungal (EMF) communities via epigeous fruiting bodies could provide an effective biotic indicator of forest soil productivity. We explored the utility of aboveground EMF communities in this regard by surveying sporocarps over a 3-year period from contrasting plant associations of southern old-growth boreal forests of British Columbia (Canada). Cumulative richness ranged from 39 to 89 EMF species per plot (0.15 ha) and followed a skewed parabolic correlation with foliar N concentrations and soil N availability. EMF species composition was consistently distinct in ordinations and strongly correlated to the increasing rates of N mineralization aligned with soil productivity. Approximately 40 EMF species were specialists, as they collectively indicated oligotrophic, mesotrophic, and eutrophic nutrient regimes, while the remaining species were categorized as broadly tolerant (distributed over 100% of the N gradient), partially intolerant (approximately 70%), or satellites (rare). The functional organization of EMF communities reflected by distribution classes could help define the ecological integrity of forests, which was characterized in this boreal landscape by an average allotment of 20 broadly tolerant, 25 partially intolerant, 15 specialist, and ten satellite species per plot. Epigeous fruiting bodies provided a disparate yet complementary view to the belowground assessment of EMF communities that was valuable in identifying indicators for ecosystem monitoring.

High diversity of fungi in air particulate matter

Fungal spores can account for large proportions of air particulate matter, and they may potentially influence the hydrological cycle and climate as nuclei for water droplets and ice crystals in clouds, fog, and precipitation. Moreover, some fungi are major pathogens and allergens. The diversity of airborne fungi is, however, not well-known. By DNA analysis we found pronounced differences in the relative abundance and seasonal cycles of various groups of fungi in coarse and fine particulate matter, with more plant pathogens in the coarse fraction and more human pathogens and allergens in the respirable fine particle fraction (<3 microm). Moreover, the ratio of Basidiomycota to Ascomycota was found to be much higher than previously assumed, which might also apply to the biosphere.

Morphological and molecular characterization of Humaria and Genea ectomycorrhizae from Hungarian deciduous forests

The ectomycorrhizae (EM) of Humaria and Genea, two closely related genera of the Pyronemataceae (Ascomycetes), were regularly found in different deciduous forests of Hungary. In the present paper, the morphology and anatomy of these EM are described in detail, including morphometric analyses. Identification of the EM was carried out by molecular taxonomic analyses of the nrDNA ITS sequences obtained from mycorrhizae, herbarium ascomata, and public databases. The anatomy of the EM, examined during this work, was almost identical. They possessed angular outer and epidermoid inner mantle layers and warted, thick-walled emanating hyphae. Ten of our EM sequences grouped into the clade of Humaria hemisphaerica sequences and one into the genus Genea. Both molecular taxonomic analysis and morphometry differentiated three sub-groups within the clade of Humaria, and these methods also clearly separated the EM of Genea from those of Humaria. We may suppose that the previous morphological-anatomical descriptions, lacking molecular taxonomic identification, do not concern the denominated taxa. As a consequence, we stress the importance of revaluating the literature data, based on morphotyping of Humaria and Genea EM, to prevent misidentification in future studies. The presented work demonstrates that combining molecular and morphological analysis is essential for the unambiguous identification of the EM formed by problematic taxa.

Macrofungi diversity in cork-oak and holm-oak forests in Andalusia (southern Spain); an efficient parameter for establishing priorities for its evaluation and conservation

In this work, the fungal diversity of holm-oak and cork-oak woodlands in southern Spain is studied in order to analyse the macrofungi component and its ecological characteristics, as well as to establish priorities for its conservation. For this, we have compiled published as well as unpublished data, and applied compositional analysis and statistical methods (basic statistics, non-parametric and multivariate analyses). Priority areas were selected based on complementarity analysis. As a result, 838 taxa were recorded, 78.6% in cork-oak and 76.4% in holm-oak forests, with 55.1% in common. The ratio of mycorrhizal to saprophitic species indicated that cork-oak woodlands present a higher diversity and conservation degree of its macrofungal community than holm-oak woodlands, since the mycorrhizal component is more important for the conservation of these forests (due to nutritional relations). Both forests types appear well differentiated in the multivariate analysis. In the complementarity analysis, with only one site, we recorded 40% of the total species encountered. The percentage increased to 80% with four sites. This type of approach, by highlighting the important areas for conservation of fungal diversity, constitutes a powerful tool to optimise conservation efforts.

Ectomycorrhizal community structure in a xeric Quercus woodland based on rDNA sequence analysis of sporocarps and pooled roots

Quercus woodlands are key components of California's wild landscapes, yet little is known about ectomycorrhizal (EM) fungi in these ecosystems. We examined the EM community associated with Quercus douglasii using sporocarp surveys and by pooling EM roots and subjecting them to DNA extraction, polymerase chain reaction (PCR), cloning, restriction fragment length polymorphism (RFLP) screening and DNA sequencing. Ectomycorrhizal root symbionts were sampled four times in 2003-04. During this time, the below-ground community structure was relatively stable; we found no evidence of taxa adapted to winter or spring conditions and only one species varied widely in occurrence between years. The EM community from sporocarps and roots was diverse (161 species), rich in Ascomycota (46 species), and dominated by fungi with cryptic sporocarps. This included a large number of resupinate and hypogeous taxa, many of which were detected both above- and below-ground.

High diversity of fungi recovered from the roots of mature tanoak (Lithocarpus densiflorus) in northern California

We collected mature tanoak ( Lithocarpus densiflorus (Hook. & Arn.) Rehder) roots from five stands to characterize the relative abundance and taxonomic richness of root-associated fungi. Fungi were identified using polymerase chain reaction (PCR), cloning, and sequencing of internal transcribed spacer (ITS) and 28S rDNA. A total of 382 cloned PCR inserts were successfully sequenced and then classified into 119 taxa. Of these taxa, 82 were basidiomycetes, 33 were ascomycetes, and 4 were zygomycetes. Thirty-one of the ascomycete sequences were identified as Cenococcum geophilum Fr. with overall richness of 22 ITS types. Other ascomycetes that form mycorrhizal associations were identified including Wilcoxina and Tuber as well as endophytes such as Lachnum , Cadophora , Phialophora , and Phialocephela . The most abundant mycorrhizal groups were Russulaceae ( Lactarius , Macowanites , Russula ) and species in the Thelephorales ( Bankera , Boletopsis , Hydnellum , Tomentella ). Our study demonstrates that tanoak supports a high diversity of ectomycorrhizal fungi with comparable species richness to that observed in Quercus root communities.

Diversity and specificity of ectomycorrhizal fungi retrieved from an old-growth Mediterranean forest dominated by Quercus ilex

We analysed the ectomycorrhizal (ECM) fungal diversity in a Mediterranean old-growth Quercus ilex forest stand from Corsica (France), where Arbutus unedo was the only other ECM host. On a 6400 m2 stand, we investigated whether oak age and host species shaped below-ground ECM diversity. Ectomycorrhizas were collected under Q. ilex individuals of various ages (1 yr seedlings; 3-10 yr saplings; old trees) and A. unedo. They were typed by ITS-RFLP analysis and identified by match to RFLP patterns of fruitbodies, or by sequencing. A diversity of 140 taxa was found among 558 ectomycorrhizas, with many rare taxa. Cenococcum geophilum dominated (35% of ECMs), as well as Russulaceae, Cortinariaceae and Thelephoraceae. Fungal species richness was comparable above and below ground, but the two levels exhibited < 20% overlap in fungal species composition. Quercus ilex age did not strongly shape ECM diversity. The two ECM hosts, A. unedo and Q. ilex, tended to share few ECM species (< 15% of the ECM diversity). Implications for oak forest dynamics are discussed.