Patterns in Ectomycorrhizal Diversity, Community Composition, and Exploration Types in European Beech, Pine, and Spruce Forests

Interspecific selection in a diverse mycorrhizal symbiosis

Coevolution describes evolutionary change in which two or more interacting species reciprocally drive each other's evolution, potentially resulting in trait diversification and ecological speciation. Much progress has been made in analysis of its dynamics and consequences, but relatively little is understood about how coevolution works in multispecies interactions, i.e., those with diverse suites of species on one or both sides of an interaction. Interactions among plant hosts and their mutualistic ectomycorrhizal fungi (ECM) may provide an ecologically unique arena to examine the nature of selection in multispecies interactions. Using native genotypes of Monterey pine (Pinus radiata), we performed a common garden experiment at a field site that contains native stands to investigate selection from ECM fungi on pine traits. We planted seedlings from all five native populations, as well as inter-population crosses to represent intermediate phenotypes/genotypes, and measured seedling traits and ECM fungal traits to evaluate the potential for evolution in the symbiosis. We then combined field estimates of selection gradients with estimates of heritability and genetic variance-covariance matrices for multiple traits of the mutualism to determine which fungal traits drive plant fitness variation. We found evidence that certain fungal operational taxonomic units, families and species-level morphological traits by which ECM fungi acquire and transport nutrients exert selection on plant traits related to growth and allocation patterns. This work represents the first field-based, community-level study measuring multispecific coevolutionary selection in nutritional symbioses.

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

Background

The cultivation of short-rotation tree species on non-forest land is increasing due to the growing demand for woody biomass for the future bioeconomy and to mitigate climate change impacts. However, forest plantations are often seen as a trade-off between climate benefits and low biodiversity. The diversity and composition of soil fungal biota in plantations of hybrid aspen, one of the most planted tree species for short-rotation forestry in Northern Europe, are poorly studied.

Methods

The goal of this study was to obtain baseline knowledge about the soil fungal biota and the edaphic, floristic and management factors that drive fungal richness and communities in 18-year-old hybrid aspen plantations on former agricultural soils and compare the fungal biota with those of European aspen stands on native forest land in a 130-year chronosequence. Sites were categorized as hybrid aspen (17-18-year-old plantations) and native aspen stands of three age classes (8-29, 30-55, and 65-131-year-old stands). High-throughput sequencing was applied to soil samples to investigate fungal diversity and assemblages.

Results

Native aspen forests showed a higher ectomycorrhizal (EcM) fungal OTU richness than plantations, regardless of forest age. Short-distance type EcM genera dominated in both plantations and forests. The richness of saprotrophic fungi was similar between native forest and plantation sites and was highest in the middle-aged class (30-55-year-old stands) in the native aspen stands. The fungal communities of native forests and plantations were significantly different. Community composition varied more, and the natural forest sites were more diverse than the relatively homogeneous plantations. Soil pH was the best explanatory variable to describe soil fungal communities in hybrid aspen stands. Soil fungal community composition did not show any clear patterns between the age classes of native aspen stands.

Conclusion

We conclude that edaphic factors are more important in describing fungal communities in both native aspen forest sites and hybrid aspen plantation sites than forest thinning, age, or former land use for plantations. Although first-generation hybrid aspen plantations and native forests are similar in overall fungal diversity, their taxonomic and functional composition is strikingly different. Therefore, hybrid aspen plantations can be used to reduce felling pressure on native forests; however, our knowledge is still insufficient to conclude that plantations could replace native aspen forests from the soil biodiversity perspective.

The Ectomycorrhizal Fungi and Soil Bacterial Communities of the Five Typical Tree Species in the Junzifeng National Nature Reserve, Southeast China

To explore the contribution of microorganisms to forest ecosystem function, we studied the ectomycorrhizal (ECM) fungal and soil bacterial community of the five typical tree species (Pinus massoniana, PM; Castanopsis carlesii, CC; Castanopsis eyrei, CE; Castanopsis fargesii, CF; and Keteleeria cyclolepis, KC) at the Junzifeng National Nature Reserve. The results indicated that the ECM fungal and soil bacterial diversity of CC and CF was similar, and the diversity rates of CC and CF were higher than those of PM, CE, and KC. Cenococcum geophilum and unclassified_Cortinariaceae II were the most prevalent occurring ECM fungi species in the five typical tree species, followed by unclassified_Cortinariaceae I and Lactarius atrofuscus. In bacteria, the dominant bacterial genera were Acidothermus, Bradyrhizobium, Acidibacter, Candidatus_Solibacter, Candidatus_Koribacter, Roseiarcus, and Bryobacter. EMF fungi and soil bacteria were correlated with edaphic factors, especially the soil pH, TP, and TK, caused by stand development. The results show that the community characteristics of ECM fungi and bacteria in the typical tree species of the Junzifeng National Nature Reserve reflect the critical role of soil microorganisms in stabilizing forest ecosystems.

Ectomycorrhizal community associated with Cedrus deodara in four urban forests of Nantong in East China

Ectomycorrhizal (ECM) fungi play fundamental roles in host plant growth and terrestrial ecosystems. Cedrus deodara is cultivated in several regions in China, has high ecological, economic and medicinal value, for its afforestation and providing timber and wood oil. Here, we investigated ECM colonization status of four urban C. deodara forests in Nantong, East China. We also characterized soil spore banks by conducting bioassay experiments using soils collected from these forests. In total, we identified 19 ECM fungal species, of which 13 species were found in mature forests and 9 species were identified in bioassay experiments, with only 3 species shared. Soil pH and available P content had significant effects on species occurrence in both mature trees and bioassay seedlings on local scales. ECM communities clearly (A = 0.391, p = 0.006) separated mature forests from spore banks. Thelephoracae was the richest family we detected associated with C. deodara, while Trichophaea sp. was the most dominant in mature forests, and Wilcoxina sp. was dominant in spore banks. ECM richness affected the growth of bioassay seedlings, especially after inoculation with 2 ECM species, promoting root growth, significantly (F = 3.028, p = 0.050), but it had no effects on shoots (F = 1.778, p = 0.177). No effect of inoculation rate was found on seedlings growth. To conserve this important tree species, the ECM fungi that are associated with it should be considered.

Ectomycorrhizal Community Shifts at a Former Uranium Mining Site

Ectomycorrhizal communities at young oak, pine, and birch stands in a former uranium mining site showed a low diversity of morphotypes with a preference for contact and short-distance exploration strategies formed by the fungi Russulaceae, Inocybaceae, Cortinariaceae, Thelephoraceae, Rhizopogonaceae, Tricholomataceae, as well as abundant Meliniomyces bicolor. In order to have better control over abiotic conditions, we established pot experiments with re-potted trees taken from the sites of direct investigation. This more standardized cultivation resulted in a lower diversity and decreased prominence of M. bicolor. In addition, the exploration strategies shifted to include long-distance exploration types. To mimic secondary succession with a high prevalence of fungal propagules present in the soil, inoculation of re-potted trees observed under standardized conditions for two years was used. The super-inoculation increased the effect of lower abundance and diversity of morphotypes. The contact morphotypes correlated with high Al, Cu, Fe, Sr, and U soil contents, the dark-colored short-distance exploration type did not show a specific preference for soil characteristics, and the medium fringe type with rhizomorphs on oaks correlated with total nitrogen. Thus, we could demonstrate that field trees, in a species-dependent manner, selected for ectomycorrhizal fungi with exploration types are likely to improve the plant's tolerance to specific abiotic conditions.

Characterization of ectomycorrhizal fungal communities associated with tree species on an iron tailings deposit undergoing restoration

Vegetation restoration is an effective method to improve the ecological environment of mine tailings, which has a profound impact on the potential ecological functions of soil fungal communities; yet, little is known about its beneficial effect on soil ectomycorrhizal fungal community. In this study, the responses of soil characteristics and soil ectomycorrhizal fungal community diversity and structure to different revegetation, as well as the contribution of soil factors to soil ectomycorrhizal community were investigated in Liaoning Province, China. As we anticipated, the presence of vegetation significantly improved most soil properties we studied. What's more, compared to Korean pine (Pinus koraiensis Sieb. et Zucc.), Chinese poplar (Populus simonii Carr), and black locust (Robinia pseudoacacia L) could better improve soil total carbon, total nitrogen, total phosphorus, and available phosphorus. In addition, soil ectomycorrhizal fungal community diversity in black locust was greater than Korean pine and Populus simonii. Nonmetric multidimensional scaling analyses indicated that soil ectomycorrhizal community significantly differed depending on different revegetation types. Thus, these results indicated that black locust could be a suitable species for the revegetation of iron mine tailings. The study provided theoretical basis for ecological restoration of iron mine tailings using local plant species.

Abiotic environmental factors drive the diversity, compositional dynamics and habitat preference of ectomycorrhizal fungi in Pannonian forest types

Ectomycorrhizal (ECM) fungi are among the most diverse and dominant fungal groups in temperate forests and are crucial for ecosystem functioning of forests and their resilience toward disturbance. We carried out DNA metabarcoding of ECM fungi from soil samples taken at 62 sites in the Bükk Mountains in northern Hungary. The selected sampling sites represent the characteristic Pannonian forest types distributed along elevation (i.e., temperature), pH and slope aspect gradients. We compared richness and community composition of ECM fungi among forest types and explored relationships among environmental variables and ECM fungal alpha and beta diversity. The DNA sequence data generated in this study indicated strong correlations between fungal community composition and environmental variables, particularly with pH and soil moisture, with many ECM fungi showing preference for specific zonal, topographic or edaphic forest types. Several ECM fungal genera showed significant differences in richness among forest types and exhibited strong compositional differences mostly driven by differences in environmental factors. Despite the relatively high proportions of compositional variance explained by the tested environmental variables, a large proportion of the compositional variance remained unexplained, indicating that both niche (environmental filtering) and neutral (stochastic) processes shape ECM fungal community composition at landscape level. Our work provides unprecedented insights into the diversity, landscape-level distribution, and habitat preferences of ECM fungi in the Pannonian forests of Northern Hungary.

Soil nutrients and plant diversity affect ectomycorrhizal fungal community structure and functional traits across three subalpine coniferous forests

The symbiotic relationship between ectomycorrhizal fungi (EMF) and the roots of host plants is significantly important in regulating the health and stability of ecosystems, especially of those such as the climate warming affected subalpine forest ecosystems. Therefore, from the coniferous forest systems located in the Southern Qinghai-Tibetan Plateau, root tips from three forest tree species: Pinus wallichiana, Abies spectabilis and Picea spinulosa, were collected to look for the local causes of EMF community composition and diversity patterns. The EMF colonization rate, diversity and taxonomic community structure were determined by morphotyping and sanger sequencing of the fungal ITS gene from the root tip samples. Soil exploration types were identified based on the morphologies of the ectomycorrhizas, coupled with soil properties analysis and plant diversity survey. Contrasting patterns of EMF community and functional diversity were found across the studied three forests types dominated by different coniferous tree species. In terms of associations between soil and EMF properties, the total phosphorus (TP) and nitrate (NO₃⁻) contents in soil negatively correlated with the colonization rate and the Shannon diversity index of EMF in contrast to the positive relationship between TP and EMF richness. The soil total nitrogen (TN), ammonium (NH₄⁺) and plant diversity together caused 57.6% of the total variations in the EMF taxonomic community structure at the three investigated forest systems. Whereas based on the soil exploration types alone, NH₄⁺ and TN explained 74.2% of variance in the EMF community structures. Overall, the findings of this study leverage our understanding of EMF dynamics and local influencing factors in coniferous forests dominated by different tree species within the subalpine climatic zone.

Communities of Mycorrhizal Fungi among Seedlings of Scots Pine (Pinus sylvestris L.) Growing on a Clearcut in Microsites Generated by Different Site-Preparation Methods

In European forests, the Scots pine (Pinus sylvestris L.) most often regenerates on clearcuts, following mechanical site preparation. Both of these silvicultural treatments (the removal of trees and preparation) have an impact on soil properties, and on the mycorrhizal fungi associated with the roots of seedlings. We therefore compared assemblages of mycorrhizal fungi associating with natural-regeneration pine seedlings growing on a clearcut, in relation to six types of microsite created using three mechanical site-preparation tools, i.e., a double-mouldboard forest plough (creating furrow and ridge), an active single-disc plough (establishing another type of furrow and ridge), and a forest mill—developing strips, as well as a non-mechanical site preparation control. A total of 46 taxa of mycorrhizal fungi were detected, with Wilcoxina mikolae being the most abundant species (relative abundance—79.8%), and the one occurring most frequently (96.8%). Other abundant mycorrhizal fungi were Thelephora terrestris (3.8%), Tylospora asterophora (3.2%), Hyaloscypha bicolor (2.2%), and Cenococcum geophilum (1.7%). The roots of seedlings growing in the non-mechanical site preparation control were characterised by a significantly greater presence of mycorrhizal root tips, compared with the roots of seedlings growing at other microsites. The highest percentage of non-mycorrhizal root tips was present on pines growing on the two types of ridge: the microsites which characterized the highest levels of mineral nutrients. Communities of mycorrhizal fungi differed between microsites. The five microsites: both types of furrow, forest plough ridge, forest mill strip, and non-mechanical site preparation control, were not found to differ from each other, but did differ from the active plough ridge treatment. The highest diversity of mycorrhizal fungi (Shannon–Wiener and Simpson indexes) was in the non-mechanical site preparation control. Any method of mechanical site preparation in the clearcut decreases the level of root mycorrhization and the biodiversity of mycorrhizal fungi. The least suitable method from the point of view of mycorrhizal fungal communities is the use of an active plough.

Predictors of taxonomic and functional composition of black spruce seedling ectomycorrhizal fungal communities along peatland drainage gradients

Many trees depend on symbiotic ectomycorrhizal fungi for nutrients in exchange for photosynthetically derived carbohydrates. Trees growing in peatlands, which cover 3% of the earth's terrestrial surface area yet hold approximately one-third of organic soil carbon stocks, may benefit from ectomycorrhizal fungi that can efficiently forage for nutrients and degrade organic matter using oxidative enzymes such as class II peroxidases. However, such traits may place a higher carbon cost on both the fungi and host tree. To investigate these trade-offs that might structure peatland ectomycorrhizal fungal communities, we sampled black spruce (Picea mariana (Mill.)) seedlings along 100-year-old peatland drainage gradients in Minnesota, USA, that had resulted in higher soil nitrogen and canopy density. Structural equation models revealed that the relative abundance of the dominant ectomycorrhizal fungal genus, Cortinarius, which is known for relatively high fungal biomass coupled with elevated class II peroxidase potential, was negatively linked to site fertility but more positively affected by recent host stem radial growth, suggesting carbon limitation. In contrast, Cenococcum, known for comparatively lower fungal biomass and less class II peroxidase potential, was negatively linked to host stem radial growth and unrelated to site fertility. Like Cortinarius, the estimated relative abundance of class II peroxidase genes in the ectomycorrhizal community was more related to host stem radial growth than site fertility. Our findings indicate a trade-off between symbiont foraging traits and associated carbon costs that consequently structure seedling ectomycorrhizal fungal communities in peatlands.

Localized reshaping of the fungal community in response to a forest fungal pathogen reveals resilience of Mediterranean mycobiota

Mediterranean forests are facing the impact of pests such as the soilborne Phytophthora cambivora, the causal agent of Ink disease, and this impact is made more severe by global changes. The status and resilience of the soil microbial ecosystem in areas with such a disturbance are little known; however, the assessment of the microbial community is fundamental to preserve the ecosystem functioning under emerging challenges. We profile soil fungal communities in a chestnut stand affected by ink disease in Italy using metabarcoding, and couple high-throughput sequencing with physico-chemical parameters and dendrometric measurements. Since the site also includes an area where the disease symptoms seem to be suppressed, we performed several analyses to search for determinants that may contribute to such difference. We demonstrate that neither pathogen presence nor trees decline associate with the reduction of the residing community diversity and functions, but rather with microbial network reshaping through substitutions and new interactions, despite a conservation of core taxa. We predict interactions between taxa and parameters such as soil pH and C/N ratio, and suggest that disease incidence may also relate with disappearance of pathogen antagonists, including ericoid- and ectomycorrhizal (ECM) fungi. By combining metabarcoding and field studies, we infer the resilient status of the fungal community towards a biotic stressor, and provide a benchmark for the study of other threatened ecosystems.

High Fungal Diversity but Low Seasonal Dynamics and Ectomycorrhizal Abundance in a Mountain Beech Forest

Forests on steep slopes constitute a significant proportion of European mountain areas and are important as production and protection forests. This study describes the soil fungal community structure in a European beech-dominated mountain forest stands in the Northern Calcareous Alps and investigates how it is determined by season and soil properties. Samples were collected at high spatial resolution in an area of ca. 100 m × 700 m in May (spring) and August (summer). Illumina MiSeq high-throughput sequencing of the ITS2-region revealed distinct patterns for the soil fungal communities. In contrast to other studies from temperate European beech forest stands, Ascomycota dominated the highly diverse fungal community, while ectomycorrhizal fungi were of lower abundance. Russulaceae, which are often among the dominant ectomycorrhizal fungi associated with European beech, were absent from all samples. Potentially plant pathogenic fungi were more prevalent than previously reported. Only subtle seasonal differences were found between fungal communities in spring and summer. Especially, dominant saprotrophic taxa were largely unaffected by season, while slightly stronger effects were observed for ectomycorrhizal fungi. Soil characteristics like pH and organic carbon content, on the other hand, strongly shaped abundant taxa among the saprotrophic fungal community.

Management After Windstorm Affects the Composition of Ectomycorrhizal Symbionts of Regenerating Trees but Not Their Mycorrhizal Networks

Due to ongoing climate change, forests are expected to face significant disturbances more frequently than in the past. Appropriate management is intended to facilitate forest regeneration. Because European temperate forests mostly consist of trees associated with ectomycorrhizal (ECM) fungi, understanding their role in these disturbances is important to develop strategies to minimize their consequences and effectively restore forests. Our aim was to determine how traditional (EXT) and nonintervention (NEX) management in originally Norway spruce (Picea abies) forests with an admixture of European larch (Larix decidua) affect ECM fungal communities and the potential to interconnect different tree species via ECM networks 15 years after a windstorm. Ten plots in NEX and 10 plots in EXT with the co-occurrences of Norway spruce, European larch, and silver birch (Betula pendula) were selected, and a total of 57 ECM taxa were identified using ITS sequencing from ECM root tips. In both treatments, five ECM species associated with all the studied tree species dominated, with a total abundance of approximately 50% in the examined root samples. Because there were no significant differences between treatments in the number of ECM species associated with different tree species combinations in individual plots, we concluded that the management type did not have a significant effect on networking. However, management significantly affected the compositions of ECM symbionts of Norway spruce and European larch but not those of silver birch. Although this result is explained by the occurrence of seedlings and ECM propagules that were present in the original forest, the consequences are difficult to assess without knowledge of the ecology of different ECM symbionts.

Nutrient trade-offs mediated by ectomycorrhizal strategies in plants: Evidence from an Abies species in subalpine forests

Ectomycorrhizal (ECM) symbiosis is an evolutionary biological trait of higher plants for effective nutrient uptakes. However, little is known that how the formation and morphological differentiations of ECM roots mediate the nutrients of below- and aboveground plant tissues and the balance among nutrient elements across environmental gradients. Here, we investigated the effects of ECM foraging strategies on root and foliar N and P concentrations and N:P ratio Abies faxoniana under variations of climate and soil conditions.The ECM symbionts preferentially mediated P uptake under both N and P limitations. The uptake efficiency of N and P was primarily associated with the ECM root traits, for example, ECM root tip density, superficial area of ECM root tips, and the ratio of living to dead root tips, and was affected by the ECM proliferations and morphological differentiations. The tissue N and P concentrations were positively associated with the abundance of the contact exploration type and negatively with that of the short-distance exploration type.Our findings indicate that the nutritional status of both below- and aboveground plant tissues can be strongly affected by ECM symbiosis in natural environments. Variations in the ECM strategies in response to varying environmental conditions significantly influence plant nutrient uptakes and trade-offs.

Fungal ethnoecology: observed habitat preferences and the perception of changes in fungal abundance by mushroom collectors in Poland

BACKGROUND

Scientists frequently raise the topic of data deficiency related to the abundance and distribution of macrofungi in the context of climate change. Our study is the first detailed documentation on locals' perception of fungal ecology which covers a large mycophilous region of Europe (Mazovia, Poland).

METHODS

A total of 695 semi-structured interviews were carried out among local informants in 38 localities proportionally distributed throughout the study area (one locality approximately every 30 km). Interview questions concerned fungi species collected, their perceived habitats, and whether any changes had been noted in their abundance. As many as 556 respondents provided information concerning fungal ecology. In these descriptions, 35 taxa were mentioned by at least 5 respondents.

RESULTS

The data collected during interviews allowed us to create collective folk descriptions of habitat preferences and a list of 98 different macro-, meso-, and microhabitats of macrofungi described by the respondents. This list of recurring habitats assigned to particular macrofungal taxa coincides with, and sometimes exceeds, data available in scientific publications. Some habitat preferences observed by the informants have not yet been researched or tested by science. Out of 695 respondents, 366 (53%) noticed a steady decrease in local macrofungi abundance, and only one person claimed to have observed a steady increase. Imleria badia was the only species with increased abundance, as noted by fifteen independent respondents. The main listed reason for abundance decrease was drought (f = 186).

CONCLUSIONS

Collected information on the ecology of fungi shows that local knowledge does not generally diverge from scientific knowledge. The acquired information related to macrofungal abundance and ecology may also be used as a tool for the formulation of new scientific questions and theories. The analysis of local fungi observations might contribute to broadening knowledge about local changes in fungi and enable new estimations related to large-scale analysis of macrofungal abundance.

Ectomycorrhizal community composition of organic and mineral soil horizons in silver fir (Abies alba Mill.) stands

Vertical ectomycorrhizal (ECM) community composition was assessed on silver fir (Abies alba Mill.) in beech-silver fir forests in Bosnia and Herzegovina. Organic and upper mineral horizons were described by pedological analyses. Silver fir root tips were divided into vital ECM, old and non-mycorrhizal for each horizon separately. Morpho-anatomical classification of vital ECM root tips with an assessment of abundance was followed by ITS-based molecular characterization and classification into exploration types. The percentage of vital ECM root tips was not affected by the soil horizon. Altogether, 40 ECM taxa were recorded. Several taxa have not previously been reported for silver fir: Hebeloma laterinum, Inocybe fuscidula, I. glabripes, Lactarius acris, L. albocarneus, L. blennius, L. fluens, Ramaria bataillei, Russula badia, R. lutea, R. mairei, Sistotrema sp., Tarzetta catinus, Tomentella atroarenicolor, T. badia, T. cinerascens, T. bryophylla, and T. ramosissima, indicating high potential for diversity of ECM fungi in silver fir stands. No significant differences in community composition and species richness and diversity were detected between mineral and organic horizons. Community composition was affected by CaCO₃, organic carbon concentration, organic carbon stock, total nitrogen stock, C/N ratio and soil bulk density. No significant effects of soil parameters were detected for exploration types. The contact exploration type was dominant in both soil horizons. Significantly different relative abundances of dominant taxa Tomentella stuposa, Cenococcum geophilum and Piloderma sp. 1 were detected in the two horizons. Twelve taxa were limited to the organic horizon and eight to the mineral horizon.

Drivers of Ectomycorrhizal Fungal Community Structure Associated with Pinus sylvestris var. mongolica Differ at Regional vs. Local Spatial Scales in Northern China

Pinus sylvestris var. mongolica, a widely planted tree species, is facing long-lasting, unresolved degradation in desertified Northern China. Ectomycorrhizal fungi (EMF) are closely related to the stand status, because they substantially participate in ecological processes of terrestrial forest ecosystems. EMF may be key to solving the introduction recession. Therefore, we performed DNA sequencing of P. sylvestris root samples from plantations and natural forests as control to characterize the EMF from semi-arid and dry sub-humid regions, using ITS Illumina sequencing and conventional soil physicochemical index determination. The results indicated that (1) the dominant EMF genera were Suillus, Rhizopogon, and Wilcoxina in the Hulunbuir, Mu Us, and Horqin Sandy Lands, respectively. Their dominance retained with stand ageing. (2) Plantation EM fungal diversity differs significantly among the three sandy lands and was significantly lower than in natural forest. The diversity varied with stand age, showing distinct trends at the local scale. (3) At the regional scale, the mean annual sunshine times and the soil organic carbon content affect EMF diversity. The community composition and structure were more characterized by temperature and precipitation. At the local scale, besides the soil organic carbon content, the EM fungal community composition and structure were correlated with total nitrogen and phosphorus content (Hulunbuir), the total phosphorus content (Mu Us), and the pH and total soil porosity (Horqin). The EM fungal community composition and structure have the obvious geographical distribution variation; they were strongly correlated with the meteorological elements and soil nutrients at the regional scale. At the local scale, they were jointly driven by stand age and soil properties. This improved information contributes to increasing the understanding of the interaction between EMF and forest ecosystems and guides sustainable forest management of degraded P. sylvestris plantations.

Soil Nematode Fauna and Microbial Characteristics in an Early-Successional Forest Ecosystem

Windstorms can often decrease the diversity of native local biota in European forests. The effects of windstorms on the species richness of flora and fauna in coniferous forests of natural reserves are well established, but the effects on biotas in productive deciduous forests have been less well studied. We analyzed the impact of windstorms on the diversity and abundance of soil nematode communities and microbial activity and their relationships with the succession of plant species and basic soil physicochemical properties 12 and 36 months after a windstorm in Fagus sylvatica forests. The relationships were investigated in cleared early-successional forest ecosystems and at undamaged forest sites as a control. The windstorm significantly affected total nematode abundance, number of nematode species, and the diversity and abundance of all nematode functional guilds, but no functional guilds disappeared after the disturbance. The abundance of several nematode taxa but not total nematode abundance was positively correlated with soil-moisture content. Indices of the nematode communities were inconsistent between sites due to their variable ability to identify ecosystem disturbance 12 months after the storm. In contrast, the metabolic activity of various functional groups identified ecosystem disturbance well throughout the study. Positive correlations were identified between the number of plant parasites and soil-moisture content and between carnivore abundance and soil pH. Positive mutual links of some nematode genera (mainly plant parasites) with the distribution of dominant grasses and herbs depended on the habitat. In contrast, microbial activity differed significantly between disturbed and undisturbed sites up to 36 months after the storm, especially soil basal respiration, N mineralization, and microbial biomass. Our results indicated different temporal responses for two groups of soil organisms to the destruction of the tree canopy. Soil nematodes reacted immediately, but changes in the microbial communities were visible much later after the disturbance.

Ectomycorrhizal Community on Norway Spruce Seedlings Following Bark Beetle Infestation

Ectomycorrhizal (ECM) fungi importantly influence seedling growth, nutrition, and survival and create an extensive mycelial network interconnecting tree species and enabling resource redistribution. Due to their symbiotic relationship with trees, they are impacted by forest disturbances, which are of increasing relevance due to climate change. The effect of disturbance on seedling colonization and their morphology is still largely unknown. Seedling growth parameters and the ECM fungal assemblage on the roots of Norway spruce (Picea abies (L.) H. Karst.) seedlings were assessed in mature spruce forests attacked and destroyed by bark beetle and in a mature non-attacked forest as a reference. We did not detect significant differences in number of ECM species on seedling roots among forest types, but ECM species composition changed; Tylospora fibrillosa (Burt) Donk, Meliniomyces variabilis Hambl. & Sigler, and Phialocephala fortinii C.J.K. Wang & H.E. Wilcox were characteristic species in the forest destroyed by bark beetle, whereas Lactarius, Cortinarius, and Russula were in the mature forest. Forest type further significantly influenced the height, root length, and root collar thickness of seedlings and the proportion of exploration types of mycorrhizae.

Shifts in Ectomycorrhizal Fungal Communities and Exploration Types Relate to the Environment and Fine-Root Traits Across Interior Douglas-Fir Forests of Western Canada

Large-scale studies that examine the responses of ectomycorrhizal fungi across biogeographic gradients are necessary to assess their role in mediating current and predicted future alterations in forest ecosystem processes. We assessed the extent of environmental filtering on interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) ectomycorrhizal fungal communities across regional gradients in precipitation, temperature, and soil fertility in interior Douglas-fir dominated forests of western Canada. We also examined relationships between fine-root traits and mycorrhizal fungal exploration types by combining root and fungal trait measurements with next-generation sequencing. Temperature, precipitation, and soil C:N ratio affected fungal community dissimilarity and exploration type abundance but had no effect on α-diversity. Fungi with rhizomorphs (e.g., Piloderma sp.) or proteolytic abilities (e.g., Cortinarius sp.) dominated communities in warmer and less fertile environments. Ascomycetes (e.g., Cenococcum geophilum) or shorter distance explorers, which potentially cost the plant less C, were favored in colder/drier climates where soils were richer in total nitrogen. Environmental filtering of ectomycorrhizal fungal communities is potentially related to co-evolutionary history between Douglas-fir populations and fungal symbionts, suggesting success of interior Douglas-fir as climate changes may be dependent on maintaining strong associations with local communities of mycorrhizal fungi. No evidence for a link between root and fungal resource foraging strategies was found at the regional scale. This lack of evidence further supports the need for a mycorrhizal symbiosis framework that is independent of root trait frameworks, to aid in understanding belowground plant uptake strategies across environments.