Fungal Ecology最新文献

With wildfires reaching unprecedented levels of severity, size and frequency, their impact on soil microbial communities is an important concern. Commencing just weeks following a wildfire in a Douglas-fir-Ponderosa pine forest, we collected surface and mineral soil samples four times over 10 months from four severity levels to better understand the effect of wildfire severity on fungi and their guilds. At medium severity and above, there was a decrease in fungal diversity and a shift in community composition in both layers, while the fungal community from soils burnt by low severity fires remained similar to unburnt soils. Although the richness of putative saprotrophic and pathotrophic fungi in burnt microplots returned to levels comparable to that in the unburnt microplots within weeks of burning, the richness of symbiotrophic, including ectomycorrhizal fungi in burnt plots, did not. The DNA of many putative pyrophilous fungi peaked in estimated abundance within weeks after the fire, even though fruiting was not observed until the following spring.

Index descriptors

pyrophilous fungi; wildfire severity; ITS; metabarcoding; Pseudotsuga menziesii var. glauca; fungal community; disturbance; succession.

We investigated which of the following environmental factors: the number of years since the windthrow of the tree (the age of dead wood), the phytocenosis (the type of forest community), altitude, exposure, wood hardness and the spatial scale of forest disturbances (small gaps with a few fallen spruces vs large-area windthrows) contributed to the diversity and abundance of lichens inhabiting the exposed wood of windthrown spruce trees in Polish Western Carpathian forests. Both Shannon H index and sum of coverage coefficients rose with increasing age of the wood, levelling off after 11–14 y (diversity) and 14–17 y (abundance). This factor appeared to be the most important for this group of lichens, but the significant positive impact of large-area windthrows on the lichen abundance was also demonstrated by using a GLM model. The age of the wood we precisely determined on the basis of data on Norway spruce mortality collected annually in permanent plots of the Gorce National Park since 2000. Using the Shore durometer we linked the course of the wood-inhabiting lichen succession with wood decay more precisely than before. The largest number of species was associated with medium hard wood, i.e., 51 < x ≤ 80 on the Shore scale. Based on the NMDS analysis, we distinguished four age groups of logs, differing in lichen abundance and defined by the dominance of distinctive species. A large number of usually corticolous lichen species used the wood of windthrown spruce logs as an optional habitat to survive large-scale, post-hurricane forest disturbances.

Knoxdaviesia and Sporothrix species occupy the flower heads of some Protea plants in southern Africa. Knoxdaviesia species display exceptional genetic diversity within the Core Cape Subregion (CCR) and are readily dispersed across large distances. This study aimed to determine whether overlapping ecologies have led to a similar population genetic structure in Sporothrix splendens. Two DNA sequence markers, β-tubulin and a microsatellite region, were amplified in 97 S. splendens strains from eight populations that span its host distribution. Genetic diversity was low in a geographically isolated population, but high elsewhere. CCR populations were closely related, showing isolation by distance with populations at the eastern edge of the sampling range. Like Knoxdaviesia species, long-distance dispersal of S. splendens spores is prevalent, although likely affected by patchy host populations. This study is the first to consider populations of a non-clinical Sporothrix species, providing insights into the population attributes of a naturally distributed species.

Endophytic fungi occur in living tissues of terrestrial plants. Many of these fungi are primarily biotrophic, but the trophic range of endophytic fungi as a group may not be fully appreciated. In this study, our goals were (1) for the Class 3 foliar endophytic fungi isolated from Quercus gambelii, determine their potential saprotrophic capacity, which we define as the difference in growth rate in culture on Quercus gambelii leaf litter medium and control medium lacking leaf litter and (2) quantify sources of variation among isolates of these endophytic fungi in potential saprotrophic capacity, including variation due to microsite within host trees (leaves receiving full sun vs. shade) and variation within and among fungal genera. We found that 48 of the 49 tested endophytic fungal isolates have significant potential saprotrophic capacity. Contrary to expectation, the amount of solar radiation available to the leaf from which the fungi were isolated had no significant impact on potential saprotrophic capacity and there was more variability in potential saprotrophic capacity among isolates within a genus than among genera. Our results suggest that some Class 3 endophytic fungi may have the potential to function as saprotrophic fungi within plant litter, but this remains to be seen for these Quercus gambelii isolates under more natural circumstances.

Aquatic hyphomycetes are microbial decomposers in freshwater environments that, together with detritivores, play an essential role in the functioning of low-order streams. Here, we evaluated aquatic hyphomycetes communities associated with decomposing leaves of Nectandra megapotamica, a common Neotropical riparian tree, along a subtropical-tropical latitudinal gradient. Two forest streams located in subtropical regions and 3 in tropical regions were selected. We identified 29 species of aquatic hyphomycetes, 22 (75.8%) in subtropical streams and 15 (51.7%) in tropical streams. We also found a higher fungal biomass in subtropical streams. However, the amounts of leaf mass loss did not differ between regions, but the values were higher in summer than in winter. High temperature, pH and electrical conductivity values, as well as low dissolved oxygen levels, negatively affected spore production. These results suggest that the subtropical-tropical gradient is an important predictor of aquatic hyphomycete diversity; however, the observed species had different sensitivities to local environmental factors.

Decomposition transfers carbon (C) from detrital organic matter to soil and atmospheric pools. In forested ecosystems, deadwood accounts for a large proportion of the detrital C pool and is primarily decomposed by wood-inhabiting fungi (WIF). Deadwood reductions linked to forest harvesting may alter WIF richness and composition, thus indirectly influencing the persistence of deadwood and its contribution to C and nutrient cycling. Forest structure was enhanced via canopy gap creation and coarse woody debris (CWD) addition that mimic natural disturbance by windfall within a deciduous northern hardwood forest (Wisconsin, USA) to examine its effect on deadwood-associated biodiversity and function. Experimental sugar maple (Acer saccharum) logs were sampled, for DNA extraction, ten years after placement to determine the assembly of fungal community composition and its relationship to wood decay rates.

Our findings suggest that the WIF community responded to gap disturbance by favoring species able to persist under more extreme microclimates caused by gaps. CWD addition under closed canopy tended to favor a different species assemblage from gap creation treatments and the control, where canopy was undisturbed and CWD was not added. This was presumably due to consistent microclimatic conditions and the abundance of CWD substrates for host specialists. Fungal OTU richness was significantly and inversely related to CWD decay rates, likely due to competition for resources. In contrast, fungal OTU composition was not significantly related to CWD decay rates, canopy openness or CWD addition amounts. Our study site represents a diverse fungal community in which complex interactions among wood-inhabiting organisms and abiotic factors are likely to slow CWD decomposition, which suggests that maintaining a biodiverse and microsite-rich ecosystem may enhance the capacity for C storage within temperate forests.

This study investigated broad patterns in communities of ectomycorrhizal fungi from three Florida habitats (sandhills, scrub, and pine rocklands) and the ability of spore bank fungi to associate with Pinus elliottii (slash pine) and Pinus densa (south Florida slash pine). Efforts to replant pines in the endangered pine rocklands are vital to the persistence of this habitat, yet little is known about the ectomycorrhizal fungi communities or how they may differ from those in other pine-dominated habitats in Florida. We used high-throughput amplicon sequencing (HTS) to assess baseline fungal communities and greenhouse bioassays to bait ectomycorrhizal fungi using seedlings. HTS soil data recovered 188 ectomycorrhizal species but only a few subsequently colonized the bioassay seedlings. We recovered 21 ectomycorrhizal species on pine seedlings including common spore bank fungi such as Cenococcum, Suillus, and Tuber, but Rhizopogon species were dominant across all sites and habitats. Habitat type and site were significant variables influencing the community composition of the total soil fungal community, soil ectomycorrhizal community, and the fungi found on seedling root tips. However, we found no significant differences between the ectomycorrhizal communities on seedling roots from the two Pinus species.

Ongoing climate change in the boreal forests of western North America is associated with wildfires which are increasing in extent and severity, thus impacting mycorrhizal fungal communities through fungal mortality and shifts in host species and age. We planted three native tree species, Picea mariana, Picea glauca, and Populous tremuloides, and non-native Pinus contorta var. latifolia at 22 post-fire sites, encompassing wide variation in fire severity and environmental gradients, across Interior Alaska. We characterized fungal community composition using Illumina MiSeq. Fire severity had a greater impact on fungal composition than the environmental variables we considered. There were large shifts in fungal Phyla and guilds with high severity, but these shifts were dependent on host tree species. We also found pine-specific fungi on Pinus contorta var. latifolia. These data suggest that shifts in mycorrhizal fungal communities from increases in fire severity may be exacerbated by associated changes in plant successional trajectories and host composition.

Leaf-cutting ants interact naturally with a range of antagonistic microorganisms, among them the soil-borne fungus Syncephalastrum. The antagonism of this fungus to the leaf-cutting ants’ fungal cultivar has been shown in studies without the ant queens. So far, the impacts of this fungus on whole colonies (queenright) of leaf-cutting ants are unknown. We assessed the impacts of Syncephalastrum on queenless and queenright colonies of Acromyrmex subterraneus subterraneus. In general, Syncephalastrum negatively impacted leaf cutting but not midden production or colony weight. This impact was greater in queenless colonies. Nevertheless, it did not compromise the survival of any colony. This indicates that the virulence of this fungus to leaf-cutting ant colonies may be limited in a more realistic set-up than previously reported. We propose that future laboratory studies also use queenright colonies where possible, and that the diverse species of leaf-cutting ants also be considered.

Foliar fungal endophytes are horizontally transmitted symbionts that inhabit healthy, photosynthetic tissues of all lineages of land plants where they influence plant health and productivity. Endophyte communities often are more similar among closely related hosts, potentially as a result of a preference for particular morphological, ecophysiological, or chemical host traits. However, the various ecological and evolutionary factors that drive community assembly often are difficult to disentangle. Here, we examined the impact of six polyphenolic compounds on the growth of 15 phylogenetically diverse Quercus (oak)-associated fungal species and assessed whether tolerance to phenolics is associated with their degree of specialization to oaks in nature. Despite frequently reported antifungal properties of phenolics, we found that oak-associated fungi grew the same or better than positive controls in 78% of trials with all compounds, although fungal sensitivity differed as a function of compound type and concentration. Overall, species with high specificity to Quercus had the greatest tolerance to phenolics, whereas generalists were more sensitive. Differences between generalists and specialists suggest that variation in phenolic abundance and composition among oaks may act as a selective filter that influences endophyte host associations in nature.