Thomas D. Bruns's research while affiliated with University of California, Berkeley and other places

Publications (46)

Article
Wildfires drastically impact the soil environment altering the soil organic matter, forming pyrolyzed compounds, and markedly reducing the diversity of microorganisms. Pyrophilous fungi, especially the species from Pezizales and Agaricales orders, are fire‐responsive fungal colonizers of post‐fire soil that have historically been found fruiting on...
Article
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The spatial structure of the environment is known to affect ecological processes. Unlike the spatial structure of negative interactions, such as competition and predation, the role of spatial structure in positive interaction has received less attention. We tested how the spatial structure of spores of ectomycorrhizal fungi (EMF) in the soil affect...
Article
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Fire effects on ecosystems range from destruction of aboveground vegetation to direct and indirect effects on belowground microorganisms. Although variation in such effects is expected to be related to fire severity, another potentially important and poorly understood factor is the effect of fire seasonality on soil microorganisms. We carried out a...
Article
Forest fires generate a large amount of carbon that remains resident on the site as dead and partially 'pyrolysed' (i.e. burnt) material that has long residency times and constitutes a significant pool in fire-prone ecosystems. In addition, fire-induced hydrophobic soil layers, caused by condensation of pyrolysed waxes and lipids, increase post-fir...
Preprint
Full-text available
Fire effects on ecosystems range from destruction of aboveground vegetation to direct and indirect effects on belowground microorganisms. Although variation in such effects is expected to be related to fire severity, another potentially important and poorly understood factor is the effects of fire seasonality on soil microorganisms. We carried out...
Article
Full-text available
Giant sequoia (Sequoiadendron giganteum ) is an iconic conifer that lives in relict populations on the western slopes of the California Sierra Nevada. In these settings, it is unusual among the dominant trees in that it associates with arbuscular mycorrhizal fungi rather than ectomycorrhizal fungi. However, it is unclear whether differences in micr...
Article
Following a late fall wildfire in 2016 in the Great Smoky Mountains National Park, pyrophilous fungi in burn zones were documented over a 2-y period with respect to burn severity and phenology. Nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) barcodes were obtained to confirm morphological evaluations. Forty-one taxa of Ascomycota and Ba...
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We have designed a pyrocosm to enable fine-scale dissection of post-fire soil microbial communities. Using it we show that the peak soil temperature achieved at a given depth occurs hours after the fire is out, lingers near this peak for a significant time, and is accurately predicted by soil depth and the mass of charcoal burned. Flash fuels that...
Article
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Ectomycorrhizal fungi (ECMF) are partners in a globally distributed tree symbiosis implicated in most major ecosystem functions. However, resilience of ECMF to future climates is uncertain. We forecast these changes over the extent of North American Pinaceae forests. About 68 sites from North American Pinaceae forests ranging from Florida to Ontari...
Article
In response to contemporary changes in climate, many tree species are shifting upslope to find favorable habitat. In the case of obligate ectomycorrhizal species, seedling growth above upper treeline depends on fungal spore availability. In the mountain ranges of the Great Basin, a recent shift in tree species stratification has been recorded, with...
Preprint
Full-text available
Giant sequoia (Sequoiadendron giganteum) is an iconic conifer that lives in relic populations on the western slopes of the California Sierra Nevada. In these settings it is unusual among the dominant trees in that it associates with arbuscular mycorrhizal fungi rather than ectomycorrhizal fungi. However, it is unclear whether differences in microbi...
Article
Full-text available
Rhizopogon olivaceotinctus is a rarely collected ectomycorrhizal fungus that has been found primarily in California and southern Oregon. Prior work has shown that it (i) is common in soil spore banks associated with pine forests from these areas; (ii) is rare or absent on trees in undisturbed forests in these same areas; (iii) exhibits an increased...
Preprint
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We have designed a simple, inexpensive system for the studying the response of soil microbes to fire. This system allows one to create post-fire environments in soil in reproducible and realistic ways. Using it we show that the peak soil temperature achieved at a given depth occurs hours after the fire is out, lingers near peak temperature for a si...
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Full-text available
Belowground biota can deeply influence plant invasion. The presence of proper soil mutualists can act as a driver that enable plants to colonize new ranges. We review the species of ectomycorrhizal fungi (EMF) that facilitate pine establishment in both native and non‐native ranges and that are associated with their invasion into nonforest settings....
Preprint
Ectomycorrhizal fungi (ECMF) are partners in a globally distributed tree symbiosis that enhanced ecosystem carbon (C)-sequestration and storage. However, resilience of ECMF to future climates is uncertain. We sampled ECMF across a broad climatic gradient in North America, modeled climatic drivers of diversity and community composition, and then for...
Article
Knowledge of the factors controlling the diverse chemical emissions of common environmental bacteria and fungi is crucial because they are important signal molecules for these microbes that also could influence humans. We show here not only a high diversity of mVOCs but that their abundance can differ greatly in different environmental contexts. Mi...
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Findings of immense microbial diversity are at odds with observed functional redundancy, as competitive exclusion should hinder coexistence. Tradeoffs between dispersal and competitive ability could resolve this contradiction, but the extent to which they influence microbial community assembly is unclear. Because fungi influence the biogeochemical...
Article
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A workshop at the recent International Conference on Mycorrhiza was focused on species recognition in Glomeromycotina and parts of their basic biology that define species. The workshop was motivated by the paradigm-shifting evidence derived from genomic data for sex and for the lack of heterokaryosis, and by published exchanges in Science that were...
Article
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Whether niche processes, like environmental filtering, or neutral processes, like dispersal limitation, are the primary forces driving community assembly is a central question in ecology. Here, we use a natural experimental system of isolated tree “islands” to test whether environment or geography primarily structures fungal community composition a...
Article
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Background Microorganisms influence the chemical milieu of their environment, and chemical metabolites can affect ecological processes. In built environments, where people spend the majority of their time, very little is known about how surface-borne microorganisms influence the chemistry of the indoor spaces. Here, we applied multidisciplinary app...
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The effects of spatial heterogeneity in negative biological interactions on individual performance and species diversity have been studied extensively. However, little is known about the respective effects involving positive biological interactions, including the symbiosis between plants and ectomycorrhizal (EM) fungi. Using a greenhouse bioassay,...
Article
Full-text available
The success of dispersal events depend on the organism's ability to reach and establish in a new habitat. In symbiotic organisms, establishment also depends on the presence of their symbiont partner in the new habitat. For instance, the establishment of obligate ectomycorrhizal (EM) trees outside the forest is largely limited by the presence of EM...
Article
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The theory of island biogeography, which predicts that species richness is a function of island size and distance from the mainland, is well tested with macro-fauna and flora. Yet, in many ways, microbes are more appropriate for testing this and other ecological theories due to their small size and short generation times that translate to an ease o...
Article
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The corticioid fungi are commonly encountered, highly diverse, ecologically important, and understudied. We collected specimens in 60 pine and spruce forests across North America to survey corticioid fungal frequency and distribution and to compile an internal transcribed spacer (ITS) database for the group. Sanger sequences from the ITS region of...
Article
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The genus Suillus represents one of the most recognizable groups of mushrooms in conifer forests throughout the Northern Hemisphere. Although for decades the genus has been relatively well defined morphologically, previous molecular phylogenetic assessments have provided important yet preliminary insights into its evolutionary history. Here we pres...
Article
Recent advancements in sequencing technology allowed researchers to better address the patterns and mechanisms involved in microbial environmental adaptation at large spatial scales. Here we investigated the genomic basis of adaptation to climate at the continental scale in Suillus brevipes, an ectomycorrhizal fungus symbiotically associated with t...
Data
Photograph of representative Pinus muricata seedlings from some of the heat and ectomycorrhizal (EM) treatments. No photograph of seedlings from the EM − / Heat + treatment was taken due to contamination (see text). Photo K.G. Peay
Article
In this study we analyzed the spatial structure of ectomycorrhizal fungi present in the soils as resistant propagules (e.g. spores or sclerotia) in a mixed-conifer forest in the Sierra Nevada, California. Soils were collected under old-growth Abies spp. stands across approximately 1 km and bioassayed with seedlings of hosts that establish best in s...
Article
Patterns of fungal spore dispersal affect gene flow, population structure and fungal community structure. Many Basidiomycota produce resupinate (crust-like) basidiocarps buried in the soil. Although spores are actively discharged, they often do not appear to be well positioned for aerial dispersal. We investigated the potential spore dispersal mech...
Article
In this study we examine the distribution of Rhizopogon species in spore banks from five California pine forests. Four of the forest sites were discontinuous populations of Pinus muricata and a fifth was a Pinus ponderosa stand in Sierra National Forest. Rhizopogon species were retrieved by bioassaying the soils with pine seedlings followed by isol...
Article
The position and composition of Macrolepiota within the Agaricaceae and its phylogenetic relationships with other members of the family were investigated, using both molecular (ITS and LSU rDNA sequences) and morphological characters. The molecular data separate the genus into two clades. The first clade comprises M. procera, M. mastoidea, M. clela...

Citations

... However, a prerequisite is that pyrophilous fungal mycelia and/or propagules must either be resistant to heat, have propagules in the "goldilocks zone," (Bruns et al. 2020), or rapidly invade burned soils from an external source (Kobziar et al. 2018 . 3), although some pyrophilous basidiomycetes exist (e.g., Pholiota carbonicola = Pholiota highlandensis, Lyophyllum atratatum; Matheny et al. 2018;Steindorff et al. 2021). In some cases, the fungal lifestyle may shift from mycorrhizal to saprotrophic following fire (Greene et al. 2010) and often from basidiomycete-to ascomycete-dominated communities (Cairney and Bastias 2007). ...
... Hygrocybe, frequently considered to be saprotrophic, can be found in a variety of habitats worldwide. While the exact trophic lifestyle of this genus remains unclear, it is possible that, considering the preponderance of Hygrocybe fungi in 1,073-m soils and their putative ability to act as root and systemic endophytes, these fungi may create ecologically essential symbiotic relationships with T. sutchuenensis, similar to an iconic conifer giant sequoia (Sequoiadendron giganteum) (54,55). The fungus Piloderma can grow on rock surfaces, accelerating rock decomposition and weathering, obtaining essential nutrients and releasing minerals (56,57). ...
... In Whitman et al., Mucoromycota increased at sites with higher burn severity [9]. Pezizales are known to have increased abundance of sporocarps after a burn [68,69], which would make them poised to colonize when the fire subsides. ...
... sPLS was sensitive to outliers; results focused on a cluster of Green Trail samples with high elevation and longitude, shown in the top cluster of Figure 4. Analysis revealed the cluster included the post-fire pioneer fungus Pyronema [6,39], Tremella, and Strobiloscypha, which produce strobiloscyphone antimicrobials [40]. Chlorellales algae, toxic Leptiota, and potentially pathogenic Fusarium sequences were elevated. ...
... Studying the effect of environmental changes on soil fungal community composition and diversity can enhance a comprehensive understanding of the entire ecosystem [3]. The α-diversity of soil fungi responds to climate change differently by trophic modes (i.e., symbiotroph, saprotroph, and pathotroph) [4,5], implying that the effect of different soil fungal trophic modes on ecosystem functioning needs to be explored in the future. Mountains provide an open, natural platform for studying how soil microbes respond to environmental change, especially climate change, at short altitude distances [6]. ...
... Moreover, the distribution of Endoradiciella is apparently not limited to Europe but also includes western North America and China. Available ITS sequences also suggest several conspecific isolates recovered from roots of Pinus flexilis (Pinaceae) seedlings in the US state of California (Shemesh et al. 2020) and Populus spp. (Salicaceae) in Oregon, Washington, and the Canadian province of British Columbia (Bonito et al. 2016). ...
... 3B) can survive wildfires (Baynes et al. 2011;Greene et al. 2010), and some fungi likely have persistent, heat-resistant spores, for example, Rhizopogon olivaceotinctus (FIG. 3K;Baar et al. 1999;Glassman et al. 2016;Bruns et al. 2019), Ascobolus carbonarius, and Trichophaea abundans (conidia and ascospores; Msh and Webster 1968b). Others may survive as mycelia in mycorrhizae or soil, as exemplified by ...
... Similar to previous studies (Bruns et al., 2019;Cairney and Bastias, 2007;Fujimura et al., 2005;Reazin et al., 2016;Smith et al., 2004;Visser, 1995;Yang et al., 2020), we observed a shift in dominance in the burned sites, from Basidiomycete-to Ascomycete-dominated. The emergence and dominance of Chromelosporium and Pustularia, both rare in the unburned sites, supports previous findings that cryptic and rare taxa tend to dominate the burned environment (Bruns et al., 2019;Fujimura et al., 2005;Horton and Bruns, 1998;Hughes et al., 2020;Smith et al., 2004;Visser, 1995). ...
... This last trait is essential during the colonization of novel sites, since some EM fungal spores, unlike extraradical hyphae, can survive unfavorable soil conditions until seedlings establish (Horton, 2017). Hence, the ability to form a resistant spore bank, high production of spores and multiple abiotic and biotic dispersal vectors have allowed good dispersers such as Suilloid fungi (Suillus and Rhizopogon EM fungal species) to dominate pine invasion fronts worldwide, especially far from the original inoculum source Policelli et al., 2019). ...
... As fungal cells usually contain several up to several hundred copies of rRNA coding genes [57], an assay based on one of those units, i.e. the IGS sequence, is supposed to provide a higher number of primer binding sites per DNA molecule and should thus have a higher sensitivity for the detection of its target organism. Our results fully confirmed this expectation because the IGS-based assay was about 100-fold more sensitive compared to the single-copy gene acl1 assay. ...