Frequent fire reorganizes fungal communities and slows decomposition across a heterogeneous pine savanna landscape

© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust Pyrogenic savannas with a tree–grassland ‘matrix’ experience frequent fires (i.e. every 1–3 yr). Aboveground responses to frequent fires have been well studied, but responses of fungal litter decomposers, which directly affect fuels, remain poorly known. We hypothesized that each fire reorganizes belowground communities and slows litter decomposition, thereby influencing savanna fuel dynamics. In a pine savanna, we established patches near and away from pines that were either burned or unburned in that year. Within patches, we assessed fungal communities and microbial decomposition of newly deposited litter. Soil variables and plant communities were also assessed as proximate drivers of fungal communities. Fungal communities, but not soil variables or vegetation, differed substantially between burned and unburned patches. Saprotrophic fungi dominated in unburned patches but decreased in richness and relative abundance after fire. Differences in fungal communities with fire were greater in litter than in soils, but unaffected by pine proximity. Litter decomposed more slowly in burned than in unburned patches. Fires drive shifts between fire-adapted and sensitive fungal taxa in pine savannas. Slower fuel decomposition in accordance with saprotroph declines should enhance fuel accumulation and could impact future fire characteristics. Thus, fire reorganization of fungal communities may enhance persistence of these fire-adapted ecosystems

Abrupt changes in the composition and function of fungal communities along an environmental gradient in the High Arctic

Fungi play a key role in soil-plant interactions, nutrient cycling and carbon flow and are essential for the functioning of arctic terrestrial ecosystems. Some studies have shown that the composition of fungal communities is highly sensitive to variations in environmental conditions, but little is known about how the conditions control the role of fungal communities (i.e., their ecosystem function). We used DNA metabarcoding to compare taxonomic and functional composition of fungal communities along a gradient of environmental severity in Northeast Greenland. We analysed soil samples from fell fields, heaths and snowbeds, three habitats with very contrasting abiotic conditions. We also assessed within-habitat differences by comparing three widespread microhabitats (patches with high cover of Dryas, Salix, or bare soil). The data suggest that, along the sampled mesotopographic gradient, the greatest differences in both fungal richness and community composition are observed amongst habitats, while the effect of microhabitat is weaker, although still significant. Furthermore, we found that richness and community composition of fungi are shaped primarily by abiotic factors and to a lesser, though still significant extent, by floristic composition. Along this mesotopographic gradient, environmental severity is strongly correlated with richness in all fungal functional groups: positively in saprotrophic, pathogenic and lichenised fungi, and negatively in ectomycorrhizal and root endophytic fungi. Our results suggest complex interactions amongst functional groups, possibly due to nutrient limitation or competitive exclusion, with potential implications on soil carbon stocks. These findings are important in the light of the environmental changes predicted for the Arctic

Tundra Type Drives Distinct Trajectories of Functional and Taxonomic Composition of Arctic Fungal Communities in Response to Climate Change – Results From Long-Term Experimental Summer Warming and Increased Snow Depth

The arctic tundra is undergoing climate-driven changes and there are serious concerns related to the future of arctic biodiversity and altered ecological processes under possible climate change scenarios. Arctic land surface temperatures and precipitation are predicted to increase further, likely causing major transformation in terrestrial ecosystems. As a response to increasing temperatures, shifts in vegetation and soil fungal communities have already been observed. Little is known, however, how long-term experimental warming coupled with increased snow depth influence the trajectories of soil fungal communities in different tundra types. We compared edaphic variables and fungal community composition in experimental plots simulating the expected increase in summer warming and winter snow depth, based on DNA metabarcoding data. Fungal communities in the sampled dry and moist acidic tundra communities differed greatly, with tundra type explaining ca. one-third of compositional variation. Furthermore, dry and moist tundra appear to have different trajectories in response to climate change. Specifically, while both warming and increased snow depth had significant effects on fungal community composition and edaphic variables in dry tundra, the effect of increased snow was greater. However, in moist tundra, fungal communities mainly were affected by summer warming, while increased snow depth had a smaller effect and only on some functional groups. In dry tundra, microorganisms generally are limited by moisture in the summer and extremely low temperatures in winter, which is in agreement with the stronger effect of increased snow depth relative to warming. On the contrary, moist tundra soils generally are saturated with water, remain cold year-round and show relatively small seasonal fluctuations in temperature. The greater observed effect of warming on fungi in moist tundra may be explained by the narrower temperature optimum compared to those in dry tundra

Fungal community structure and seasonal trajectories respond similarly to fire across pyrophilic ecosystems

This is a pre-copyedited, author-produced version of an article accepted for publication in FEMS Microbiology Ecology following peer review. The version of record Jacob R Hopkins, Tatiana Semenova-Nelsen, Benjamin A Sikes, Fungal community structure and seasonal trajectories respond similarly to fire across pyrophilic ecosystems, FEMS Microbiology Ecology, Volume 97, Issue 1, January 2021, fiaa219, https://doi.org/10.1093/femsec/fiaa219 is available online at: https://doi.org/10.1093/femsec/fiaa219 and https://academic.oup.com/femsec/article/97/1/fiaa219/5956485?login=trueFire alters microbial community composition, and is expected to increase in frequency due to climate change. Testing whether microbes in different ecosystems will respond similarly to increased fire disturbance is difficult though, because fires are often unpredictable and hard to manage. Fire recurrent or pyrophilic ecosystems, however, may be useful models for testing the effects of frequent disturbance on microbes. We hypothesized that across pyrophilic ecosystems, fire would drive similar alterations to fungal communities, including altering seasonal community dynamics. We tested fire's effects on fungal communities in two pyrophilic ecosystems, a longleaf pine savanna and tallgrass prairie. Fire caused similar fungal community shifts, including (i) driving immediate changes that favored taxa able to survive fire and take advantage of post-fire environments and (ii) altering seasonal trajectories due to fire-associated changes to soil nutrient availability. This suggests that fire has predictable effects on fungal community structure and intra-annual community dynamics in pyrophilic ecosystems, and that these changes could significantly alter fungal function. Parallel fire responses in these key microbes may also suggest that recurrent fires drive convergent changes across ecosystems, including less fire-frequented systems that may start burning more often due to climate change

Recurrent fires do not affect the abundance of soil fungi in a frequently burned pine savanna

© 2019 Elsevier Ltd and British Mycological Society While the negative effects of infrequent, high-intensity fire on soil fungal abundance are well-understood, it remains unclear how the short-term history of frequent, low-intensity fire in fire-dependent ecosystems impacts abundance, and whether this history governs any abundance declines. We used prescribed fire to experimentally alter the short-term fire history of patches within a fire-frequented old-growth pine savanna over a 3 y period. We then quantified fungal abundance before and after the final fire using phospholipid fatty acid (PLFA) assays and Droplet Digital™ PCR (ddPCR). Short-term fire history largely did not affect total fungal abundance nor pre-to post-fire abundance shifts. While producing similar conclusions, PLFA and ddPCR data were not correlated. In addition to piloting a new method to quantify soil fungal abundance, our findings indicate that, within fire-frequented pine savannas, recurrent fires do not consistently decrease total fungal abundance, and abundance changes are not contingent upon short-term fire history. This suggests that many fungi in fire-dependent ecosystems are fire-tolerant

Abrupt changes in the composition and function of fungal communities along an environmental gradient in the high Arctic

Fungi play a key role in soil–plant interactions, nutrient cycling and carbon flow and are essential for the functioning of arctic terrestrial ecosystems. Some studies have shown that the composition of fungal communities is highly sensitive to variations in environmental conditions, but little is known about how the conditions control the role of fungal communities (i.e., their ecosystem function). We used DNA metabarcoding to compare taxonomic and functional composition of fungal communities along a gradient of environmental severity in Northeast Greenland. We analysed soil samples from fell fields, heaths and snowbeds, three habitats with very contrasting abiotic conditions. We also assessed within-habitat differences by comparing three widespread microhabitats (patches with high cover of Dryas, Salix, or bare soil). The data suggest that, along the sampled mesotopographic gradient, the greatest differences in both fungal richness and community composition are observed amongst habitats, while the effect of microhabitat is weaker, although still significant. Furthermore, we found that richness and community composition of fungi are shaped primarily by abiotic factors and to a lesser, though still significant extent, by floristic composition. Along this mesotopographic gradient, environmental severity is strongly correlated with richness in all fungal functional groups: positively in saprotrophic, pathogenic and lichenised fungi, and negatively in ectomycorrhizal and root endophytic fungi. Our results suggest complex interactions amongst functional groups, possibly due to nutrient limitation or competitive exclusion, with potential implications on soil carbon stocks. These findings are important in the light of the environmental changes predicted for the Arctic.This research was supported by the Synergy grant ERC-SyG-610028IMBALANCE-P and by INTERACT (grant agreement num. 262693)under the European Community’s Seventh Framework Program. Themolecular work was sponsored by a Naturalis Research Initiativegrant awarded to J. Geml. The authors thank Marina Perez (University of Barcelona) for helping in the laboratory and MarcelEurlings and Elza Duijm (Naturalis) for conducting the Ion Torrentsequencing. We are grateful to the staff at the Zackenberg ResearchStation for logistical support.Peer reviewe

Abrupt changes in the composition and function of fungal communities along an environmental gradient in the High Arctic

Fungi play a key role in soil-plant interactions, nutrient cycling and carbon flow and are essential for the functioning of arctic terrestrial ecosystems. Some studies have shown that the composition of fungal communities is highly sensitive to variations in environmental conditions, but little is known about how the conditions control the role of fungal communities (i.e., their ecosystem function). We used DNA metabarcoding to compare taxonomic and functional composition of fungal communities along a gradient of environmental severity in Northeast Greenland. We analysed soil samples from fell fields, heaths and snowbeds, three habitats with very contrasting abiotic conditions. We also assessed within-habitat differences by comparing three widespread microhabitats (patches with high cover of Dryas, Salix, or bare soil). The data suggest that, along the sampled mesotopographic gradient, the greatest differences in both fungal richness and community composition are observed amongst habitats, while the effect of microhabitat is weaker, although still significant. Furthermore, we found that richness and community composition of fungi are shaped primarily by abiotic factors and to a lesser, though still significant extent, by floristic composition. Along this mesotopographic gradient, environmental severity is strongly correlated with richness in all fungal functional groups: positively in saprotrophic, pathogenic and lichenised fungi, and negatively in ectomycorrhizal and root endophytic fungi. Our results suggest complex interactions amongst functional groups, possibly due to nutrient limitation or competitive exclusion, with potential implications on soil carbon stocks. These findings are important in the light of the environmental changes predicted for the Arctic

Data from: Abrupt changes in the composition and function of fungal communities along an environmental gradient in the High Arctic

Fungi play a key role in soil-plant interactions, nutrient cycling, and carbon flow and are essential for the functioning of arctic terrestrial ecosystems. Some studies have shown that the composition of fungal communities is highly sensitive to variations in environmental conditions, but little is known about how the conditions control the role of fungal communities (i.e. their ecosystem function). We used DNA metabarcoding to compare taxonomic and functional composition of fungal communities along a gradient of environmental severity in Northeast Greenland. We analysed soil samples from fell fields, heaths, and snowbeds, three habitats with very contrasting abiotic conditions. We also assessed within-habitat differences by comparing three widespread microhabitats (patches with high cover of Dryas, Salix, or bare soil). The data suggest that, along the sampled mesotopographic gradient, the greatest differences in both fungal richness and community composition are observed among habitats, while the effect of microhabitat is weaker, although still significant. Furthermore, we found that richness and community composition of fungi are shaped primarily by abiotic factors and to a lesser, though still significant extent, by floristic composition. Along this mesotopographic gradient, environmental severity is strongly correlated with richness in all fungal functional groups: positively in saprotrophic, pathogenic, and lichenised fungi, and negatively in ectomycorrhizal and root-endophytic fungi. Our results suggest complex interactions amongst functional groups, possibly due to nutrient limitation or competitive exclusion, with potential implications on soil carbon stocks. These findings are important in light of the environmental changes predicted for the Arctic

Fire as a driver of fungal diversity - A synthesis of current knowledge

Fires occur in most terrestrial ecosystems where they drive changes in the traits, composition, and diversity of fungal communities. Fires range from rare, stand-replacing wildfires to frequent, prescribed fires used to mimic natural fire regimes. Fire regime factors, including burn severity, fire intensity, and timing, vary widely and likely determine how fungi respond to fires. Despite the importance of fungi to post-fire plant communities and ecosystem functioning, attempts to identify common fungal responses and their major drivers are lacking. This synthesis addresses this knowledge gap and ranges from fire adaptations of specific fungi to succession and assembly fungal communities as they respond to spatially heterogenous burning within the landscape. Fires impact fungi directly and indirectly through their effects on fungal survival, substrate and habitat modifications, changes in environmental conditions, and/or physiological responses of the hosts with which fungi interact. Some specific pyrophilous, or fire-loving, fungi often appear after fire. Our synthesis explores whether such taxa can be considered cosmopolitan, and whether they are truly fire-adapted or simply opportunists adapted to rapidly occupy substrates and habitats made available by fires. We also discuss the possible inoculum sources of post-fire fungi and explore existing conceptual models and ecological frameworks that may be useful in generalizing fungal fire responses. We conclude with identifying research gaps and areas that may best transform the current knowledge and understanding of fungal responses to fire

Community dynamics of soil-borne fungal communities along elevation gradients in neotropical and palaeotropical forests

Because of their steep gradients in abiotic and biotic factors, mountains offer an ideal setting to illuminate the mechanisms that underlie patterns of species distributions and community assembly. We compared the composition of taxonomically and functionally diverse fungal communities in soils along five elevational gradients in mountains of the Neo- and Palaeotropics (northern Argentina, southern Brazil, Panama, Malaysian Borneo and Papua New Guinea). Both the richness and composition of soil fungal communities reflect environmental factors, particularly temperature and soil pH, with some shared patterns among neotropical and palaeotropical regions. Community dynamics are characterized by replacement of species along elevation gradients, implying a relatively narrow elevation range for most fungi, which appears to be driven by contrasting environmental preferences among both functional and taxonomic groups. For functional groups dependent on symbioses with plants (especially ectomycorrhizal fungi), the distribution of host plants drives richness and community composition, resulting in important differences in elevational patterns between neotropical and palaeotropical montane communities. The pronounced compositional and functional turnover along elevation gradients implies that tropical montane forest fungi will be sensitive to climate change, resulting in shifts in composition and functionality over time.Fil: Geml, József. Naturalis Biodiversity Center; Países Bajos. Eszterházy Károly Catholic University; HungríaFil: Arnold, Anne Elizabeth. University of Arizona; Estados UnidosFil: Semenova Nelsen, Tatiana A.. Naturalis Biodiversity Center; Países BajosFil: Nouhra, Eduardo Ramon. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Drechsler Santos, Elisandro R.. Universidade Federal de Santa Catarina; BrasilFil: Góes Neto, Aristóteles. Universidade Federal de Minas Gerais; BrasilFil: Morgado, Luis N.. Naturalis Biodiversity Center; Países Bajos. University of Oslo; NoruegaFil: Ódor, Péter. Institute Of Ecology And Botany; HungríaFil: Hegyi, Balázs. Debreceni Egyetem; Hungría. Eszterházy Károly Catholic University; HungríaFil: Oriol, Grau. Univeristé Antilles; Guayana Francesa. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; EspañaFil: Ibáñez, Alicia. University of Arizona; Estados UnidosFil: Tedersoo, Leho. Tartu Ülikool; EstoniaFil: Lutzoni, François. University of Duke; Estados Unido