Functional Guilds Research Articles

Climate‐mediated shifts toward bunchgrass dominance 40 years after grazing cessation in Saguaro National Park, Arizona, USA

AbstractQuestionsVegetation transects were surveyed in Saguaro National Park, Arizona, in 1976 and 2007 as part of a grazing study. We resurveyed the same transects in 2018 and accessed fire and climate data in order to examine trends in plant community structure. We asked the question: has the plant community shifted in species’ density, canopy cover and diversity in the past 40 years since grazing cessation? And if so, do these shifts favor a specific species, or plant functional guild? We also asked if climate and time since fire influenced plant community structure?LocationSaguaro National Park East is located in the Sonoran Desert and Madrean Sky Island ecoregion interface in Tucson, Arizona, United States.MethodsPlots (10) were 20 m × 50 m, with 21 20‐m transects within each plot used to gather plant canopy cover and density of perennial species with the line‐intercept method. Data were aggregated by plot and analyzed using generalized linear mixed‐effects modeling and non‐metric multi‐dimensional scaling.ResultsOverall canopy cover, density, and Shannon diversity increased significantly between 1976 and 2018. Ferns, forbs, graminoids, subshrubs and vines increased significantly in cover and density between 1976 and 2018. Wildfire recency was significantly negatively correlated with forb density, and density or cover of five dominant species (mostly woody). Shifts in plant community structure between survey years was correlated with increased temperature, precipitation, and vapor pressure differential.ConclusionAfter 40 years of grazing cessation, significant increases in herbaceous cover, and a lack of significant increase in woody encroachment are signs of recovery. Increases in temperature may be responsible for accelerating shifts to warm‐season species‐dominant communities. Fire was unexpectedly not a significant factor in plant community structure; however, park management will likely need to address increased wildfire risk given the increase in herbaceous cover and density.

Soil Fungal Communities and Enzyme Activities along Local Tree Species Diversity Gradient in Subtropical Evergreen Forest

The majority of studies have found that an increase in tree species diversity can increase the productivity of forest stands thanks to complimentary effects with enhanced resource use efficiency or selection effects; however, it is unclear how tree species diversity affects the soil fungal community and enzyme activities in subtropical evergreen forests. In this study, we used soil high-throughput sequencing to investigate the soil fungal community structure and diversity in the central area of tree clusters in the gradient of tree species richness formed by four possible dominant tree species (Pinus massoniana Lamb., Choerospondias axillaris Roxb., Cyclobalanopsis glauca Thunb. and Lithocarpus glaber Thunb.) in subtropical evergreen broad-leaved forest. The results showed that soil organic carbon content and total nitrogen content were significantly higher in mixed tree clusters, and that soil fungal richness and diversity increased with the increase in tree species diversity (1–3 species). Soil acid phosphatase and urease activity were also enhanced with tree species diversity (p < 0.05). The relative abundance of soil symbiotic fungi (ectomycorrhizal fungi) decreased, while the relative abundance of saprotrophic fungi increased. Redundancy analysis (RDA) revealed that soil acid phosphatase activity was the main factor affecting soil fungal communities and functional guilds, and that soil water content was the main driving force behind fungal trophic modes. In subtropical forests, changes in tree species diversity have altered the soil fungal community structure and trophic modes and functions, accelerating the decomposition of organic matter, increasing nutrient cycling, and perhaps also changing the nutrient absorption of trees.

Tree species composition and soil properties in pure and mixed beech-conifer stands drive soil fungal communities

Soil fungi, especially the functional guilds of saprotrophs and symbiotrophs, play a central role in ecosystem processes such as decomposition and plant nutrient acquisition. Fungal communities are influenced by soil properties and management strategies such as tree species selection. Yet, the implications of the enrichment of temperate forests consisting of tree species in their native range with non-native tree species on soil fungal diversity and their functional groups are unknown. Here, we studied fungal communities in 40 plots (2500 m2 size per plot) located in two regions differing in site conditions (nutrient content, soil moisture and climate) in forests composed of European beech, spruce and Douglas-fir (non-native) and mixtures of beech with either spruce or Douglas-fir. We hypothesized that fungal community structures are driven by soil properties and tree species composition, generally resulting in higher fungal diversity in mixed than in mono-specific forests. We further hypothesized that Douglas-fir has a negative effect on ectomycorrhizal fungal species richness compared to native species, whereas saprotrophic fungal richness is unaffected. Fungal DNA barcoding and dissimilarity analyses showed significant separation of fungal communities between nutrient-rich and nutrient-poor regions and among forest types. Mycorrhizal species richness did not vary with forest type, but the relative abundance of mycorrhizal species was lower in Douglas-fir and mixed beech-Douglas-fir forests than in spruce or beech-spruce mixture forests. Conifer forests contained higher relative abundances of saprotrophic fungi than mono-specific beech forests. Among 16 abundant fungal orders in the soil, two containing saprotrophic fungi (Tremellales and Hymenochaetales) were enriched in conifer forests, regardless of site conditions and tree species mixture. The other fungal orders, including those dominated by mycorrhizal fungi (Russulales, Boletales, Atheliales and Cantharellales) showed variable patterns depending on site conditions and tree species. Our results show the impact of tree species composition and soil properties on soil fungi. The response of fungal guilds and taxa to forest types and soil properties can potentially influence nutrient fluxes.

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.

Microplastics accumulation in functional feeding guilds and functional habit groups of freshwater macrobenthic invertebrates: Novel insights in a riverine ecosystem

Microplastics pose a major threat for aquatic ecosystems, but the contamination dynamics in organisms inhabiting freshwater ecosystems is still little studied. Largely used for biomonitoring, macrobenthic invertebrates provide a pivotal trophic resource for many fish and bird species. In this study, we investigated the microplastics contamination in a macrobenthic invertebrate community (2772 individuals belonging to 33 taxa identified) in a high-plain riverine ecosystem (Vipacco River, northeast Italy) and compared the amount of microplastics accumulated in functional feeding guilds/functional habit groups. Microplastics (cellulosic fibers associated with polyester) were found in 48.5% of the taxa, with the highest amount detected in the collector-gatherers, followed by predators. The collector-gatherers showed a significantly higher microplastic accumulation than the other functional feeding guilds, whereas there was no difference among the functional habit groups. The main source of microplastics pollution was most likely urban wastewater discharge points located along the river. Our study reports a novel approach about microplastic pollution assessment in lotic environments, as it focuses into the microplastic contamination dynamics in an entire macrobenthic invertebrate community perspective and underlines the need for further study.

Facilitation by isolated trees triggers woody encroachment and a biome shift at the savanna–forest transition

Abstract Woody encroachment into grassy biomes is a global phenomenon, often resulting in a nearly complete turnover of species, with savanna specialists being replaced by forest‐adapted species. Understanding the mechanisms involved in this change is important for devising strategies for managing savannas. We examined how isolated trees favour woody encroachment and species turnover by overcoming dispersal limitation and environmental filtering. In a savanna released from fire in south‐eastern Brazil (Cerrado), we sampled woody plants establishing under 40 tree canopies and in paired treeless plots. These trees comprised eight species selected for habitat preference (savanna or forest) and dispersal syndrome (bird dispersed or not). We recorded dimensions of each tree, dispersal syndrome and habitat preference of recruits, and quantified the physical environment within each plot, aiming at a mechanistic understanding of woody encroachment. We found clear evidence that isolated trees cause nucleation and drive changes in functional composition of savanna. Effectiveness as nucleator differed among species, but was unrelated to their functional guilds (habitat preference or dispersal syndrome). The density of saplings in nuclei was partially explained by soil moisture (+), daily temperature amplitude (−) and sum of bases (−). Our results indicate that isolated trees act first as perches, strongly favouring bird‐dispersed species. They then act as nurse trees, considerably changing the environment in favour of forest‐adapted recruits. In the long term, as the nuclei expand and merge, savanna specialists tend to disappear and the savanna turns into a low‐diversity forest. Synthesis and applications. Fire suppression has allowed the nucleation process and consequently the woody encroachment and fast replacement of savanna specialists by forest species in the Cerrado. By elucidating the mechanisms behind woody encroachment, we recommend using prescribed fires to burn forest seedlings and to reduce tree canopy size wherever the management goal is to maintain the typical savanna structure and composition.

Adaptation of Soil Fungal Community Structure and Assembly to Long- Versus Short-Term Nitrogen Addition in a Tropical Forest.

Soil fungi play critical roles in ecosystem processes and are sensitive to global changes. Elevated atmospheric nitrogen (N) deposition has been well documented to impact on fungal diversity and community composition, but how the fungal community assembly responds to the duration effects of experimental N addition remains poorly understood. Here, we aimed to investigate the soil fungal community variations and assembly processes under short- (2 years) versus long-term (13 years) exogenous N addition (∼100 kg N ha–1 yr–1) in a N-rich tropical forest of China. We observed that short-term N addition significantly increased fungal taxonomic and phylogenetic α-diversity and shifted fungal community composition with significant increases in the relative abundance of Ascomycota and decreases in that of Basidiomycota. Short-term N addition also significantly increased the relative abundance of saprotrophic fungi and decreased that of ectomycorrhizal fungi. However, unremarkable effects on these indices were found under long-term N addition. The variations of fungal α-diversity, community composition, and the relative abundance of major phyla, genera, and functional guilds were mainly correlated with soil pH and NO3––N concentration, and these correlations were much stronger under short-term than long-term N addition. The results of null, neutral community models and the normalized stochasticity ratio (NST) index consistently revealed that stochastic processes played predominant roles in the assembly of soil fungal community in the tropical forest, and the relative contribution of stochastic processes was significantly increased by short-term N addition. These findings highlighted that the responses of fungal community to N addition were duration-dependent, i.e., fungal community structure and assembly would be sensitive to short-term N addition but become adaptive to long-term N enrichment.

Quantification of the global impact of agricultural practices on soil nematodes: A meta-analysis

Agricultural practices significantly affect soil biodiversity and functions, altering biogeochemical cycles and potentially compromising food production. Increased employment of sustainable agricultural practices is of growing policy concern and requires a better understanding and quantification of how agriculture affects soil functioning. We conducted a worldwide meta-analysis by computing 4855 effect sizes from 103 publications to quantify the effect of agricultural practices on soil nematodes, known to be key biological indicators of soil health. Our meta-analysis summarized the effects of tillage, pesticides use, fertilization, manipulation of above-ground plant including cover crop, rotation and agricultural system shift (the conversion from the conventional to conservation or organic agriculture systems). We quantified how each agricultural practice alters nematode indices of ecological relevance including the absolute abundance of trophic groups, the taxonomic richness and diversity and the food web structure based on functional guilds. At the global level, organo-mineral fertilization, conservation system, cover crop and nematicides exhibited the greatest effect sizes (averaged all nematode indices) while herbicides, plant association, mineral fertilization and tillage had the lowest ones. At the level of trophic groups, the agricultural practices had varying impacts, e.g. crop rotation mainly reduced the abundance of the plant-feeding nematodes (−47%), cover crop mainly increased the abundance of omnivore-predators (+80%) while organic fertilization predominately promoted bacterial (+113%) and fungal feeders (+141%). Crop rotation reduced the absolute abundance of plant feeders by 47% when the rotation is longer than 2 years. At the community level, chemical inputs, monoculture and pesticide application reduced nematode abundance, the food web structure and favoured copiotrophic nematode communities. Biocides and nematicides reduced total abundance, Shannon diversity and the food web complexity of soil nematode (structure index). Using meta-regressions, our meta-analysis revealed that the effect of agricultural practices depends on the time since the last agricultural intervention (e.g. input of fertilizers, pesticide application) and on how long a practice has been adopted. This study will be a useful aid for decision maker to better manage soil nematode community and to identify gaps in current available literature. In providing the direction and magnitude of soil nematode responses to agricultural practices, the effect size produced by this study are critical in facilitating worldwide modelling of soil biodiversity under global change scenarios.

Predicting Macroinvertebrate Responses to Water Abstraction in Alpine Streams

Exploitation of hydropower potential in alpine areas undermines the ecological integrity of rivers. Damming and water abstraction substantially alter the physical habitat template of rivers, with strong repercussions on aquatic communities and their resources. Tools are needed to predict and manage the consequences of these alterations on the structure and functioning of macroinvertebrate communities and resource availability in alpine streams. We developed habitat preference models for taxa, functional feeding guilds, and organic resources to quantify the effects of discharge alteration on macroinvertebrate communities in two alpine streams. Our physical habitat model related an indirect measure of bottom hydraulic forces (FST hemispheres) to the distribution of macroinvertebrate taxa and their resources. We observed that flow-dependent habitat availability for macroinvertebrate communities generally decreased with increasing water abstraction. We were able to relate these changes to near-bed hydraulic conditions. Our results suggest, however, the existence of upper discharge thresholds delimiting optimal habitat conditions for taxa. In contrast, we found weak effects of near-bed hydraulic conditions on resource distribution. Overall, our findings contribute towards predicting the impacts of water abstraction on macroinvertebrate communities in small alpine streams and the benefits of baseflow restoration.

Moso bamboo invasion has contrasting effects on soil bacterial and fungal abundances, co-occurrence networks and their associations with enzyme activities in three broadleaved forests across subtropical China

Moso bamboo (Phyllostachys edulis) invasions into adjacent forests have been reported to threaten aboveground biodiversity and alter belowground soil processes. However, the impacts of bamboo invasion on soil microbial community composition, co-occurrence network and enzyme activity remain largely unknown. We presented a cross site field investigation on soil bacterial and fungal communities and enzyme activities in three forests (an original broadleaf forest, a mixed bamboo-broadleaf forest and a pure bamboo forest) at three sites in South China. Our results showed that bamboo invasion consistently increased soil pH (by 6.72% − 17.56%) and soil organic carbon concentrations (by 11.75% − 40.63%) across the three sites. Bamboo invasion consistently decreased fungal ITS gene abundances across the sites, but had little effect on bacterial 16S rRNA gene abundances and diversity indices. The community composition of both bacteria and fungi and their functional guilds differed among the three sites and were significantly (P < 0.05) affected by bamboo invasion. Bamboo invasion significantly decreased the relative abundances of ectomycorrhizal but increased those of soil saprotrophs. The complexity of co-occurrence network of bacterial communities was increased whereas that of fungal communities was decreased due to bamboo invasion. The activities of soil enzymes involved in C, N and P cycling were also altered by bamboo invasion, and they were significantly positively correlated with the abundances of fungal ITS gene and ectomycorrhizal rather than those of bacteria and predicted metabolic function. This study suggested that bamboo invasions into adjacent broadleaf forests had contrasting effects on soil bacterial and fungal communities by shifting microhabitats towards a condition that is unfavorable for some fungal functional guilds, which were tightly associated with soil functioning. These results highlight the need for sustainable forestry management against bamboo invasion to maintain fungal diversity and network complexity.

An inventory of the foliar, soil, and dung arthropod communities in pastures of the southeastern United States.

Grassland systems constitute a significant portion of the land area in the United States and as a result harbors significant arthropod biodiversity. During this time of biodiversity loss around the world, bioinventories of ecologically important habitats serve as important indicators for the effectiveness of conservation efforts. We conducted a bioinventory of the foliar, soil, and dung arthropod communities in 10 cattle pastures located in the southeastern United States during the 2018 grazing season. In sum, 126,251 arthropod specimens were collected. From the foliar community, 13 arthropod orders were observed, with the greatest species richness found in Hymenoptera, Diptera, and Hemiptera. The soil‐dwelling arthropod community contained 18 orders. The three orders comprising the highest species richness were Coleoptera, Diptera, and Hymenoptera. Lastly, 12 arthropod orders were collected from cattle dung, with the greatest species richness found in Coleoptera, Diptera, and Hymenoptera. Herbivores were the most abundant functional guild found in the foliar community, and predators were most abundant in the soil and dung communities. Arthropod pests constituted a small portion of the pasture arthropod communities, with 1.01%, 0.34%, and 0.46% pests found in the foliar, soil, and dung communities, respectively. While bioinventories demand considerable time, energy, and resources to accomplish, the information from these inventories has many uses for conservation efforts, land management recommendations, and the direction of climate change science.

Friend and foe? The effects of grassland management on global patterns of spider diversity

1. Grassland ecosystems have been used worldwide for food production through pastoral and cropping activities. In these ecosystems, spiders constitute important mesopredators, which are affected by grassland management in opposite ways. Historically, the spider taxonomic diversity has been the main focus in studies of grazing impacts in grassland ecosystems, while the intrinsic variability of traits within spiders have been neglected, which may have led to mistaken conclusions. Our objective is to reanalyse the effects of grazing on spider taxonomic and functional guilds on worldwide grasslands.2. We conducted a systematic review of the literature from the last 10 years, to assess the influence of grazing on the taxonomic and functional guild diversity of spiders worldwide. Using Generalised Linear Mixed Models, we assessed the effects of grazing pressure and type of herd on abundance, richness of spider species, and guilds.3. In the taxonomic perspective, we found no evidence of grazing impact on the abundance and richness of spiders. However, in the functional guild perspective, high grazing pressure reduced the diversity of web building spiders and enhanced diversity of ground dwelling spiders. Moreover, pastures containing more than one grazing species enhanced the diversity of ambush spiders.4. Overall, the functional guild diversity of spiders in grassland ecosystems seems to be more influenced by grazing intensity. Our results suggest that grazing intensity can change the guild composition of the araneofauna in grasslands, with guilds responding differently to grazing.

Mass-immigration determines the assembly of activated sludge microbial communities

The assembly of bacterial communities in wastewater treatment plants (WWTPs) is affected by immigration via wastewater streams, but the impact and extent of bacterial immigrants are still unknown. Here, we quantify the effect of immigration at the species level in 11 Danish full-scale activated sludge (AS) plants. All plants have different source communities but have very similar process design, defining the same overall environmental growth conditions. The AS community composition in each plant was strongly reflected by the corresponding influent wastewater (IWW) microbial composition. Most species in AS across the plants were detected and quantified in the corresponding IWW, allowing us to identify their fate in the AS: growing, disappearing, or surviving. Most of the abundant species in IWW disappeared in AS, so their presence in the AS biomass was only due to continuous mass-immigration. In AS, most of the abundant growing species were present in the IWW at very low abundances. We predicted the AS species abundances from their abundance in IWW by using a partial least square regression model. Some species in AS were predicted by their own abundance in IWW, while others by multiple species abundances. Detailed analyses of functional guilds revealed different prediction patterns for different species. We show, in contrast to the present understanding, that the AS microbial communities were strongly controlled by the IWW source community and could be quantitatively predicted by taking into account immigration. This highlights a need to revise the way we understand, design, and manage the microbial communities in WWTPs.

Changes in the root fungal microbiome of strawberry following application of residues of the biofumigant oilseed radish

Biofumigation has been proposed as an environmentally friendly method of plant protection against soil-borne pathogens, but its effects on microbial communities are still incompletely understood. Using high throughput DNA sequencing, we investigated the effects of oilseed radish residues on the root fungal microbiome of strawberry in the presence of a soil-borne fungal pathogen, Verticillium dahliae. Results of our greenhouse study show that early flowering occurred in response to residue addition, suggesting a plant stress-response and there was a significant decrease in berry yield. The fungal microbiome of roots was significantly restructured by both biofumigation and inoculation with Verticillium. In particular, the abundance of root endophyte- and arbuscular mycorrhizal functional guilds was reduced significantly as a result of biofumigant and V. dahliae addition, whereas the abundance of saprotrophs increased significantly when both treatments were applied together. Alpha diversity analyses of fungi associated with roots indicated a significant increase in species richness following Verticillium inoculation, whereas the biofumigant alone or in the presence of V. dahliae resulted in no significant effect, suggesting that apparently some rare taxa may have been enriched/stimulated in the presence of the pathogen. Further investigations should reveal whether negative effects of biofumigation on potentially beneficial root associated endophytes and arbuscular mycorrhizal fungi are host genotype- or soil-dependent.

Phosphorus elevation erodes ectomycorrhizal community diversity and induces divergence of saprophytic community composition between vegetation types

Phosphorus (P) is a critical macronutrient that is essential for many life-sustaining processes. Despite decades of work on plant performance under P deficiency and the importance of microbes in ecosystem processes, little is known about how bacterial and fungal flora respond to P gradients and determine the vegetation health. In current study, we examined soil edaphic conditions and microbial communities in 39 untouched natural forests representing phosphorous deficient (Pp) and phosphorus rich (Pr) soils (due to naturally occurring phosphate rocks) in Yunnan Province, China. We also considered the effect of plant functional types by including the dominant tree species. Bacterial and fungal diversity was greater across the Pp sites compared with Pr sites. The relative abundance of Actinobacteria and Gemmatimonadetes was higher across Pp sites, while Chlamydiae and Verrucomicrobia showed the opposite pattern, with greater relative abundance across the Pr sites. Bacterial taxa that were observed in low P soils were more likely having oligotrophic life history strategies. Interestingly, ectomycorrhizal (ECM) fungal diversity was promoted in the Pp sites, indicating that the decreasing soil P concentration and the increasing host P demand foster stimulated the ECM species for hyphal soil exploration. Moreover, the high P level caused saprophytic fungi (SAP) to diverge, causing its enrichment only under Q. variabilis compared to low P soil, where there is no difference in relative abundance of SAP between the two tree species. This likely resulted in an enhanced decomposition process by SAP and elevation of soil properties (Carbon and Nitrogen) under Q. variabilis across the Pr sites. Taken together, our findings highlight the highly diverse microbiome in low P soils. The higher soil P caused shifts of fungal functional guilds, which likely influence tree growth and health (ECM), along with divergence of ecosystem services between tree functional types.

Dinotefuran alters Collembola-fungi-bacteria interactions that control mineralization of maize and soil organic carbon

Rare studies investigated influence of neonicotinoid insecticides on the whole soil biota including non-target invertebrates and microorganisms. And less is known about the consequent intervention on soil C processes. This study aimed to decipher Collembola-fungi-bacteria interactive effects on pathways of maize C translocation, combining isotopic tracer analysis of relevant compartments with high-throughput sequencing for bacterial and fungal genetic profiles. Dinotefuran was applied at 0 or 100 μg kg−1 (a simulating residual dosage) to microcosms containing soils, Collembola and 13C labelled maize. Dinotefuran drastically reduced the density and maize-derived biomass C of Collembola, while intensifying antagonistic associations between soil organisms, with flourishing growth of Ascomycota and Actinobacteria, e.g., Streptomyces. This led to higher soil organic C (SOC) mineralization (elevated by 9.8–10.5%) across soils, attributing to the shift in microbial taxonomic and functional guild, e.g., with the increased abundance of genes aligned to cytochrome P450. Maize decomposition was controlled by Collembola that primarily fed on maize, via grazing behavior that facilitated labile maize C preferred decomposers, e.g., Xanthomonadaceae. These findings elucidate the influence of minute dinotefuran on intra-linkages between biomes (Collembola, fungi and bacteria), and highlight such legacy effects on maize and SOC mineralization.

Taxonomic, phylogenetic and functional diversity of root-associated fungi in bromeliads: effects of host identity, life forms and nutritional modes.

Bromeliads represent a major component of neotropical forests and encompass a considerable diversity of life forms and nutritional modes. Bromeliads explore highly stressful habitats and root-associated fungi may play a crucial role in this, but the driving factors and variations in root-associated fungi remain largely unknown. We explored root-associated fungal communities in 17 bromeliad species and their variations linked to host identity, life forms and nutritional modes by using ITS1 gene-based high-throughput sequencing and by characterizing fungal functional guilds. We found a dual association of mycorrhizal and nonmycorrhizal fungi. The different species, life forms and nutritional modes among bromeliad hosts had fungal communities that differ in their taxonomic and functional composition. Specifically, roots of epiphytic bromeliads had more endophytic fungi and dark septate endophytes and fewer mycorrhizal fungi than terrestrial bromeliads and lithophytes. Our results contribute to a fundamental knowledge base on different fungal groups in previously undescribed Bromeliaceae. The diverse root-associated fungal communities in bromeliads may enhance plant fitness in both stressful and nutrient-poor environments and may give more flexibility to the plants to adapt to changing environmental conditions.

Effects of Rhododendron removal on soil bacterial and fungal communities in southern Appalachian forests

Rhododendron maximum, a native ericaceous evergreen shrub, is expanding in forests of the southern Appalachian region following eastern hemlock (Tsuga canadensis) mortality due to hemlock woolly adelgid (Adelges tsugae) infestations. The goal of our study was to examine soil microbial community responses to experimental R. maximum removal treatments. The experiment was implemented as a 2 × 2 factorial design, including two R. maximum canopy removal levels (cut vs. not cut) combined with two forest floor removal levels (burned vs. not burned). These treatments were designed as potential management strategies to facilitate hardwood tree establishment in forests that have experienced T. canadensis declines. We sampled soils after removals and characterized bacterial and fungal communities using amplicon sequencing. Shrub removal did not affect bacterial or fungal α diversity but did affect both bacterial and fungal community composition. Relative abundances of bacterial phyla and fungal classes exhibited no differences among R. maximum removal treatments. However, specific bacterial and fungal taxa that were responsive to R. maximum removal (i.e., differentially abundant sequences) did exhibit clear patterns at high taxonomic levels. Specifically, taxa that responded negatively to R. maximum removal were found primarily in two bacterial phyla (Proteobacteria and Bacteroidetes) and one fungal class (Archaeorhizomycetes) while positive responders were clustered in several other bacterial phyla (e.g., Actinobacteria, Planctomycetes, Cyanobacteria). Fungal functional guilds also responded to R. maximum removal, including negative responses of ericoid mycorrhizae and positive responses of arbuscular mycorrhizae and wood saprotrophs. Effects of R. maximum removal on soil microbial communities were minor overall, but clear effects on some key functional groups were evident (i.e., mycorrhizal fungi), suggesting that microbial responses to R. maximum removal may influence recovery of forests in the southern Appalachian region.

Volatile organic compound patterns predict fungal trophic mode and lifestyle

Fungi produce a wide variety of volatile organic compounds (VOCs), which play central roles in the initiation and regulation of fungal interactions. Here we introduce a global overview of fungal VOC patterns and chemical diversity across phylogenetic clades and trophic modes. The analysis is based on measurements of comprehensive VOC profiles of forty-three fungal species. Our data show that the VOC patterns can describe the phyla and the trophic mode of fungi. We show different levels of phenotypic integration (PI) for different chemical classes of VOCs within distinct functional guilds. Further computational analyses reveal that distinct VOC patterns can predict trophic modes, (non)symbiotic lifestyle, substrate-use and host-type of fungi. Thus, depending on trophic mode, either individual VOCs or more complex VOC patterns (i.e., chemical communication displays) may be ecologically important. Present results stress the ecological importance of VOCs and serve as prerequisite for more comprehensive VOCs-involving ecological studies.

Plant richness drives ant diversity in Eucalyptus‐dominated landscape on Brazilian savanna

AbstractThe conversion of natural areas into agricultural systems and silviculture is the greatest threat to biodiversity in tropical ecosystems such as the Brazilian savanna (Cerrado). This landscape transformation could lead to the loss of native species, including ants that cannot tolerate the new environment dominated by exotic plant species, such as Eucalyptus spp. The present study aims to investigate ant diversity and their functional groups to verify which vegetation and landscape variables explain their changes in a neglected formation of Cerrado (Campos Murundus) surrounded by Eucalyptus forests planted. We sampled ants in 29 sites, which presented a gradient of richness, average plant heights, and distances from Eucalyptus plantations and permanent protected areas (PPAs). We found 83 ant species from six functional guilds (arboreal, Camponotini, epigeic omnivorous, higher Attini, lower Attini and specialist predators). Plant richness best explained the diversity of ants. Higher distance from Eucalyptus plantations also positively explained the frequency of functional groups, whereas higher distance from the PPAs negatively explained the frequency of Camponotini species. Our study showed that vegetation (plant richness) and landscape variables help to understand ant diversity in a Eucalyptus‐dominated landscape. This reaffirms the importance of preserving the vegetation and their associate fauna in Campos Murundus by increasing the extent of conservation of this threatened biome.