Peter Kennedy

Peter Kennedy
University of Minnesota Twin Cities | UMN

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132
Publications
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Publications

Publications (132)
Article
Full-text available
The development of high‐throughput sequencing (HTS) technologies has greatly improved our capacity to identify fungi and unveil their ecological roles across a variety of ecosystems. Here we provide an overview of current best practices in metabarcoding analysis of fungal communities, from experimental design through molecular and computational ana...
Article
Associations between soil minerals and microbially-derived organic matter (often referred to as mineral-associated organic matter or MAOM) form a large pool of slowly cycling carbon (C). The rhizosphere, soil immediately adjacent to roots, is thought to control the spatial extent of MAOM formation because it is the dominant entry point of new C inp...
Preprint
Full-text available
The development of high-throughput sequencing (HTS) technologies has greatly improved our capacity to identify fungi and unveil their ecological roles across a variety of ecosystems. Here we provide an overview about current best practices in metabarcoding analysis of fungal communities, from experimental design through molecular and computational...
Article
Increasing temperature and decreasing precipitation has led to more frequent and extreme drought events in many regions throughout the world. In the western United States, multi‐year drought events have led to widespread plant mortality and extreme wildfires (Asner et al. 2016, Pickrell and Pennisi 2020). Communities of ectomycorrhizal fungi (EMF)...
Article
Full-text available
Purpose A better knowledge of how deadwood decomposes is critical for accurately characterizing carbon and nutrient cycling in forests. Fungi dominate this decomposition process, but we still have limited understanding of fungal community structuring that ultimately controls the fate of wood decomposition. This is particularly true in tropical ecos...
Article
Dead fungal mycelium (necromass) represents a critical component of soil carbon (C) and nutrient cycles. Assessing how the microbial communities associated with decomposing fungal necromass change as global temperatures rise will help in determining how these belowground organic matter inputs contribute to ecosystem responses. ●In this study, we ch...
Article
Full-text available
Suillus is among the best-known examples of an ectomycorrhizal (ECM) fungal genus that demonstrates a high degree of host specificity. Currently recognized host genera of Suillus include Larix, Pinus, and Pseudotsuga, which all belong to the pinoid clade of the family Pinaceae. Intriguingly, Suillus sporocarps have been sporadically collected in fo...
Article
Full-text available
Recent studies have highlighted that dead fungal mycelium represents an important fraction of soil carbon (C) and nitrogen (N) inputs and stocks. Consequently, identifying the microbial communities and the ecological factors that govern the decomposition of fungal necromass will provide critical insight into how fungal organic matter (OM) affects f...
Article
While there has been significant progress characterizing the ‘symbiotic tool kit’ of ectomycorrhizal (ECM) fungi, how host specificity may be encoded into ECM fungal genomes remains poorly understood. We conducted a comparative genomic analysis of ECM fungal host specialists and generalists, focusing on the specialist genus Suillus. Global analyses...
Article
1. Fungi represent a rapidly cycling pool of carbon (C) and nitrogen (N) in soils. Understanding of how this pool impacts soil nutrient availability and organic matter fluxes is hindered by uncertainty regarding the dynamics and drivers of fungal necromass decomposition. 2. Here we assessed the generality of common models for predicting mass loss d...
Article
Hurricanes impact forests by damaging trees and altering multiple ecosystem functions. As such, predicting which individuals are likely to be most affected has crucial economic importance as well as conservation value. Tree stem-inhabiting fungal communities, notably rot-causing agents, have been mentioned as a potential factor of tree predispositi...
Article
Full-text available
Two common ecological assumptions are that host generalist and rare species are poorer competitors relative to host specialist and more abundant counterparts. While these assumptions have received considerable study in both plant and animals, how they apply to ectomycorrhizal fungi remains largely unknown. To investigate how interspecific competiti...
Article
Full-text available
Rationale: Fine roots mediate belowground resource acquisition, yet understanding of how fine-root functional traits vary along environmental gradients, within branching orders, and across phylogenetic scales remains limited. Methods: Morphological and architectural fine-root traits were measured on individual root orders of 20 oak species (genu...
Preprint
Full-text available
Two common ecological assumptions are that host generalist and rare species are poorer competitors relative to host specialist and more abundant counterparts. While these assumptions have received considerable study in both plant and animals, how they apply to ectomycorrhizal fungi remains largely unknown. To investigate how interspecific competiti...
Article
Interactions between symbiotic ectomycorrhizal (EM) and free‐living saprotrophs can result in significant deceleration of leaf litter decomposition. While this phenomenon is widely cited, its generality remains unclear, as both the direction and magnitude of EM fungal effects on leaf litter decomposition have been shown to vary among studies. Here...
Article
While the relationship between plant and microbial diversity has been well studied in grasslands, less is known about similar relationships in forests, especially for obligately symbiotic arbuscular mycorrhizal (AM) fungi. To assess the effect of varying tree diversity on microbial alpha- and beta-diversity, we sampled soil from plots in a high-den...
Preprint
Full-text available
Interactions between symbiotic ectomycorrhizal (EM) and free-living saprotrophs can result in significant deceleration of leaf litter decomposition. While this phenomenon is widely cited, its generality remains unclear, as both the direction and magnitude of EM fungal effects on leaf litter decomposition have been shown to vary among studies. Here...
Article
Full-text available
Fine root decomposition constitutes a critical yet poorly understood flux of carbon and nutrients in terrestrial ecosystems. Here, we present the first large‐scale synthesis of species trait effects on the early stages of fine root decomposition at both global and local scales. Based on decomposition rates for 279 plant species across 105 studies a...
Article
Full-text available
Despite being a significant input into soil carbon pools of many high‐latitude ecosystems, little is known about the effects of climate change on the turnover of mycorrhizal fungal necromass. Here, we present results from the first experiment examining the effects of climate change on the long‐term decomposition of mycorrhizal necromass, utilising...
Article
Human-driven increases in bioavailable nitrogen over the last century have revealed the critical need to understand how nitrogen availability influences terrestrial ecosystems. In contrast to widespread evidence that increasing inorganic nitrogen strongly influences the diversity and composition of plant and microbial communities, the effect of org...
Article
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Despite covering vast areas of boreal North America, the ecological factors structuring mycorrhizal fungal communities in peatland forests are relatively poorly understood. To assess how these communities vary by age (younger vs. mature), habitat (fen vs. bog), and host (conifer trees vs. ericaceous shrub), we sampled the roots of two canopy trees...
Article
Full-text available
Mycorrhizal fungal necromass is increasingly recognized as an important contributor to soil organic carbon pools, particularly in forest ecosystems. While its decomposition rate is primarily determined by biochemical composition, how traits such as melanin content affect the structure of necromass decomposer communities remains poorly understood. T...
Article
Despite the importance of ectomycorrhizal (ECM) fungi in forest ecosystems, knowledge about the ecological and co-evolutionary mechanisms underlying ECM host associations remains limited. Using a widely distributed group of ECM fungi known to form tight associations with trees in the family Pinaceae, we characterized host specificity among three un...
Article
This article is a Commentary on Tedersoo et al., 217: 1370–1385.
Article
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Analytical methods can offer insights into the structure of biological networks, but mechanisms that determine the structure of these networks remain unclear. We conducted a synthesis based on 111 previously published datasets to assess a range of ecological and evolutionary mechanisms that may influence the plant-associated fungal interaction netw...
Article
Despite the central role of saprotrophic fungi in wood decomposition and terrestrial carbon cycling, the diversity and functioning of wood endophytes (i.e., fungi that asymptomatically colonize living plant tissue) on decay remains poorly understood. 2.In a four-year field experiment in a boreal forest in the upper midwestern United States, we inve...
Article
Full-text available
Carbon allocation demands from root-nodulating nitrogen-fixing bacteria (NFB) can modulate the host plant's chemical phenotype, with strong bottom-up effects on herbivores. In contrast to well-studied rhizobia, the effects of other important NFB on plant chemistry and herbivory are much less understood. Here, combining field surveys in the Oregon C...
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
Rising temperatures associated with climate change have been shown to negatively affect the photosynthetic rates of boreal forest tree saplings at their southern range limits. To quantify the responses of ectomycorrhizal (EM) fungal communities associated with poorly performing hosts, we sampled the roots of Betula papyrifera and Abies balsamea sap...
Article
Priority effects among wood decomposers have been demonstrated by manipulating fungal assembly history via inoculations in dead wood and then tracking community development using DNA sequencing. Individual wood-degrading fungi have been shown, however, to initiate decay after having colonized living trees as endophytes. 2.To track these ‘upstream’...
Article
Full-text available
Fungi represent a large proportion of the genetic diversity on Earth and fungal activity influences the structure of plant and animal communities, as well as rates of ecosystem processes. Large-scale DNA-sequencing datasets are beginning to reveal the dimensions of fungal biodiversity, which seem to be fundamentally different to bacteria, plants an...
Article
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Exploring the link between above- and belowground biodiversity has been a major theme of recent ecological research, due in large part to the increasingly well-recognized role that soil microorganisms play in driving plant community processes. In this study, we utilized a field-based tree experiment in Minnesota, USA to assess the effect of changes...
Article
Full-text available
In temperate and boreal forest ecosystems, nitrogen (N) limitation on tree metabolism is alleviated by ectomycorrhizal (ECM) fungi. As forest soils age, the primary source of N in soil switches from inorganic (NH4 (+), NO3 (-)) to organic (mostly proteins). It has been hypothesized that ECM adapt to the most common N source in their environment, wh...
Chapter
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While the dominant ectomycorrhizal (ECM) fungi in most temperate and tropical forests have low host specificity , a commonly cited exception to this pattern is the ECM fungal community associated with the host genus Alnus. In this chapter, we discuss multiple hypotheses that have been put forth to explain the specificity of the Alnus ECM symbiosis...
Article
I. II. III. IV. V. VI. VII. VIII. References SUMMARY: In forest ecosystems, ectomycorrhizal and saprotrophic fungi play a central role in the breakdown of soil organic matter (SOM). Competition between these two fungal guilds has long been hypothesized to lead to suppression of decomposition rates, a phenomenon known as the 'Gadgil effect'. In this...
Article
Soil depth partitioning is thought to promote the diversity of ectomycorrhizal (EM) fungal communities, but little is known about whether it is controlled by abiotic or biotic factors.In three bioassay experiments, we tested the role of vertical soil heterogeneity in determining the distributions and competitive outcomes of the EM sister species Rh...
Article
Full-text available
Fungi typically live in highly diverse communities composed of multiple ecological guilds. Although high-throughput sequencing has greatly increased the ability to quantify the diversity of fungi in environmental samples, researchers currently lack a simple and consistent way to sort large sequence pools into ecologically meaningful categories. We...
Article
Full-text available
Next generation fungal amplicon sequencing is being used with increasing frequency to study fungal diversity in various ecosystems; however, the influence of sample preparation on the characterization of fungal community is poorly understood. We investigated the effects of four procedural modifications to library preparation for high-throughput seq...
Article
AimIt has been proposed that co-invasion with ectomycorrhizal (EM) fungi is a common mechanism by which non-indigenous trees overcome symbiont limitation, yet virtually all prior evidence has come from a single plant family, the Pinaceae. We tested the co-invasion hypothesis by examining the EM fungal communities associated with a specialized host,...
Article
Full-text available
A number of recent studies suggest that interspecific competition plays a key role in determining the structure of ectomycorrhizal (ECM) fungal communities. Despite this growing consensus, there has been limited study of ECM fungal community dynamics in abiotically stressful environments, which are often dominated by positive rather than antagonist...
Conference Paper
Full-text available
Background/Question/Methods “Enemy escape” is often cited as a key biotic contributor to the invasion success of non-indigenous species, but the presence or absence of specialized mutualists may also play a significant role in determining invasional outcomes. This study examines how mutualistic specificity is influencing the invasion of two Europ...
Article
The ectomycorrhizal (ECM) fungal communities associated with the host genus Alnus have been widely noted for their low richness and high proportion of host-specific species, but the processes underlying their atypical structure remain poorly understood. In this study, we investigated whether the high acidity and nitrate concentrations characteristi...
Article
Full-text available
Rhizopogon (Boletales) represents a model genus for ecological studies of ectomycorrhizal fungi, but the identification of species in subgenus Villosuli section Villosuli has long been challenging due to variation in taxonomically informative morphological characters. Here we re-examine species concepts in this section using data from nuclear ribos...
Article
Much of the macroecological information about microorganisms is confounded by the lack of standardized methodology, paucity of metadata and sampling effect of a particular substrate or interacting host taxa. This study aims to disentangle the relative effects of biological, geographical and edaphic variables on the distribution of Alnus-associated...
Article
Host identity has been recognized as a key determinant of the structure of ectomycorrhizal (ECM) fungal communities, but the importance of neighboring ECM hosts is less well understood. To investigate the relative importance of host and neighborhood effects, we examined the ECM fungal communities associated with Alnus rhombifolia, a host of specifi...