Gregory S Gilbert

University of California, Santa Cruz | UCSC · Department of Environmental Studies

Novel methods for sampling and characterizing biodiversity hold great promise for re-evaluating patterns of life across the planet. The sampling of airborne spores with a cyclone sampler, and the sequencing of their DNA, have been suggested as an efficient and well-calibrated tool for surveying fungal diversity across various environments. Here we...

The future trajectory of global forests is closely intertwined with tree demography, and a major fundamental goal in ecology is to understand the key mechanisms governing spatio‐temporal patterns in tree population dynamics. While previous research has made substantial progress in identifying the mechanisms individually, their relative importance a...

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)³. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species co...

One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fung...

The benefits of masting (volatile, quasi-synchronous seed production at lagged intervals) include satiation of seed predators, but these benefits come with a cost to mutualist pollen and seed dispersers. If the evolution of masting represents a balance between these benefits and costs, we expect mast avoidance in species that are heavily reliant on...

Wildland conservation efforts require accurate maps of plant species distribution across large spatial scales. High-resolution species mapping is difficult in diverse, dense plant communities, where extensive ground-based surveys are labor-intensive and risk damaging sensitive flora. High-resolution satellite imagery is available at scales needed f...

Invasive C4 grasses can inhibit the natural regeneration of secondary forest in tropical landscapes after the cessation of intensive use for grazing and agriculture. In Panama, invasive Saccharum spontaneum forms dense stands that require active management to re-establish forest successional processes. In this region, restoration strategies typical...

Understanding the symbiosis between plants and pathogenic microbes is at the core of effective disease management for crops and managed forests. At the same time, plant–pathogen interactions comprise a wonderfully diverse set of ecological relationships that are powerful and yet so commonplace that they often go unnoticed. Ecologists and evolutiona...

Plants are primary producers, converting atmospheric carbon dioxide into sugars through photosynthesis. Plant pathogens take advantage of this energy source, and because the plant immune system is not comprised of specialized cells or organs, every plant cell must defend itself. The plant vascular system moves water and mineral nutrients through xy...

Plant pathogens affect their hosts in diverse ways. Some deprive the host of carbon by parasitizing it or by reducing photosynthetic tissue, and some restrict access to water by disrupting the vascular system; either can slow the growth of the plant and reduce host fecundity. Other pathogens directly kill parts or all of the plant, and still other...

Fungi are the most abundant and diverse of plant pathogens. Filamentous fungi grow as long tubes called hyphae that form mycelial networks. They obtain nutrition as osmotrophic heterotrophs, secreting enzymes into the substrate that surrounds them, then absorbing simpler compounds rich in carbon and nutrients. Fungi reproduce asexually and sexually...

Evolutionary biology includes microevolution, which incorporates genetics into the study of traits, and macroevolution, which focuses on patterns of traits across the history of life. Evolution proceeds via both random changes in allele frequency through genetic drift and non-random changes through natural selection. Genetic drift is important in s...

Plants lack antibody-based immune systems, but they do have a robust system of defenses against pathogens. Constitutive defenses are a broad array of constitutively-produced physical structures and chemical compounds that protect most plants from infection by most pathogens. The three major groups of plant chemical defenses are phenolics, terpenoid...

Viruses are non-cellular pathogens. Plant viruses are obligate parasites of plant host cells that rely on their host for transcription and replication. Viruses disrupt the growth of plants by dominating host resources for transcription and translation, and sometimes by manipulating host cellular processes. There are six groups of plant viruses, cla...

Population ecology concerns the structure and numerical dynamics of populations; it uses mathematical models to understand patterns in groups of organisms and their interactions. In plant populations, the spread of disease through time generally falls into two types: monocyclic and polycyclic. For monocyclic diseases, plants are infected from prima...

Oomycetes are in the Stramenopiles group of protists and many are aggressive plant pathogens. Oomycetes grow as coenocytic hyphae creating mycelial networks. They can reproduce through long-lasting sexual oospores or asexual chlamydospores. Sometimes called water molds, when provided with abundant moisture they can produce sporangia that release mo...

Plant-associated bacteria are heterotrophic prokaryotes, forming a diversity of types of symbioses with plants. Bacteria reproduce through binary fission, and they achieve large population sizes very rapidly through exponential growth. Bacteria often grow in biofilms on plants or in soil, incorporating extracellular polysaccharides as structure. Qu...

The assemblage of microbes that inhabit the plant as symbionts comprise the plant microbiome. The activities of plant roots have a dramatic effect on the density and composition of bacteria and fungi growing around them, known as the rhizosphere effect. Plant-microbe and microbe-microbe interactions in the rhizosphere have large impacts on plant he...

Accelerating patterns of land-use change, air pollution, global trade, and climate change all contribute to changes in plant-pathogen interactions and the emergence of novel infectious plant diseases. Land conversion to agriculture has led to new encounters between crops and local pathogens, leading to the emergence of novel diseases through spillo...

Management of plant diseases relies on two general strategies: avoidance and control. Avoidance tactics involve evasion of pathogens by not planting susceptible crops in areas where virulent pathogens are present, and exclusion of pathogens through phytosanitary practices. Control tactics rely on planting crop cultivars with genetic and physiologic...

Plant disease ecologists rely on a wide array of technical skills to diagnose and study plant disease. Disease intensity can be measured as the prevalence of disease across a host population or the severity of disease in individual plants. Sampling plans must consider both precision and accuracy. Plant diseases are diagnosed through the combination...

Community ecology is the study of interactions among species and the resulting diversity, composition, and structure of communities of organisms. Diversity is comprised of the number, types and relative abundances of species in the community. Most communities have a few common species and many rare ones. Within-community diversity is called alpha d...

Spatial ecology is the study of spatial structure in populations and communities and the processes that create that structure. Disease spreads through plant populations when propagules of pathogens disperse from one plant to another. Propagules often disperse passively, moving via currents of air or water. However, some motile pathogens disperse ac...

Two groups of larger organisms cause disease on plants: plants and nematodes. Parasitic plants may be holoparasites that depend on their host plants for water, nutrients, and sugars, while hemiparasites tap into xylem and exploit their hosts for water only. Mistletoes, dodder, and witchweeds are well-known examples. Parasitic plants evolved indepen...

Plant disease is the outcome of antagonistic symbiotic interactions between pathogenic microorganisms and susceptible hosts, contingent on environmental conditions that are favorable for infection and symptom development. Plant-microbe symbioses can range from mutualistic to parasitic. The ecological outcomes of plant-microbe interactions are the p...

Understanding the symbiosis between plants and pathogenic microbes is at the core of effective disease management for crops and managed forests. At the same time, plant–pathogen interactions comprise a wonderfully diverse set of ecological relationships that are powerful and yet so commonplace that they often go unnoticed. Ecologists and evolutiona...

Understanding the symbiosis between plants and pathogenic microbes is at the core of effective disease management for crops and managed forests. At the same time, plant–pathogen interactions comprise a wonderfully diverse set of ecological relationships that are powerful and yet so commonplace that they often go unnoticed. Ecologists and evolutiona...

Understanding the symbiosis between plants and pathogenic microbes is at the core of effective disease management for crops and managed forests. At the same time, plant–pathogen interactions comprise a wonderfully diverse set of ecological relationships that are powerful and yet so commonplace that they often go unnoticed. Ecologists and evolutiona...

Understanding the symbiosis between plants and pathogenic microbes is at the core of effective disease management for crops and managed forests. At the same time, plant–pathogen interactions comprise a wonderfully diverse set of ecological relationships that are powerful and yet so commonplace that they often go unnoticed. Ecologists and evolutiona...

Aim Our understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whethe...

Plant diseases cause hundreds of billions of dollars in global crop production each year. Many plant diseases develop when pathogens germinate and proliferate in the fertile environment of excess water on the leaf surfaces. Accurate measurement of how long a leaf stays wet is important to assess the risk of pathogen infestation and decide on approp...

Concern over microbial contamination limits the adoption of home production of sprouts as a nutritious and sustainable food. Simple, accessible approaches to seed disinfection could support safe home seed sprouting. Here, we quantify bacterial and fungal contamination of seeds of 14 plant cultivars sold for home sprout production and test a range o...

Aim: Global forests and their structural and functional features are shaped by many mechanisms that impact tree vital rates. Although many studies have tried to quantify how specific mechanisms influence vital rates, their relative importance among forests remains unclear. We aimed to assess the patterns of variation in vital rates among species an...

Plant pathogens are often hypothesized to promote species coexistence by generating conspecific negative density dependence (CNDD). However, the relative importance of fungal versus oomycete pathogens in maintaining plant species coexistence and community composition remains unresolved, despite their recognized effects on plant performance. Here, w...

The phylogenetic distance between species often predicts differences in ecologically important traits. The phylogenetic diversity and structure of biological communities can inform our understanding of the processes that shape those communities, and there is a well-developed framework for comparing phylogenetic structures of communities. However, p...

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundat...

Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250‐fold increase in seed abundance from cold‐dry to warm‐wet climates, driven primarily by...

This paper examines how journalists use discursive strategies when covering the complex issue of climate change in The Mercury News, a large regional U.S.A. newspaper in California, a state deeply impacted by this problem. Quantitative content analysis of published texts and semi-structured interviews of journalists uncovered common use of formativ...

Significance Suitable habitats for forest trees may be shifting fast with recent climate change. Studies tracking the shift in suitable habitat for forests have been inconclusive, in part because responses in tree fecundity and seedling establishment can diverge. Analysis of both components at a continental scale reveals a poleward migration of nor...

Allometric equations for calculation of tree above‐ground biomass ( AGB ) form the basis for estimates of forest carbon storage and exchange with the atmosphere. While standard models exist to calculate forest biomass across the tropics, we lack a standardized tool for computing AGB across boreal and temperate regions that comprise the global extra...

Most desert plants form symbiotic relationships with arbuscular mycorrhizal fungi (AMF), yet fungal identity and impacts on host plants remain largely unknown. Despite widespread recognition of the importance of AMF relationships for plant functioning, we do not know how fungal community structure changes across a desert climate gradient, nor the i...

Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current esti...

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to t...

Mycorrhizae alter global patterns of CO2 fertilization, carbon storage, and elemental cycling, yet knowledge of their global distributions is currently limited by the availability of forest inventory data. Here, we show that maps of tree-mycorrhizal associations (hereafter “mycorrhizal maps”) can be improved by the novel technology of imaging spect...

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-22025-2

Indirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here...

Recent studies suggest that the mycorrhizal type associated with tree species is an important trait influencing ecological processes such as response to environmental conditions and conspecific negative density dependence (CNDD). However, we lack a general understanding of how tree mycorrhizal type influences CNDD strength and the resulting pattern...

The phylogenetic signal of transmissibility (competence) and attack severity among hosts of generalist pests is poorly understood. In this study, we examined the phylogenetic effects on hosts differentially affected by an emergent generalist beetle‐pathogen complex in California and South Africa. Host types (non‐competent, competent, and killed‐com...

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimens...

Fungal communities are structured across time and space by abiotic and biotic factors. We use amplicon-based genetic sequencing techniques to identify unculturable and culturable fungi in airborne spore assemblages across a vegetation mosaic and over the course of a rainy season in coastal California, USA. We found that the assemblages of fungal sp...

Biodiversity is thought to help regulate the impacts of disease through the dilution effect, where biodiversity among potential host species helps limit the impacts of pathogens. However, our knowledge is fragmentary about the direction and magnitude of the effects of plant species richness on disease impact. Here, we gathered data from 145 compari...

The plant economics spectrum proposes that ecological traits are functionally coordinated and adapt along environmental gradients. However, empirical evidence is mixed about whether aboveground and root traits are consistently linked and which environmental factors drive functional responses. Here we measure the strength of relationships between ab...

Next-generation sequencing (NGS) of amplicons is used in a wide variety of contexts. In many cases, NGS amplicon sequencing remains overly expensive and inflexible, with library preparation strategies relying upon the fusion of locus-specific primers to full-length adapter sequences with a single identifying sequence or ligating adapters onto PCR p...

The relationship between plant diversity and productivity and the mechanisms underpinning that relationship remain poorly resolved in species-rich forests. We combined extensive field observations and experimental manipulations in a subtropical forest to test how species richness (SR) and phylogenetic diversity (PD) interact with putative root-asso...

Next-generation sequencing (NGS) of amplicons is used in a wide variety of contexts. Most NGS amplicon sequencing remains overly expensive and inflexible, with library preparation strategies relying upon the fusion of locus-specific primers to full-length adapter sequences with a single identifying sequence or ligating adapters onto PCR products. I...

Reforestation is challenging when timber harvested areas have been degraded, invaded by nonnative species, or are of marginal suitability to begin with. Conifers form mutualistic partnerships with ectomycorrhizal fungi (EMF) to obtain greater access to soil resources, and these partnerships may be especially important in degraded areas. However, ti...

Plant pathogens reduce the performance of their hosts and therefore may contribute to ecological mechanisms of coexistence. In Chesson’s framework, pathogens contribute to stabilizing mechanisms when they intensify negative intraspecific interactions, such as density‐dependent disease. Additionally, pathogens contribute to equalizing mechanisms whe...

Changing climate patterns can affect the geographic distribution of species through effects on species interactions. Iconic Joshua trees are limited to a narrow range of climate conditions, and climate change is expected to shift suitable habitat to higher elevations and latitudes than their current geographic distribution. As such, the survival of...

Aim To examine the contribution of large‐diameter trees to biomass, stand structure, and species richness across forest biomes. Location Global. Time period Early 21st century. Major taxa studied Woody plants. Methods We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 t...

Social factors play a critical role in almost every conservation problem. There is a pressing need for conservation researchers and practitioners to understand both the ecological and human dimensions of their systems in order for projects to be successful. At the same time, many conservation professionals come from a natural science background wit...

The abundance of airborne fungal spores in agricultural and urban settings increases with greater air temperature, relative humidity, or precipitation. The same meteorological factors that affect temporal patterns in spore abundance in managed environments also vary spatially across natural habitats in association with differences in vegetation str...

[This corrects the article DOI: 10.1371/journal.pone.0156913.].

Premise of the study Field methodology and image analysis protocols using acoustic tomography were developed and evaluated as a tool to estimate the amount of internal decay and damage of living trees, with special attention to tropical rainforest trees with irregular trunk shapes. Methods and Results Living trunks of a diversity of tree species i...

Species introductions are a dominant component of biodiversity change but are not explicitly included in most discussions of biodiversity-disease relationships. This is a major oversight given the multitude of effects that introduced species have on both parasitism and native hosts. Drawing on both animal and plant systems, we review the competing...

Recent studies have detected phylogenetic signals in pathogen–host networks for both soil-borne and leaf-infecting fungi, suggesting that pathogenic fungi may track or coevolve with their preferred hosts. However, a phylogenetically concordant relationship between multiple hosts and multiple fungi in has rarely been investigated. Using next-generat...

Negative density-dependent seedling mortality has been widely detected in tropical, subtropical and temperate forests, with soil pathogens as a major driver. Here we investigated how host density affects the composition of soil pathogen communities and consequently influences the strength of plant-soil feedbacks. In field censuses of six 1-ha perma...

One approach in forest restoration is to plant trees that will establish an initial canopy to promote forest recovery through the colonization of other species. The identity of the planted tree affects which species are able to recruit in its understory. Here we evaluate the phylogenetic structure of young understory plant communities recruiting be...

An explicit phylogenetic perspective provides useful tools for phytopathology and plant disease ecology because the traits of both plants and microbes are shaped by their evolutionary histories. We present brief primers on phylogenetic signal and the analytical tools of phylogenetic ecology. We review the literature and find abundant evidence of ph...

Studies of forest dynamics plots (FDPs) have revealed a variety of negative density-dependent (NDD) demographic interactions, especially among conspecific trees. These interactions can affect growth rate, recruitment and mortality, and they play a central role in the maintenance of species diversity in these complex ecosystems. Here we use an equal...

Text A, Text B, Figs A-F. (DOCX)

Models are simplified representations of more complex systems that help scientists structure the knowledge they acquire. As such, they are ubiquitous and invaluable in scientific research and communication. Because science education strives to make classroom activities more closely reflect science in practice, models have become integral teaching a...

Pathogens play an important part in shaping the structure and dynamics of natural communities, because species are not affected by them equally. A shared goal of ecology and epidemiology is to predict when a species is most vulnerable to disease. A leading hypothesis asserts that the impact of disease should increase with host abundance, producing...

The host ranges of plant pathogens and herbivores are phylogenetically constrained, so that closely related plant species are more likely to share pests and pathogens. Here we conducted a reanalysis of data from published experimental studies to test whether the severity of host-enemy interactions follows a similar phylogenetic signal. The impact o...

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characteriz...

One approach in forest restoration is to plant trees that will establish an initial canopy to promote forest recovery through natural recruitment of other species. Here we evaluate the patterns of either phylogenetic overdispersion or phylogenetic clustering on community assembly beneath seven different single-species tree plantations. We expected...

One approach in forest restoration is to plant trees that will establish an initial canopy to promote forest recovery through natural recruitment of other species. Here we evaluate the patterns of either phylogenetic overdispersion or phylogenetic clustering on community assembly beneath seven different single-species tree plantations. We expected...

Background/Question/Methods Rare host species are expected to suffer less damage from pathogens and pests than common hosts. This rare-species advantage is a key feature of hypotheses that explain how pathogens can help maintain diversity (e.g., Janzen-Connell hypothesis) or regulate invasions (e.g., Escape from Natural Enemies hypothesis). Howev...

Recent experiments support the long-standing hypothesis that Common Cuckoos (Cuculus canorus) are mimics of Eurasian Sparrowhawks (Accipiter nisus). Additional experiments further suggest that mimicry benefits the cuckoos by reducing the intensity of mobbing they suffer near host nests, at least in some host populations, potentially increasing thei...

Enrichment planting within established plantations or secondary forests is a common strategy to enhance forest recovery, given that later successional forest species tend to have low dispersal and limited recruitment into these sites. It is difficult, however, to predict how species of seedlings will perform when planted under different overstory s...

In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak-dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic u...

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Di...

Forest restoration uses active management to re-establish natural forest habitat after disturbance. However, competition from early successional species, often aggressively invasive exotic plant species, can inhibit tree establishment and forest regeneration. Ideally, restoration ecologists can plant native tree species that not only establish and...