Heidy Schimann

Heidy Schimann
French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Ecologie des Forêts de Guyane (ECOFOG)

PhD

About

60
Publications
15,680
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1,428
Citations

Publications

Publications (60)
Article
Plant-associated microorganisms have shown to aid plants in coping with drought. However, the underlying mechanisms are poorly understood and there is uncertainty regarding which microbial taxa and functions are mostly involved. We explored these issues in Neotropical rainforests and identified foliar microorganisms that may play a role in drought...
Article
Full-text available
Heteroblastic variations among leaf traits is a well-known process, especially in bromeliad species that show abrupt changes, but little effort was directed to test whether comparable ontogenetic variation occurs among root traits and their fungal partners. Usually considered for their mechanical role, roots of bromeliads may also play a role in re...
Preprint
Bacterial phyllosphere communities play a key role in the fitness of plants. Understanding the factors and mechanisms shaping them is necessary to predict how trees would respond to a variety of stresses or disturbances. In tropical forests, the steep vertical gradients in light, rainfall or temperature within the canopy are likely to drive the ass...
Article
Full-text available
The increasing severity and frequency of natural disturbances requires a better understanding of their effects on all compartments of biodiversity. In Northern Fennoscandia, recent large-scale moth outbreaks have led to an abrupt change in plant communities from birch forests dominated by dwarf shrubs to grass-dominated systems. However, the indire...
Article
Full-text available
Urban expansion and associated habitat transformation drives shifts in biodiversity, with declines in taxonomic and functional diversity. Forests fragments within urban landscapes offer a number of ecosystem services, and help to maintain biodiversity and ecosystem functions. Here, we focus on a tropical forest environment, and on the soil biota. U...
Article
Full-text available
Purpose of Review Forest research has shown for a long time that microorganisms influence tree-insect interactions, but the complexity of microbial communities, as well as the holobiont nature of both trees and insect herbivores, has only recently been taken fully into account by forest entomologists and ecologists. In this article, we review recen...
Article
Premise: Studying the organization of functional traits in plant leaves and stems has revealed notable patterns linking function and form; however, evidence of similarly robust organization in root tissues remains controversial. We posit that anatomical traits in roots can provide insight on the overall organization of the root system. We hypothes...
Article
Full-text available
Despite their recognized essential role in soil, earthworms in tropical environments are still understudied. The aim of this study was to re-evaluate the diversity at the regional scale, as well as to investigate the environmental and spatial drivers of earthworm communities. We sampled earthworm communities across a range of habitats at six locali...
Article
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 but their driving factors and variations in root‐associated fungi remain largely unknown. ⦁We explored root‐associate...
Preprint
Full-text available
The increasing severity and frequency of natural disturbances requires a better understanding of their effects on all compartments of biodiversity. In Northern Fennoscandia, recent large-scale moth outbreaks have led to an abrupt change in plant communities from birch forests dominated by dwarf shrubs to grass-dominated systems. However, the indire...
Preprint
Purpose of review Forest research has shown for a long time that microorganisms influence tree-insect interactions, but the complexity of microbial communities, as well as the holobiont nature of both trees and insect herbivores, have only recently been taken fully into account by forest entomologists and ecologists. In this article, we review rece...
Preprint
Despite their recognized essential role in soil, earthworms in tropical environments are still understudied. The aim of this study was to re-evaluate the diversity at the regional scale, as well as to investigate the environmental and spatial drivers of earthworm communities. We sampled earthworm communities across a range of habitats at six locati...
Article
Full-text available
The genus Phytophthora represents a group of plant pathogens with broad global distribution. The majority of them causes collar and root‐rot of diverse plant species. Little is known about Phytophthora communities in forest ecosystems, especially in Neotropical forests where natural enemies could maintain the huge plant diversity via negative densi...
Chapter
The rainforests of the Neotropics shelter a vast diversity of plant, animal and microscopic species that provide critical ecosystem goods and services for both local and worldwide populations. These environments face a major crisis due to increased deforestation, pollution, and climate change, emphasizing the need for more effective conservation ef...
Article
en The influence exerted by tree communities, topography, and soil chemistry on the assembly of macrofungal communities remains poorly understood, especially in highly diverse tropical forests. Here, we used a large dataset that combines inventories of macrofungal Basidiomycetes fruiting bodies, tree species composition, and measurements for 16 soi...
Book
The rainforests of the Neotropics shelter a vast diversity of plant, animal and microscopic species that provide critical ecosystem goods and services for both local and worldwide populations. These environments face a major crisis due to increased deforestation, pollution, and climate change, emphasizing the need for more effective conservation ef...
Article
Full-text available
High‐throughput sequencing of amplicons from environmental DNA samples permits rapid, standardized and comprehensive biodiversity assessments. However, retrieving and interpreting the structure of such datasets requires efficient methods for dimensionality reduction. Latent Dirichlet Allocation (LDA) can be used to decompose environmental DNA sampl...
Article
Full-text available
In Amazonia, the knowledge about Fungi remains patchy and biased towards accessible sites. This is particularly the case in French Guiana where the existing collections have been confined to few coastal localities. Here, we aimed at filling the gaps of knowledge in undersampled areas of this region, particularly focusing on the Basidiomycota. From...
Article
Full-text available
Little is known regarding how trophic interactions shape community assembly in tropical forests. Here we assess multi-taxonomic community assembly rules using a rare standardized coordinated inventory comprising exhaustive surveys of five highly-diverse taxonomic groups exerting key ecological functions: trees, fungi, earthworms, ants and spiders....
Article
Full-text available
Tropical forests shelter an unparalleled biological diversity. The relative influence of environmental selection (i.e. abiotic conditions, biotic interactions) and stochastic‐distance dependent neutral processes (i.e. demography, dispersal) in shaping communities has been extensively studied for various organisms, but has rarely been explored acros...
Article
A revision of Resinicium collections (Basidiomycota, Hymenochaetales) from French Guiana and French West Indies is provided, and a new species, Resinicium grandisporum sp. nov., supported by morphological as well as phylogenetic analyses based on ITS rDNA sequences, is described and illustrated. An updated key of the genus Resinicium is also provid...
Article
A revision of Resinicium collections (Basidiomycota, Hymenochaetales) from French Guiana and French West Indies is provided, and a new species, Resinicium grandisporum sp. nov., supported by morphological as well as phylogenetic analyses based on ITS rDNA sequences, is described and illustrated. An updated key of the genus Resinicium is also provid...
Preprint
Full-text available
The relative influence of deterministic niche-based (i.e. abiotic conditions, biotic interactions) and stochastic-distance dependent neutral processes (i.e. demography, dispersal) in shaping communities has been extensively studied for various organisms, but is far less explored jointly across the tree of life, in particular in soil environments. H...
Article
Full-text available
The VIIIth Brazilian Mycological Congress, held in Florianópolis (Brazil) in October 2016, was organized by the Universidade Federal de Santa Catarina and brought together more than 1000 scientists of 20 nationalities, which illustrates the dynamism of South American mycology, in many fields. One of the major take-home messages, amongst many resear...
Article
Full-text available
The patterns of the distribution of fungal species and their potential interactions with trees remain understudied in Neotropical rainforests, which harbor more than 16,000 tree species, mostly dominated by endomycorrhizal trees. Our hypothesis was that tree species shape the non-mycorrhizal fun- gal assemblages in soil and litter and that the dive...
Article
The patterns of the distribution of fungal species and their potential interactions with trees remain understudied in Neotropical rainforests, which harbor more than 16,000 tree species, mostly dominated by endomycorrhizal trees. Our hypothesis was that tree species shape the non-mycorrhizal fungal assemblages in soil and litter and that the divers...
Article
Full-text available
Florestas em solos arenosos são consideradas como hospedeiras de muitos fungos ectomicorrízicos (EM), como demonstrado pelas numerosas coletas feitas por Rolf Singer na região do Rio Negro, Amazonas, no final dos anos 70. Apesar do reconhecimento da importância dos fungos ectomicorrízicos em florestas em solos arenosos, não houve nenhum estudo sist...
Article
Full-text available
1.Resource control over abundance, structure and functional diversity of soil microbial communities is a key determinant of soil processes and related ecosystem functioning. Copiotrophic organisms tend to be found in environments which are rich in nutrients, particularly carbon, in contrast to oligotrophs, which survive in much lower carbon concent...
Article
Full-text available
Plant leaf litter generally decomposes faster as a group of different species than when individual species decompose alone, but underlying mechanisms of these diversity effects remain poorly understood. Because resource C : N : P stoichiometry (i.e. the ratios of these key elements) exhibits strong control on consumers, we supposed that stoichiomet...
Conference Paper
Coastal tropical rainforests of the Amazon grow on some of the oldest and most nutrient impoverished soils on Earth. Phosphorus (P) availability is particulary low, increasing the competition among organisms for this key element. Accordingly, we found that microbial decomposer communities from a tropical forest of French Guiana sequester leaf litte...
Article
Full-text available
Craterellus olivaceoluteus sp. nov. and Craterellus cinereofimbriatus sp. nov. are described as new to science. These fungi were collected from Guyana in association with ectomycorrhizal host trees in the genera Dicymbe (Fabaceae subfam. Caesalpinioideae) and Pakaraimaea (Dipterocarpaceae). Cantharellus guyanensis Mont., originally described from F...
Article
Within tree communities, the differential use of soil N mineral resources, a key factor in ecosystem functioning, may reflect functional complementarity, a major mechanism that could explain species coexistence in tropical rainforests. Eperua falcata and Dicorynia guianensis, two abundant species cooccurring in rainforests of French Guiana, were ch...
Data
Maximum clade credibility tree of Glomeromycota virtual taxa (VT), inferred using Bayesian phylogenetic analysis of small subunit rRNA gene sequences. Posterior probabilities (when >0.5) for nodes are shown. Glomeromycota nomenclature according to Schüßler et al. (2001) including modifications up to 2010, Schüßler and Walker (2010) and Oehl et al....
Article
Full-text available
We aimed to enhance understanding of the molecular diversity of arbuscular mycorrhizal fungi (AMF) by building a new global dataset targeting previously unstudied geographical areas. In total, we sampled 96 plant species from 25 sites that encompassed all continents except Antarctica. AMF in plant roots were detected by sequencing the nuclear SSU r...
Article
Full-text available
Human-caused alterations of the carbon and nutrient cycles are expected to impact tropical ecosystems in the near future. Here we evaluated how a combined change in carbon (C), nitrogen (N) and phosphorus (P) availability affects soil and litter microbial respiration and litter decomposition in an undisturbed Amazonian rainforest in French Guiana....
Data
Mean values of litter mass loss, litter SIR, and soil SIR for each of the six different litter species and each individual fertilization treatment separated into fine and coarse mesh litterbags. (DOC)
Data
Litter SIR as a function of litter mass loss across all litter species and fertilization treatments but separated into coarse (grey circles) and fine (open circles) mesh litterbags. Lines indicated fitted exponential (solid line) or linear (dashed line) regressions for the two fauna treatments separately. (DOC)
Conference Paper
Background/Question/Methods Heterotrophic decomposers contribute critically to ecosystem carbon (C) and nutrient cycling. Decomposer abundance and activity are mainly determined by environmental factors and the quality of plant litter as their major food source. Under near optimal temperature and moisture conditions such as in humid tropical fore...
Article
Full-text available
Tropical forests determine global biogeochemical cycles to a large extent, but control factors for key ecosystem processes such as decomposition remain poorly understood. With a full-factorial C (cellu- lose), N (urea), and P (phosphate) fertilization experiment, we tested the relative importance of C and nutrient limitation on litter decomposition...
Conference Paper
Background/Question/Methods In nutrient poor tropical rainforests, leaf litter decomposition is of key importance for nutrient availability to plants and soil microorganisms. In addition, microbial decomposers are supposed to be sensitive to substrate C to nutrient ratios because they display a narrower C:nutrient ratio than the plant litter they...
Article
Full-text available
The maintenance in the long run of a positive carbon balance under very low irradiance is a prerequisite for survival of tree seedlings below the canopy or in small gaps in a tropical rainforest. To provide a quantitative basis for this assumption, experiments were carried out to determine whether construction cost (CC) and payback time for leaves...
Article
Tree species-rich tropical rainforests are characterized by a highly variable quality of leaf litter input to the soil at small spatial scales. This diverse plant litter is a major source of energy and nutrients for soil microorganisms, particularly in rainforests developed on old and nutrient-impoverished soils. Here we tested the hypothesis that...
Article
Full-text available
Plant litter diversity effects on decomposition rates are frequently reported, but with a strong bias towards temperate ecosystems. Altered decomposition and nutrient recycling with changing litter diversity may be particularly important in tree species-rich tropical rainforests on nutrient-poor soils. Using 28 different mixtures of leaf litter fro...
Conference Paper
Background/Question/Methods Decomposition and associated nutrient cycling is a key process for ecosystem functioning, in particular in tropical rainforests with highly weathered and nutrient-impoverished soils. Previous studies in an Amazonian rainforest of French Guiana showed high variation in leaf litter quality among co-occurring tree species....
Article
Full-text available
• Chlorophyll meters such as the SPAD-502 offer a simple, inexpensive and rapid method to estimate foliar chlorophyll content. However, values provided by SPAD-502 are unitless and require empirical calibrations between SPAD units and extracted chlorophyll values. • Leaves of 13 tree species from the tropical rain forest in French Guiana were samp...
Article
Previous studies in lowland tropical rainforests of French Guiana showed that, among non-N2-fixing trees, two groups of late successional species contrasting in their leaf 15N natural abundance coexist, suggesting two different main ways of nitrogen acquisition. Two abundant late-successional species typically co-occurring in rainforests in French...
Article
Microbial-based indicators, such as C and N contents or microbial functions involved in C and N cycles, are currently used to describe the status of soils in disturbed areas. Microbial functions are more accurate indicators but their measurement for studies at the ecosystem level remains problematical because of the huge spatial variability of thes...
Article
Extracting and purifying a representative fraction of bacteria from soil is necessary for the application of many techniques of microbial ecology. Here the influence of different soil types on the quantitative and qualitative recovery of bacteria by soil grinding and Nycodenz density gradient centrifugation was investigated. Three soils presenting...
Article
Full-text available
Ce travail s'intègre dans des problématiques actuelles cherchant à caractériser l'impact des activités humaines sur les écosystèmes. Le sol, et en particulier, les communautés microbiennes fonctionnelles, abordées simultanément en tant qu'actrices des bio-transformations et en tant que biodescriptrices de l'état fonctionnel du système, ont été l'ob...
Thesis
Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, 97387 Kourou, Guyane (France) Diplôme : Diplôme d'Ingénieur Forestier

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Project (1)
Project
A major challenge for ecologists is to understand and predict the ecological consequences of climate change, land use change and disturbances. To meet this challenge, we need to account not only for environmental change effects on species performances and ranges but also for effects on species interactions. The alterations of species interactions are likely to create cascading effects that can result in non-linear responses, potentially leading to critical and irreversible transitions of ecosystems at short time scales but also over large spatial scales. The assumption that species interactions are only important at small spatial scales has indeed generated considerable debate. Until recently the prevailing idea was that biotic assembly processes (e.g. interspecific competition and trophic interactions) were only important at small spatial scales. Conceptual work and microcosms experiments early challenged this assumption, which has been strengthened by recent studies empirically demonstrating the importance of biotic interactions up to continental scales. It has been argued that determining the direction and magnitude of global change impacts on species interactions remains one of the greatest challenges for forecasting community and ecosystem dynamics. The main objective of the GlobNets project is thus to decipher multi-trophic assemblages at biogeographic scales and to understand their responses to spatial segregation, environmental gradients and/or human activities. To do so, GlobNets builds on new mathematical developments and environmental DNA metabarcoding. We will collect an unprecedented multi-trophic assemblage dataset of soil-plant biodiversity that covers the three super-kingdoms of life (Eukaryota, Bacteria and Archaea) across multiple forest plots along gradients of climate and land-use pressure in 12 distinct forest sites around the globe (tropical, temperate and boreal forests). GlobNets will address the following objectives: I. Develop publicly available multi-scale, multi-trophic and standardized data comprising sampled sites from major forest biomes of the world that contain information on species and functional group co-occurrences from the whole tree of life. In each sampled site, samples are replicated along environmental or disturbance gradients. II. Develop new mathematical and statistical tools for the analyses of multi-trophic community data from eDNA that allow for unbiased within, between and overall community diversity estimates (i.e. a, ß and ? components) and for an approximation of interaction probabilities within and across trophic levels. III. Based on I and II, map and describe the distribution of forest soil and plant diversity across biomes and test for which trophic levels the latitudinal diversity gradient hypothesis holds. IV. Analyse the response of forest soil and plant diversity to large-scale climate and regional-scale environmental and disturbance gradients, detect co-variation between trophic levels as well as between above and belowground compartments V.Based on a suitable sub-set of the dataset, provide a decomposition of diversity into a, ß, and ? components and test long-standing ecological hypotheses related to disturbance and stress gradients across climatic regions, specific abiotic drivers and trophic levels. VI.Based on the methods developed in II, conduct the first global biogeographical description of soil-based co-occurrence networks for a major ecosystem (i.e. forest) including members from the whole tree of life (i.e. Eukaryota, Bacteria and Archaea). VII.Based on a suitable subset of the data (i.e. including those interaction partners that are identified with enough certainty), investigate how strongly network complexity and modularity are influenced by large-scale climatic filters and regional-scale environmental and disturbance filters. Finally, provide a biogeographical description of network robustness based on simulations of cascading species extinctions.