Résumé
We review empirical studies on how bioinvasions alter food webs and how a food-web perspective may change their prediction and management. Predation is found to underlie the most spectacular damage in invaded systems, sometimes cascading down to primary producers. Indirect trophic effects (exploitative and apparent competition) also affect native species, but rarely provoke extinctions, while invaders often have positive bottom-up effects on higher trophic levels. As a result of these trophic interactions, and of nontrophic ones such as mutualisms or ecosystem engineering, invasions can profoundly modify the structure of the entire food web. While few studies have been undertaken at this scale, those that have highlight how network properties such as species richness, phenotypic diversity, and functional diversity, limit the likelihood and impacts of invasions by saturating niche space. Vulnerable communities have unsaturated niche space mainly because of evolutionary history in isolation (islands), dispersal limitation, or anthropogenic disturbance. Evolution also modulates the insertion of invaders into a food web. Exotics and natives are evolutionarily new to one another, and invasion tends to retain alien species that happen to have advantage over residents in trophic interactions. Resident species, therefore, often rapidly evolve traits to better tolerate or exploit invaders—a process that may eventually restore more balanced food webs and prevent extinctions. We discuss how network-based principles might guide management policies to better live with invaders, rather than to undertake the daunting (and often illusory) task of eradicating them one by one.
Auteurs, date et publication :
Auteurs P. David , E. Thébault , O. Anneville , P.-F. Duyck , E. Chapuis , N. Loeuille
Publication : Advances in Ecological Research
Date : 2025
Volume : 56
Pages : 1-60
Catégorie(s)
#INRAE #OLARésumé
Bacteria and fungi naturally coexist in various environments including forest ecosystems. While the role of saprotrophic basidiomycetes in wood decomposition is well established, the influence of these fungi on the functional diversity of the wood-associated bacterial communities has received much less attention. Based on a microcosm experiment, we tested the hypothesis that both the presence of the white-rot fungus Phanerochaete chrysosporium and the wood, as a growth substrate, impacted the functional diversity of these bacterial communities. Microcosms containing sterile sawdust were inoculated with a microbial inoculum extracted from a forest soil, in presence or in absence of P. chrysosporium and subsequently, three enrichment steps were performed. First, bacterial strains were isolated from different microcosms previously analyzed by 16S rRNA gene-based pyrosequencing. Strains isolated from P. chrysosporium mycosphere showed less antagonism against this fungus compared to the strains isolated from the initial forest soil inoculum, suggesting a selection by the fungus of less inhibitory bacterial communities. Moreover, the presence of the fungus in wood resulted in a selection of cellulolytic and xylanolytic bacterial strains, highlighting the role of mycospheric bacteria in wood decomposition. Additionally, the proportion of siderophore-producing bacteria increased along the enrichment steps, suggesting an important role of bacteria in iron mobilization in decaying-wood. Finally, taxonomic identification of 311 bacterial isolates revealed, at the family level, strong similarities with the high-throughput sequencing data as well as with other studies in terms of taxonomic composition of the wood-associated bacterial community, highlighting that the isolated strains are representative of the wood-associated bacterial communities.
Auteurs, date et publication :
Auteurs Vincent Hervé , Elodie Ketter , Jean-Claude Pierrat , Eric Gelhaye , Pascale Frey-Klett
Publication : Plos One
Date : 2025
Pages : 17
Catégorie(s)
#FORET Montiers #INRAEAuteurs, date et publication :
Auteurs Laure Vieublé Gonod , Achouak El Arfaoui , Pierre Benoit
Publication : Soil Biology and Biochemistry
Date : 2025
Volume : 95
Pages : 180-188
Catégorie(s)
#INRAE #PRO #PRO QualiAgroAuteurs, date et publication :
Auteurs Anthony Bouétard , Anne-Laure Besnard , Danièle Vassaux , Laurent Lagadic , Marie-Agnès Coutellec
Publication : Aquatic Toxicology
Date : 2013
Volume : 126
Pages : 256-265
Catégorie(s)
#INRAE #PEARLRésumé
Due to the importance of young-of-the-year (YOY) perch in the peri-alpine regions where they are consumed, the microcystin (MC) contamination of YOY perch was analysed both in field (Lake Bourget, France) and experimentally using force-feeding protocols with pure MCs. In-situ, schools of YOY perch present in the epilimnion of the lake were never found in direct contact with the P. rubescens blooms that were present in the metalimnion. However, MCs were detected in the muscles and liver of the fish and were thus assumed to reach YOY perch through dietary routes, particularly via the consumption of MC-containing Daphnia. Force-feeding experiment demonstrates the existence of MC detoxification/ excretion processes and suggests that in situ, YOY perch could partly detoxify and excrete ingested MCs, thereby limiting the potential negative effects on perch populations under bloom conditions. However, because of chronic exposure these processes could not allow for the complete elimination of MCs. In both experimental and in situ studies, no histological change was observed in YOY perch, indicating that MC concentrations that occurred in Lake Bourget in 2009 were too low to cause histological damage prone to induce mortality. However, Deoxyribonucleic acid (DNA) damages were observed for both the high and low experimental MC doses, suggesting that similar effects could occur in situ and potentially result in perch population disturbance during cyanobacterial blooms. Our results indicate the presence of MCs in wild perch, the consumption of this species coming from Lake Bourget is not contested but more analyses are needed to quantify the risk.
Auteurs, date et publication :
Auteurs Benoît Sotton , Jean Guillard , Sylvie Bony , Alain Devaux , Isabelle Domaizon , Nicolas Givaudan , François Crespeau , Hélène Huet , Orlane Anneville , Sandra Maria Feliciano de Oliveira Azevedo
Publication : Plos One
Date : 2012
Volume : 7
Issue : 12
Pages : e52243
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs P. Cambier , V. Pot , V. Mercier , A. Michaud , P. Benoit , A. Revallier , S. Houot
Publication : Science of The Total Environment
Date : 2025
Volume : 499
Pages : 560–573
Catégorie(s)
#INRAE #PRO #PRO QualiAgroRésumé
In forest ecosystems, fungi are the key actors in wood decay. They have the capability to degrade lignified substrates and the woody biomass of coniferous forests, with brown rot fungi being common colonizers. Brown rots are typically involved in the earliest phase of lignocellulose breakdown, which therefore influences colo nization by other microorganisms. However, few studies have focused on the impact of introducing decayed wood into forest environments to gauge successional colonization by natural bacterial and fungal communities following partial decay. This study aimed to address this issue by investigating the bacterial and fungal colo nization of Norway spruce (Picea abies) wood, after intermediate and advanced laboratory-based, pre-decay, by the brown rot fungus Gloeophyllum trabeum. Using Illumina metabarcoding, the in situ colonization of the wood blocks was monitored 70 days after the blocks were placed on the forest floor and covered with litter. We observed significant changes in the bacterial and fungal communities associated with the pre-decayed stage. Further, the wood substrate condition acted as a gatekeeper by reducing richness for both microbial communities and diversity of fungal communities. Our data also suggest that the growth of some fungal and bacterial species was driven by similar environmental conditions.
Auteurs, date et publication :
Auteurs Nicolas Valette , Arnaud Legout , Barry Goodell , Gry Alfredsen , Lucas Auer , Eric Gelhaye , Delphine Derrien
Publication : Fungal Ecology
Date : 2025
Volume : 61
Pages : 101188
Catégorie(s)
#ANR-Citation #FORET Breuil #INRAERésumé
The pea root rot complex is a major concern for green pea production worldwide. This study aimed at characterizing its composition and dynamics throughout a cropping season in northern France. To this end, fungi and oomycetes were isolated from green pea plant roots with symptoms sampled at the flowering stage in 22 fields in 2017, and at the pea emergence, elongation and flowering stages in two fields in 2018. Out of 646 isolates collected, 317 were identified using molecular markers. Fusarium oxysporum, F. solani and F. redolens were highly predominant. Pathogenicity tests separated the isolates into four aggressiveness groups. F. solani isolates were the most aggressive. Phylogenetic analysis of their TEF1 sequences showed that they mainly belonged to the F. pisi lineage, and that F. oxysporum isolates were genetically close to isolates from the UK that did not belong to the forma specialis pisi. In addition, several Clonostachys rhizophaga isolates are reported for the first time to cause pea root rot. The oomycetes were rarely found and were represented by a few Pythium spp. isolates. Lastly, this study shows that the fungal and oomycete communities associated with pea root rot change during the cropping season. The level of dissimilarity of the root-rot-associated communities decreased throughout the cropping season towards a more similar composition at the flowering stage, dominated by F. solani, F. oxysporum and F. redolens. The proportion of nonpathogenic to weakly pathogenic isolates decreased progressively during the growing season in favour of moderately to highly pathogenic isolates.
Auteurs, date et publication :
Auteurs Simon Gibert , Veronique Edel-Hermann , Elodie Gautheron , Nadine Gautheron , Eric Bernaud , Jean-Marie Sol , Gery Capelle , Rachel Galland , Arnaud Bardon-Debats , Claudine Lambert , Christian Steinberg
Publication : PLANT PATHOLOGY
Date : 2022
Volume : 71
Issue : 7
Pages : 1550-1569
Catégorie(s)
#ANR-Citation #Genosol #INRAERésumé
For spatial crop and agro-systems modelling, there is often a discrepancy between the scale of measured driving data and the target resolution. Spatial data aggregation is often necessary, which can introduce additional uncertainty into the simulation results. Previous studies have shown that climate data aggregation has little effect on simulation of phenological stages, but effects on net primary production (NPP) might still be expected through changing the length of the growing season and the period of grain filling. This study investigates the impact of spatial climate data aggregation on NPP simulation results, applying eleven different models for the same study region (∼34,000km2), situated in Western Germany. To isolate effects of climate, soil data and management were assumed to be constant over the entire study area and over the entire study period of 29 years. Two crops, winter wheat and silage maize, were tested as monocultures. Compared to the impact of climate data aggregation on yield, the effect on NPP is in a similar range, but is slightly lower, with only small impacts on averages over the entire simulation period and study region. Maximum differences between the five scales in the range of 1–100km grid cells show changes of 0.4–7.8% and 0.0–4.8% for wheat and maize, respectively, whereas the simulated potential NPP averages of the models show a wide range (1.9–4.2gCm−2d−1 and 2.7–6.1gCm−2d−1 for wheat and maize, respectively). The impact of the spatial aggregation was also tested for shorter time periods, to see if impacts over shorter periods attenuate over longer periods. The results show larger impacts for single years (up to 9.4% for wheat and up to 13.6% for maize). An analysis of extreme weather conditions shows an aggregation effect in vulnerability up to 12.8% and 15.5% between the different resolutions for wheat and maize, respectively. Simulations of NPP averages over larger areas (e.g. regional scale) and longer time periods (several years) are relatively insensitive to climate data aggregation. However, the scale of climate data is more relevant for impacts on annual averages of NPP or if the period is strongly affected or dominated by drought stress. There should be an awareness of the greater uncertainty for the NPP values in these situations if data are not available at high resolution. On the other hand, the results suggest that there is no need to simulate at high resolution for long term regional NPP averages based on the simplified assumptions (soil and management constant in time and space) used in this study.
Auteurs, date et publication :
Auteurs Matthias Kuhnert , Jagadeesh Yeluripati , Pete Smith , Holger Hoffmann , Marcel van Oijen , Julie Constantin , Elsa Coucheney , Rene Dechow , Henrik Eckersten , Thomas Gaiser , Balász Grosz , Edwin Haas , Kurt-Christian Kersebaum , Ralf Kiese , Steffen Klatt , Elisabet Lewan , Claas Nendel , Helene Raynal , Carmen Sosa , Xenia Specka
Publication : European Journal of Agronomy
Date : 2017
Volume : 88
Pages : 41-52
Catégorie(s)
#INRAE #RecordRésumé
Trees play a crucial role in nutrient cycling and ecosystem fertility, notably through rhizosphere processes. The aim of this study was to compare soil physicochemical properties between bulk soil and rhizosphere of several tree species, and to compare rhizosphere properties between fertilized and non-fertilized conditions. The soil sampling was performed in Breuil-Chenue forest (North-East of France) in seven stands: native forest (old beech (Fagus sylvatica L.) and oak (Quercus sessiliflora Smith) coppice with standards; CwS), beech, oak (Quercus petraea [Matt.] Liebl.), Douglas-fir and fertilised Douglas-fir, Norway spruce (Picea abies Karst.) and fertilised Norway spruce. Systematic soil sampling was performed at 0–3, 3–10, and 10–23 cm in 20 calibrated pits. The rhizosphere of the different species was generally enriched in C, N, Ca, Mg, and K. Interestingly, the same positive effect was observed in the fertilised plots. The rhizosphere effect varied between tree species for C, “base” cations, pHwater and cation exchange capacity. This study reveals that interactions between roots, microorganisms and soil can enrich the pool of nutrients in the rhizosphere compared to bulk soil whatever the soil fertility conditions, and that the magnitude of the rhizosphere effect depends on tree species.
Auteurs, date et publication :
Auteurs Christophe Calvaruso , Victor N’Dira , Marie-Pierre Turpault
Publication : Plant and Soil
Date : 2011
Volume : 342
Issue : 1
Pages : 469-480