Aude Ernoult

• Professor
• University of Rennes

Understanding the drivers of assemblages of arbuscular mycorrhizal fungi (AMF) is essential to leverage the benefits of AMF for plant growth and health. Arbuscular mycorrhizal fungi are heterogeneously distributed in space even at small scale. We review the role of plant distribution in driving AMF assemblages (the passenger hypothesis), using a tr...

In ever‐changing landscapes, there is increasing evidence that current plant assemblages are shaped by the temporal dynamics of landscape connectivity. So far, attempts to take the temporal dynamics of connectivity into account have only focused on the degree of connectivity at one or several moments in time, but neglected the cumulative effects of...

Bocage landscapes are characterized by a network of hedgerows that delimits arable fields. Such landscapes provide many ecosystem services, including biodiversity conservation, but their effects on weed communities remain largely unknown. Bocage landscapes could affect weed communities through two main processes: plant spillover from hedgerows and...

Landscape structure is one of the main drivers of biodiversity, especially in agricultural landscapes. However, only a few studies explored its effect on the gamma functional diversity of plants. Yet, research questions at this scale are important to better understand and effectively preserve biodiversity. Using a large‐scale sampling design with 3...

While studies have explored how habitat amount drives weed assemblages in agroecosystems, knowledge remains limited of the effects of habitat connectivity. The response-effect trait framework provides insights into the mechanisms underpinning the relationship between landscape structure and the taxonomic diversity and abundance of weed assemblages....

Question Habitat isolation is a major driver of biodiversity because it affects dispersal among local communities, especially for plants. Corridors are supposed to facilitate the movement of organisms and hence their effective dispersal, thereby increasing biodiversity. Hedgerows provide favorable habitats for forest plant establishment, but their...

Hedgerows are semi-natural wooded habitats and an important element in agricultural landscapes across Western and North Western Europe. They reduce erosion, function as carbon sinks and thus provide essential ecosystem services. Moreover, they form a structurally diverse ecosystem for numerous taxa and connect otherwise fragmented forest habitats....

In forest-specialist mammals, forest loss may induce resistance to animal movement and reduce gene flow between populations, and thereby increase genetic erosion and extinction risks for populations. Understanding how landscape features affect gene flow is of critical importance for conservation. Using landscape genetic tools at multiple spatial sc...

ContextLandscape connectivity plays a key role in determining the persistence of species inhabiting fragmented habitat patches. In dynamic landscapes, most studies measure connectivity at multiple time steps, but pay less attention to explicitly quantifying its temporal dynamics to gain insights into its role in biodiversity patterns, thereby enabl...

Landscape structure is a major driver of biodiversity in agricultural landscapes. However, the response of biodiversity can be delayed after landscape changes. This study aimed to determine the effect of current and past landscape structure on plant and bird assemblages. We used a trait-based approach to understand their responses to landscape simp...

One of the major planning tools to respond to urban landscape fragmentation is the development of ecological corridors, that is, interconnected networks of urban green and blue spaces. Least‐cost paths (LCP) appear to be an easy and appropriate resistance‐based modelling method to respond to urban planners’ needs. However, the ecological validation...

How connectivity affects plant assemblages is a central issue in landscape ecology. So far, empirical studies have produced contradictory results, possibly because studies: (1) inaccurately assess connectivity by prioritizing the respective effect of the type of habitat on plant assemblages and (2) omit the range of possible plant responses to conn...

Landscape connectivity promotes dispersal and other types of movement, including foraging activity; consequently, the inclusion of connectivity concept is a priority in conservation and landscape planning in response to fragmentation. Urban planners expect the scientific community to provide them with an easy, but scientifically rigorous, method to...

Context Fragmentation in agricultural landscapes is considered as a major threat to biodiversity. Thus, ecological corridors are deployed at multiple scales to increase connectivity. However, there is limited consensus about their efficiency, especially for plants. Objectives We assimilated existing knowledge to assess whether and how landscape co...

Partie 1. Structuration et fonctionnement écologique des paysages agricoles Chapitre 5

Ce chapitre expose les différentes approches adoptées par les écologues pour étudier et comprendre les interactions entre les caractéristiques des paysages agricoles, la biodiversité et les processus écologiques qui lui sont associés. Il présente dans un premier temps l’approche classiquement centrée sur la fragmentation et l’hétérogénéité paysagèr...

Comme nous l’avons vu au chapitre 4, de nombreuses méthodes sont disponibles pour caractériser les paysages. La modélisation statistique vise ensuite à mettre en relation les caractéristiques des paysages avec une variable-réponse biologique. Il peut s’agir de l’abondance d’un bioagresseur (ravageur des cultures, agent responsable d’une maladie, pl...

One response to biodiversity decline is the definition of ecological networks that extend beyond protected areas and promote connectivity in human-dominated landscapes. In farmland, landscape ecological research has focused more on wooded than open habitat networks. In our study, we assessed the influence of permanent grassland connectivity, descri...

Urban areas are highly fragmented and thereby exert strong constraints on individual dispersal. Despite this, some species manage to persist in urban areas, such as the garden snail, Cornu aspersum, which is common in cityscapes despite its low mobility. Using landscape genetic approaches, we combined study area replication and multi-scale analysis...

Questions How does connectivity affect animal‐dispersed plant assemblages in woodlots of agriculture‐dominated landscapes? Is this effect dependent on zoochorous dispersal modes? Location Long Term Socio‐Ecological Research (LTSER) site of “Zone Atelier Armorique” (ca. 150 km²), Brittany (Western France) Methods We sampled 26 small post‐agricultu...

Context Studying communities using a trait-based approach has contributed to major advances in the understanding of community assembly mechanisms, but research has primarily focused on the effect of local biotic and abiotic processes on plant assemblages. Objectives At the landscape level, we expect that the diversity of trait values (i.e. functio...

Aims Landscape fragmentation has strong negative consequences on biodiversity. In networks of linear elements, connectivity loss results in a decreased length of connected elements and increased potential barriers, directly impacting the ability of plants to disperse. However, species vary in their tolerance to connectivity loss, likely due to diff...

Landscape composition and configuration are considered important factors influencing biodiversity in agricultural landscapes. Evaluating the relative importance of each component is complicated because they are often correlated. Overcoming this problem could lead to a better understanding of the mechanisms that drive biodiversity and help to determ...

ContextThe importance of landscape complexity for biological control is well-known, but its functional roles are poorly understood. Objectives We evaluated the landscape capacity to provide floral resources for beneficial insects and its consequences for biological control in fields. Methods The gut contents of adult hoverflies sampled in 41 cereal...

Dispersal plays a major role in many ecological and evolutionary processes. Facilitating dispersal movements, by promoting ecological connectivity (the degree to which the landscape facilitates or impedes movement among resource patches) is considered as a major conservation issue, notably in urban landscapes (expanding strongly impervious and char...

Movement ecology and landscape ecology are linked through many concepts. As illustration, movement and dispersal are the key processes underlying the concept of landscape connectivity (the degree to which the landscape facilitates or impedes movement among resource patches). Despite the recognition of connectivity as a conservation priority in resp...

Landscape heterogeneity has been shown to be a major factor in the maintenance of biodiversity and associated services in agricultural landscapes. Farmlands are mosaics of fields with various crop types and farming practices. Crop phenology creates asynchrony between fields sown and harvested in different periods (winter vs. spring crops). The pres...

In intensive agricultural landscapes, plant species previously relying on semi-natural habitats may persist as metapopulations within landscape linear elements. Maintenance of populations' connectivity through pollen and seed dispersal is a key factor in species persistence in the face of substantial habitat loss. The goals of this study were to in...

Au sein des paysages agricoles, la mise en place de bandes enherbées (BE) a pour objectif de limiter la contamination des milieux en aval des parcelles cultivées, tels que les cours d’eau. Ces dispositifs végétalisés sont des zones tampons qui interceptent les flux d’engrais et de produits phytosanitaires (pesticides). Au sein de la Zone Atelier Ar...

In agriculture-dominated landscapes, agricultural intensification and associated landscape homogenization have caused large declines in farmland biodiversity. This study was aimed at determining how agricultural landscape composition drives community diversity and composition of farmland birds in the characteristic bocage landscape in Brittany (NW...

Over the last 30 years, ecological networks have been deployed to reduce global biodiversity loss by enhancing landscape connectivity. Bird species dwelling in woodland habitats that are embedded in agriculture-dominated landscapes are expected to be particularly sensitive to the loss of connectivity. This study aimed to determine the role of lands...

Semi-natural habitats are considered as the main source of biodiversity in agricultural landscapes. Most landscape ecology research has focused on the amount (relative surface) and spatial organisation of these habitats. However, these two components of landscape heterogeneity, composition and configuration, are often correlated. Also, landscape st...

The fragmentation of agricultural landscapes has a major impact on biodiversity. In addition to habitat loss, dispersal limitation increasingly appears as a significant driver of biodiversity decline. Landscape linear elements, like ditches, may reduce the negative impacts of fragmentation by enhancing connectivity for many organisms, in addition t...

Landscape heterogeneity is a major driver of biodiversity in agricultural areas and represents an important parameter in conservation strategies. However, most landscape ecology studies measure gamma diversity of a single habitat type, despite the assessment of multiple habitats at a landscape scale being more appropriate. This study aimed to deter...

Background/Question/Methods Since the recognition of the importance of biodiversity for agro-ecosystem functioning and ecosystem services, maintaining biodiversity in agricultural areas has been a major issue. Landscape heterogeneity is a key factor for sustaining and restoring biodiversity. Most studies dealing with landscape effects on biodivers...

Non‐random spatial patterns are a common feature of plant communities. However, the mechanisms leading to their formation remain unknown. The clonal dispersal ability of a species, that is, the average length of spacers between ramets, is commonly acknowledged to influence spatial patterns in clonal plants, although this relationship remains to be...

In the context of rapid and severe biodiversity decline in agroecosystems, the European Union has introduced agri-environmental schemes. However, these schemes require evaluation to estimate their efficiency, for further consolidation and improvement. The establishment of grassy strips along watercourses represents a measure of cross-compliance int...

Under the current context of global change that largely threatens overall biodiversity in increasingly fragmented landscapes, more insights are needed into the drivers of biological connectivity between communities (i.e. the flow of species among a set of local communities responding to landscape structure). This study aims at estimating an indicat...

L’importance de la biodiversité pour le fonctionnement des agrosystèmes et les services écosystémiques font de son maintien dans les paysages agricoles un enjeu majeur. Les études sur l’effet du paysage sur la biodiversité se focalisent généralement sur les habitats semi-naturels et considèrent des phénomènes de complémentation avec les éléments cu...

L’homogénéisation du paysage, associée à l’intensification agricole, a provoqué des pertes importantes de biodiversité. Cette étude vise à déterminer comment les paysages et les pratiques agricoles sont corrélés avec la distribution à grande échelle des oiseaux des milieux agricoles en Bretagne. A partir de l’atlas des oiseaux nicheurs de la région...

Les prairies permanentes sont des habitats subissant une forte fragmentation depuis plus de 60 ans. Cette fragmentation, principalement due à une intensification de l’agriculture, induit une diminution de la diversité biologique de ces milieux. Face à ce constat, il devient essentiel de comprendre quels sont les drivers de la connectivité biologiqu...

Journée de rencontres « Ecologie et écosystèmes : comment ça marche ? »

Agricultural intensification and its associated landscape homogenization have caused a major decline in biodiversity. In Brittany (NW France) the landscape is dominated by agriculture and strongly influenced by intensive farming devoted to dairy cows, pigs and poultry. Widespread crops are rotational grassland, maize and cereal, while vegetable cro...

Understanding the determinants of hedgerow plant diversity in agricultural landscapes remains a difficult task, because the potential drivers affect the complete range of biodiversity components (alpha to gamma diversity). We surveyed herbaceous plant communities (of a height <1.5m) in 84 hedgerows in the Seine river floodplain of France. Two types...

A host may be physically isolated in space and then may correspond to a geographical island, but it may also be separated from its local neighbours by hundreds of millions of years of evolutionary history, and may form in this case an evolutionarily distinct island. We test how this affects the assembly processes of the host's colonizers, this ques...

This landscape study was based on the sampling of 20 replicated landscape sites (1km2 each) that were located within the floodplain of the river Seine. For each site, 13 landscape variables were measured at three dates (1963–1985–2000). The aim of this study was to investigate the overall landscape variability through its different dimensions (spac...

Nous avons étudié l'influence de la composition d'un peuplement sur la variabilité qualitative et l'hétérogénéité spatiale des formes d'humus en comparant un peuplement pur de hêtre et un peuplement mélangé (70 % hêtre - 30 % charme). Les caractéristiques macro-morphologiques des formes d'humus ainsi que la composition spécifique de la litière, l'é...

Changes in landscape pattern under the control of agriculture intensification are consid-ered to be an important driver of biodiversity and often a threat for conservation. The response of species to landscape changes is complex, including possible time lags, and depends on the taxonomic group. The search for surrogate species or surrogate data for...

Despite the widespread need to predict and assess the effects of landscape change on biodiversity, the array of tools available for this purpose is still limited. Species patterns and human activities such as land use respond to the environment on their own suite of scales in space and time so that their interactions are overlapping but complex. It...