François Mesléard

Tour du Valat Insitute Arles/ University of Avignon, Institut Méditerranéen de Biodiversité et d'Ecologie

Defining a reference ecosystem for ecological restoration project is an essential step. The reference can correspond to the historical ecosystem, can be defined to solve environmental issues or can correspond to a socioecosystem. For the restoration of the Cassaïre site in the Camargue delta in southern France, the reference ecosystems chosen are :...

Breeding birds in agricultural landscapes have declined considerably since the 1950s and the beginning of agricultural intensification in Europe. Given the increasing pressure on agricultural land, it is necessary to identify conservation measures that consume little productive land. We tested the compensation hypothesis which states that field mar...

Increase in pesticide use and landscape homogenization are two key drivers of the decline in farmland biodiversity. The effects of these two drivers are often complex, interactive and vary among taxonomic groups. Our study tested the hypothesis that pesticide use influences the effect of different components of landscape complexity on different tax...

Understanding the determinants of early invasion resistance is a major challenge for designing plant communities that efficiently repel invaders. Recent evidence highlighted the significant role of priority effects in early community assembly as they affect species composition, structure and functional properties, but the consequences of native com...

Our study tested the hypothesis that pesticide use influences the effect of different components of landscape complexity on different taxonomic groups. We assessed the abundance and diversity of 7 taxa in 118 crop fields in 32 rice paddy landscapes of 1*1 km in the Camargue. For each landscape, we measured the length of different field margins, the...

Extensive horse grazing with hardy breeds is largely used in conservation management for restoring species-rich semi-natural grasslands in Europe. As an example, the Donz`ere-Mondragon Rhˆone river embankments (south-eastern France) where horse grazing with Konik polski suc-ceeded to maintain high species richness in patches of open and short grass...

Le 07 août 2009, la fuite accidentelle d’un oléoduc provoquait une marée noire terrestre sur plus de 5 hectares dans la plaine de la Crau, au cœur d’une réserve naturelle située dans le sud-est de la France. Devant l’ampleur de la pollution générée par les 4 700 m3 de pétrole brut épandu, 72 000 tonnes de sols pollués sont retirées l’année suivant...

Within a local assemblage, ecosystem engineers can have major impacts on population dynamics, community composition and ecosystem functions by transforming or creating new habitats. They act as an ecological filter altering community composition through a set of environmental variables. The impact of ants on their environment has been widely studie...

Dry grasslands of the North‐western Mediterranean Basin are semi‐natural species‐rich ecosystems, composed of many annual species and some structuring perennial species. As these grasslands have been used as rangelands for centuries, human management (grazing; fire regimes) is one of their main ecological and evolutionary drivers, along with the Me...

Grazing by herds of herbivores modifies plant communities in different ways, depending on the herbivore species. Horse grazing is already known to be effective in increasing plant diversity and maintaining herbaceous vegetation, creating different types of patches and thus ensuring spatial heterogeneity. On an artificial embankment at the Donzère-M...

Questions Giving a time advance to restored native plant species has recently been considered as a promising way to improve their persistence and reduce invasion success (i.e. through priority effects). However, little is known about the influence of the elapsed time between seeding and invasion and its interaction with other characteristics such a...

L'écopastoralisme est une pratique de gestion écologique en plein essor, dont les bienfaits pourle maintien ou la restauration des milieux naturels ont été largement démontrés. Mais cette solution alternative de gestion obtient-elle les mêmes résultats sur des milieux fortement anthropisés et artificialisés ? Une étude menée sur les digues artifici...

Although not widely used, ecosystem engineers represent a promising and sustainable tool in nature-based ecosystem management and restoration. In grassland ecosystems, a few invertebrates that engineer soils have been identified as key species regulating soil nutrients and plant communities' diversity and dynamics. Here, we assessed the role of the...

The control of invasive species is a central topic of both applied and theoretical research. Understanding how and which ecological theories can be used to improve invasion resistance of plant communities is essential, to design effective control strategies. The theory of limiting similarity, stating that coexistence between species is more limited...

Consumption by animals remains one of the key points to assess the effectiveness of grazing impacts in woodland for increasing understorey plant diversity. To limit the spread of the brambles and restore understorey plant diversity on an artificial embankment an original system of clearings connected by paths was created by mechanically crushing br...

An innovative microwave-based process to control invasive species in the field is currently under development. We investigated the effect of soil compaction levels under three microwave treatment pairings of power and duration (2kW4 min, 2kW8min and 4kW4 min), on seedling emergence of a diverse seed bank and three major invasive species in Europe (...

Depuis le début du 20ème siècle, la construction de barrages et de digues le long du Rhône a provoqué l’apparition de «nouveaux écosystèmes». C’est notamment le cas de la réserve de Donzère-Mondragon, située le long d’un canal de dérivation du Rhône, créée en 1954 et gérée depuis par l’ONCFS. Deux configurations de digues artificielles sont présent...

Les fourmis, de par leurs actions mécaniques et chimiques sur leur environnement, sont souvent qualifiées d’ingénieures de l’écosystème, notamment au sein des formations végétales herbacées. En effet, la construction de galeries et de dépotoirs occasionne des changements dans la nature organique et minérale du sol qui peuvent notamment modifier les...

Many anthropic activities generate soil disturbances, favoring competitive, fast growing invasive plant species at the expense of natives. Active restoration of invasion-resistant plant communities is increasingly recognized as a relevant strategy to combat invasive plant colonization in disturbed areas, but results are often unsatisfying. Historic...

Few studies document the impacts of conservation management practices such as extensive grazing or mowing on the new ecosystems created by industrial conversions. In southern France, the Rhône channelling led to the construction of dykes to protect the Tricastin industrialized area from floods. Aiming to control plant dynamics for safety reasons an...

Les fourmis sont des ingénieurs des écosystèmes dans les milieux de type « pelouse » Cependant alors que leurs impacts sur la végétation ont été largement étudiés, leurs rôles sur la faune du sol sont encore peu connus Bien que les pelouses possèdent généralement une importante biodiversité depuis la deuxième moitié du 20 e siècle, une perte signif...

Mise en place sur un site artificiel créé par l’homme il y a 65 ans, la Réserve de chasse et de faune sauvage de Donzère-Mondragon possède aujourd’hui une grande richesse faunistique et floristique. Nous avons étudié dans quelle mesure les gestions conservatoires appliquées depuis plusieurs années permettent de conserver cette biodiversité. Les pre...

La plaine de la Crau, située au sud-est de la France, comprend, notamment, un écosystème de type steppique d’environ 11 500 hectares dont cinq hectares ont été dégradés par une fuite d’hydrocarbure en 2009. Suite au transfert de 72 000 tonnes de sol identique provenant d’une carrière à proximité, une régénération de la végétation a été mesurée aprè...

A microwave-based process to control invasive species (seeds and adult stages) in the field prior to plant community restoration is currently under development. We investigated the effect of four microwave treatment pairings of Power × Duration (2kW4min, 4kW2min, 2kW8min, and 4kW4min) on seedling emergence of (1) an abandoned field seed bank used a...

Disease emergence events regularly result from human activities such as agriculture, which frequently brings large populations of genetically uniform hosts into contact with potential pathogens. Although viruses cause nearly 50% of emerging plant diseases, there is little systematic information about virus distribution across agro-ecological interf...

Successful invasive plant eradication is rare, because the methods used target the adult stage, not taking into account the development capacity of a large seedbank. Heating by microwave was considered, because it offers a means to quickly reach the temperature required for loss of seed viability and inhibition of germination. Previous results were...

Extensive grazing applied in the form of low instantaneous pressure over a long period is a widespread management practice in protected areas. However this kind of stocking method does not always achieve the expected results, in particular because it fails to limit colonization by woody plants.This is the case in the relict xero-halophytic grasslan...

Extensive grazing by domestic herbivores is a widespread management practice used since the 80s in many European agro-ecosystems such as semi-natural grasslands to maintain open habitats and to enhance biodiversity. Such grazing systems have principally been tested in cultural ecosystems of high nature value threatened by grazing abandonment. Howev...

Mute Swan Cygnus olor numbers have recently increased in a dramatic fashion in Western Europe and in North America, suggesting there could be potential consequences for the rest of the waterbird community. Breeding Mute Swan pairs may behave territorially towards other waterbirds, taking advantage of their larger size, and hence cause concern regar...

Autrefois très abondante en Camargue, au point d’être considérée comme nuisible par les agriculteurs, la population de lapins de garenne (Oryctolagus cuniculus) est aujourd’hui extrêmement réduite. Ce déclin vertigineux n’est pas sans conséquence !

1.According to the dynamic equilibrium hypothesis (DEH), plant species richness is locally controlled by productivity and disturbance. Given that regional conditions widely affect local environmental variables such as soil nutrient availability, the DEH predictions could be improved by considering how climate influences local controls of species ri...

Temporary ponds, acknowledged for their conservation value, are colonized by the invasive crayfish Procambarus clarkii. We have tested the consequences of this colonization for the ecosystem under two contrasted scenarios: one single individual arrival or three individuals arrival. We recreated the temporary pond ecosystem in 1 m2 tanks to investig...

Plantées dans les années 1950 avec des robiniers faux-acacias pour maintenir les berges; les digues artificielles du Rhône au niveau de la Réserve ONCFS de Donzère-Mondragon (Vaucluse-Drôme), sur la concession de la Compagnie Nationale du Rhône, ont été naturellement colonisées par une flore et une faune diversifiée comprenant des espèces à forte v...

Située à cheval sur les départements de la Drôme et du Vaucluse, entre Valence (70 km au sud) et Avignon (65 km au nord), la Réserve de chasse et de faune sauvage de Donzère-Mondragon est un espace naturel très particulier, car il est en majorité constitué par les digues et berges d’un canal de dérivation du Rhône menant à une usine hydro-électriqu...

Our goal was to disentangle the effects of stress removal and disturbance on plant communities of a Mediterranean rangeland, La Crau (southeastern France). We compared undisturbed reference steppe vegetation with vegetation impacted by changes in land use such as earlier phases of cultivation (dating back 20 years) and/or current water infiltration...

The family Geminiviridae comprises seven genera differentiated by genome organisation, sequence similarity and insect vector. Capulavirus, an eighth genus, has been proposed so as to accommodate two newly discovered highly divergent geminiviruses that presently have no known vector. Alfalfa leaf curl virus, identified here as a third capulavirus is...

The aim of the study is to investigate the relative importance of plant-plant interactions with regard to flooding and drought effect on perennial plant performances in wetlands. Flooding is expected to be the major driver and, accordingly, the importance of drought is hardly if ever taken into account. Focusing on five widespread species, the grow...

For centuries, the dry grassland of the plain of La Crau (south-eastern France) has been subjected to numerous disturbances resulting in the destruction and the fragmentation of this emblematic rangeland ecosystem of the Mediterranean. Today, this ecosystem is facing a new threat from a proliferating native species, the bramble (Rubus ulmifolius Sc...

The genomes of a large number of highly diverse novel circular DNA viruses from a wide range of sources have been characterised in recent years, including circular single-stranded DNA (ssDNA) viruses that share similarities with plant-infecting ssDNA viruses of the family Geminiviridae. Here, we describe six novel circular DNA viral genomes that en...

Juncus acutus and J. maritimus are two colonizers of coastal marsh rangeland with worldwide distribution.We tested the effect of salt, temperature, and photoperiod on the germination capacity of seeds of the two Juncus from the Rhoˆne delta (south of France). We measured the first day of germination, the mean time, speed, and rate of germination on...

The plain of la Crau, located in South Eastern France, is a unique pseudo-steppe ecosystem, characterized by the presence of a Mediterranean climate, stony soil and limestone conglomerate at 40cm depth, and a traditional sheep grazing dating back to 6,000 years. Nevertheless, for many decades, this ecosystem has been subjected to numerous exogenous...

Procambarus clarkii, one of the most invasive aquatic species worldwide, is present in Mediterranean estuarine regions. Water management of these deltas involves massive freshwater inputs, reducing wetland salinity and altering natural flooding periods, two important factors for P. clarkii. The paper examines whether water management affects the di...

La biodiversité est en plein bouleversement et nécessite des connaissances issues de toutes les disciplines scientifiques pour aider à sa conservation.

1.Dry matter digestibility is a critical component of herbage nutritive value, a major service delivered by grasslands. The aim of the present study is to test whether the dominance hypothesis applies to assess the impacts of environmental gradients and management regimes on this component of herbage nutritive value in permanent grasslands.2.At the...

QuestionCan plant material transfer combined with topsoil removal be an efficient method of restoring Mediterranean meso-xeric grassland plant communities? Does increasing topsoil removal depth increase the success of plant material transfer establishment?LocationThe Camargue, Rhône delta, France.MethodsA small-scale restoration experiment involvin...

En 1952, la CNR a mis en service l’aménagement hydro-électrique de Donzère -Mondragon. Un canal de dérivation est créé pour alimenter une centrale/écluse « André Blondel » sur le Rhône. Des millions de m3 de déblais ont été stockés sur les berges et plantés avec du robinier. Aujourd’hui, ces digues présentent une importante richesse biologique (plu...

Agri-environment schemes (AES) favouring the maintenance of hedges were implemented in the Camargue (southern France) as it has previously been proven to reduce the risk of damage caused by Greater Flamingo incursions into rice fields. Given the persistent incursions, we estimated the economic cost of damage from 2007 to 2009, the uptake rate of he...

Depuis des siècles, la pseudo-steppe de la Crau (sud-est de la France) est soumise à de nombreuses perturbations entrainant destruction et fragmentation de cet écosystème unique au monde. Outre une diminution de la richesse spécifique et une banalisation de la végétation, la communauté végétale est menacée par Rubus ulmifolius Schott qui colonise l...

Espaces naturels n° 47 juillet 2014 37 forum professionnel i études recherches L'absence d'une banque de graines viables et les faibles capacités de dissémination de nombreuses espèces représentent un frein majeur aux efforts de restauration d'habitats naturels. Pour pallier ces obstacles, parmi d'autres techniques, le transfert de sol est de plus...

Mediterranean temporary wetlands have considerably declined in recent decades. Today, opportunities arise for the restoration of these wetlands due to land-use changes, such as the abandonment of cultivation. One critical question is whether communities, such as those observed in natural temporary wetlands, can develop alone or if active restoratio...

This is essential to understand habitat selection by wildlife to manage habitats and populations. Studying the annual use of aquatic habitats provides information on how to manage wetlands for waterfowl, and to predict possible detrimental effects associated with extended usage by these birds. This is particularly important for species like the mut...

The non-indigenous red swamp crayfish (Procambarus clarkii) has been shown to be a threat for amphibian conservation. Many amphibian species breed in temporary ponds to diminish predation risk as such ecosystems are free of large predators. However P. clarkii, occurring as an invasive species in the Camargue delta, can readily disperse on the groun...

In order to define the flooding tolerance capacity of Limonium girardianum according to growth development stage, we submerged 200 seedlings and 200 four-month-old juveniles in fresh water. During the eleven weeks of the experiment, we recorded the survival, growth and dry biomass of both seedlings and juveniles. Every week, we removed a group of t...

Flamingo forays in the Camargue rice fields only affect a small percentage of the surface area ; however, the damage incurred in the individual fields can be important and may even require the entire area to be replanted. Previous research has demonstrated hedges around rice fields could reduce the attractiveness of the fields for flamingos. In con...

The sea lavender Limonium girardianum (Guss.) Fourr. is endemic to the Mediterranean salt marshes of the French and Spanish coasts. Most of the salt marshes where L. girardianum occurs are exposed to human disturbance, in particular due to industrial expansion. To determine the ecological conditions favorable to the development of L. girardianum, w...