L’éléphant africain offert à Henri IV par des marins de Dieppe (1591)

International audienceThe arrival in Dieppe of an elephant offered as a gift to King Henry IV is the subject, in 1893, of a short note edited by Léopold Delisle. The discovery of new sources invites a reinterpretation of this extraordinary event since it is probably the first African elephant introduced in Europe by the Atlantic route since Ancient history.The shipping of a young 5-year-old pachyderm during several weeks requires particularly elaborate logistics : the carriers must prevent the animal from getting scared or ill, they must also insure that it is getting the water and food necessary for its growth and maintenance. The resort to an experienced African healer is unavoidable. The transportation of the elephant from Cape Verde is a remarkable achievement, at the same time technical, commercial and most assuredly diplomatic, thus revealing the great knowledge that the sailors of Dieppe had of the African coasts.Le débarquement à Dieppe d’un éléphant offert en cadeau au roi Henri IV a faitl’objet, en 1893, d’une courte note publiée par Léopold Delisle. La découverte denouvelles sources invite à une relecture de cet événement extraordinaire puisqu’ils’agit sans doute du premier éléphant africain introduit en Europe depuis l’Antiquitépar la voie atlantique. Le transport d’un jeune pachyderme âgé d’environ 5 ans sur unnavire durant plusieurs semaines nécessite une logistique particulièrement élaborée :les transporteurs doivent éviter que l’animal ne prenne peur ou qu’il ne tombe malade,il leur faut également prévoir l’eau et la nourriture nécessaires à sa croissance et à sonentretien. Le recours à un « soigneur » africain expérimenté semble incontournable.Le transport d’un éléphant depuis le Cap-Vert constitue un véritable exploit, à lafois technique, commercial et probablement diplomatique, qui révèle la très grandeconnaissance que les marins de Dieppe avaient des côtes africaines

Taxonomic and functional facets of the resilience to management of mown subalpine grasslands

International audienceQuestions: Sustaining ecosystem services for society in the face of global change is a major challenge. Resilience, an ecosystem's ability to absorb disturbance and return to its initial functioning, is critical for this. We assessed the resilience of mown subalpine grasslands following restoration management. Using a novel multi-indicator approach, we asked how different taxonomic and functional facets of biodiversity influence resilience mechanisms. We demonstrated this approach for a case study in subalpine grasslands, asking: how resilient are grasslands dominated by Patzkea paniculata and their agronomic services to changing mowing regimes? Location: Villar d'Arene, Hautes-Alpes, Provence-Alpes-Cote d'Azur, France. Boundary area of Ecrins National Park. Methods: A manipulative experiment tested the reciprocal effects of mowing cessation and mowing resumption for 10 years. We analysed floristic composition data following four steps. First, we used the Community Structure Integrity Index (CSII; Jaunatre et al., ) to obtain qualitative and quantitative summaries of taxonomic responses. The second step focused on taxonomic biodiversity using species richness, Simpson and Pielou indices, and responsive species identified in the first step. Third, we analysed functional diversity responses using functional groups and community weighted mean (CWM) of vegetative plant traits. Finally, we quantified ecosystem services impacts by estimating fodder quantity and quality using trait-based models. Results: The mowing manipulation demonstrated the high resilience of P. paniculata grasslands and revealed reversibility of transitions between mown and unmown states. By reducing the abundance of P. paniculata, the resumption of mowing restored forage quality. Supported by a complementary case study on post-disturbance re-sowing in hay meadows, this study demonstrates the resilience of mown subalpine grasslands to management change and explores underlying belowground mechanisms of vegetative regeneration and belowground reserves. Conclusion: Our novel multi-indicator approach provides multifaceted mechanistic understanding necessary to anticipate impacts of socio-ecological changes and to maintain the multiple benefits of mountain grasslands. Addressing the different facets of biodiversity from abundance data that are systematically collected in impact or monitoring assessment, this approach provides a common framework, widely applicable to different types of restoration or management interventions, across regions and biota

Designing sampling protocols for plant-pollinator interactions - timing, meteorology, flowering variations and failed captures matter

International audiencePlant-pollinator interactions are key components of ecosystem functioning and are therefore increasingly studied. Of all the approaches used to estimate these interactions, the capture of pollinators along transects is a widely used and recognized method. However, specific choices of sampling design can strongly influence observations of insect visits and bias ecological interpretations. Yet, there is no agreement on the best transect design. Sampling intensity (number and length of transects) is an important element of these choices, but not the only one. Here we investigate the influence of three other facets of protocol choices that commonly arise when designing pollination transects: (i) the influence of sampling conditions that may interact with ecological variables of interest or bias observations, (ii) the measurement of floral availability frequency, and (iii) the management of insects observed but not captured. We quantified the importance of these three protocol choices using a large dataset of 720 plantpollinator transects in protected wet meadows in France. Our results demonstrate the need to (i) cover a wide range of temporal and meteorological conditions for each site, and (ii) repeat the assessment of plot attractiveness for pollinators (a major covariate, usually simply derived from one-off vegetation surveys). In addition, we show that (iii) for analyses of visitation density among insect groups, failed insect captures should not be discarded but incorporated into the analyses. Overall, this research identifies three key choices in transect design and highlights their influence in our understanding of plant-pollinator interactions

Lags in phenological acclimation of mountain grasslands after recent warming

International audience1. In the current biodiversity crisis, one of the crucial questions is how quickly plant communities can acclimate to climate warming and longer growing seasons to buffer the impairment of community functioning. Answering this question is pivotal especially for mountain grasslands that experience harsh conditions but provide essential ecosystem services to people

Lags in phenological acclimation of mountain grasslands after recent warming

1. In the current biodiversity crisis, one of the crucial questions is how quickly plant communities can acclimate to climate warming and longer growing seasons to buffer the impairment of community functioning. Answering this question is pivotal especially for mountain grasslands that experience harsh conditions but provide important ecosystem services to people. 2. We conducted a reciprocal transplant experiment along an elevation gradient (1920 m vs. 2450 m) in the French Alps to test the ability of plant species and communities to acclimate to warming and cooling. For three years, we measured weekly the timing of phenological events (e.g. start of flowering or greening) and the length of phenological stages linked to demographic performance (e.g. lengths of flowering or greening periods). 3. We found that warming (and cooling) changed the timing of phenological events strongly enough to result in complete acclimation for graminoids, for communities in early and mid-season, but not at all for forbs. For example, warming resulted in later greening of communities and delayed all phenophases of graminoids. Lengths of phenological stages did not respond strongly enough to climate change to acclimate completely, except for graminoids. For example, warming led to an acclimation lag in the community's yearly productivity and had a strong negative impact on flowering of forbs. Overall, when there was an acclimation failure, responses to cooling were mostly symmetric and confirmed slow acclimation in mountain grasslands. 4. Synthesis. Our study highlights that phenological plasticity cannot prevent impairment of community functioning under climate warming in the short-term. The failures to acclimate after three years of warming signals that species and communities underperform and are probably at high risk of being replaced by locally better-adapted plants.dataFocals_030621.RData or dataFocals_030621.csv Plot: Treatment groups LC: SubalpineControl LT: AlpineWarmed GC: AlpineControl GT: SubalpineCooled Repetition: Number of plot repetitions Observation_Date: Species: Focal species names Phenophase: Phenological phases as described in the main manuscript Number_of_individuals: Number of individuals present in the phenophase. For details, please refer to the main manuscript. dataNDVI_030621.RData or dataNDVI_030621.csv Plot: Treatment groups LC: SubalpineControl LT: AlpineWarmed GC: AlpineControl GT: SubalpineCooled Subplot: Coding for 1mx1m subplots X: Only for Controls A,B,C,D: Only for Treatments Plot_Repetition: Number of 4mx4m plot repetitions Measurement_Repetition: 3 times measurement repetitions Measurement_Date: Measurement_Sm: Gap-filled NDVI measurements. For the methodology, please refer to the main manuscript. Funding provided by: Agence Nationale de la RechercheCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001665Award Number: TransAlp ANR‐20‐CE02‐0021For the dataset collection and the processing, please refer to the methods section of the manuscript

The contrasted impacts of grasshoppers on soil microbial activities in function of primary production and herbivore diet

International audienceHerbivory can have contrasted impacts on soil microbes and nutrient cycling, which has stimulatedthe development of conceptual frameworks exploring the links between below- and abovegroundprocesses. The “productivity model” predicts that herbivores stimulate microbial activities and acceleratenutrient mineralization in productive ecosystems, while they have an opposite effect in lessproductive ecosystems. In parallel, the “diet model” predicts that herbivores feeding on conservativeplants accelerate nutrient cycling while those feeding on exploitative plants decelerate nutrientcycling, due to changes in litter inputs. Since these two frameworks can lead to conflicting predictionsin some cases, experimental evidence combining herbivore diet and plant productivity is required.During two consecutive years,we conducted an experiment controlling the presence of threegrasshopper species consuming either grasses, forbs or both in twelve natural and managed alpinegrasslands with contrasted productivities. In order to assess the effects of herbivory on soil microbes,we measured their extracellular enzymatic activities, biomass and potential nitrogen mineralization(PNM). Soil and vegetation were also characterized to test how much they modulated the effectsof herbivory on microbes. Contrary to the predictions of the diet model, the effects of herbivory onmicrobial characteristics did not depend on the herbivores diet, but were influenced by primary production,though in a way that differed from the productivity model. The most productive sites wereconstituted by exploitative plant species which depleted N resources in the soil, and by microbesproducing relatively few extracellular enzymes, leading to a lower PNM. Herbivory increased microbialbiomass and decreased the production of extracellular enzymes in those sites, possibly throughthe stimulation of root exudates produced by exploitative species. The least productive sites werecharacterized by conservative plants, high soil C content, and by microbes having a resource acquisitionstrategy (more extracellular enzymes, higher PNM). Herbivory decreased microbial biomassand increased the production of extracellular enzymes in those sites. This pattern can be explainedby the loss of carbon associated with insect respiration, which increases the resource requirementsof microbes and by a lower production of root exudates by conservative species. Therefore, the effectsof two years of herbivory on soil microbes were at odds with the productivity model, whichfocuses instead on longer term effects corresponding to herbivory-induced changes in plant speciescomposition. This highlights the multidimensional feature of the impacts of herbivory on ecosystemfunctioning, both in space and time

The contrasted impacts of grasshoppers on soil microbial activities in function of primary production and herbivore diet

International audienceHerbivory can have contrasted impacts on soil microbes and nutrient cycling, which has stimulatedthe development of conceptual frameworks exploring the links between below- and abovegroundprocesses. The “productivity model” predicts that herbivores stimulate microbial activities and acceleratenutrient mineralization in productive ecosystems, while they have an opposite effect in lessproductive ecosystems. In parallel, the “diet model” predicts that herbivores feeding on conservativeplants accelerate nutrient cycling while those feeding on exploitative plants decelerate nutrientcycling, due to changes in litter inputs. Since these two frameworks can lead to conflicting predictionsin some cases, experimental evidence combining herbivore diet and plant productivity is required.During two consecutive years,we conducted an experiment controlling the presence of threegrasshopper species consuming either grasses, forbs or both in twelve natural and managed alpinegrasslands with contrasted productivities. In order to assess the effects of herbivory on soil microbes,we measured their extracellular enzymatic activities, biomass and potential nitrogen mineralization(PNM). Soil and vegetation were also characterized to test how much they modulated the effectsof herbivory on microbes. Contrary to the predictions of the diet model, the effects of herbivory onmicrobial characteristics did not depend on the herbivores diet, but were influenced by primary production,though in a way that differed from the productivity model. The most productive sites wereconstituted by exploitative plant species which depleted N resources in the soil, and by microbesproducing relatively few extracellular enzymes, leading to a lower PNM. Herbivory increased microbialbiomass and decreased the production of extracellular enzymes in those sites, possibly throughthe stimulation of root exudates produced by exploitative species. The least productive sites werecharacterized by conservative plants, high soil C content, and by microbes having a resource acquisitionstrategy (more extracellular enzymes, higher PNM). Herbivory decreased microbial biomassand increased the production of extracellular enzymes in those sites. This pattern can be explainedby the loss of carbon associated with insect respiration, which increases the resource requirementsof microbes and by a lower production of root exudates by conservative species. Therefore, the effectsof two years of herbivory on soil microbes were at odds with the productivity model, whichfocuses instead on longer term effects corresponding to herbivory-induced changes in plant speciescomposition. This highlights the multidimensional feature of the impacts of herbivory on ecosystemfunctioning, both in space and time

A spatially explicit trait‐based approach uncovers changes in assembly processes under warming

The re-assembly of plant communities during climate warming depends on several concurrent processes. Here, we present a novel framework that integrates spatially explicit sampling, plant trait information and a warming experiment to quantify shifts in these assembly processes. By accounting for spatial distance between individuals, our framework allows separation of potential signals of environmental filtering from those of different types of competition. When applied to an elevational transplant experiment in the French Alps, we found common signals of environmental filtering and competition in all communities. Signals of environmental filtering were generally stronger in alpine than in subalpine control communities, and warming reduced this filter. Competition signals depended on treatments and traits: Symmetrical competition was dominant in control and warmed alpine communities, while hierarchical competition was present in subalpine communities. Our study highlights how distance-dependent frameworks can contribute to a better understanding of transient re-assembly dynamics during environmental change