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1. Consequences of a decline in pollination function in semi‐natural ecosystems are largely unknown due to variability in pollinator effectiveness, that is, their contribution to pollen deposition alone. While pollination effectiveness has been shown to be related to body size and hairiness of pollinators for some crops, studies encompassing a wide diversity of pollinators interacting with wild plant communities are lacking. 2. Thus, the relationships between pollen load, which is a measurement of pollen transport ability and a proxy of pollinator effectiveness, and morphological traits of pollinators sampled in 16 grasslands in Moselle, France, were investigated. The area, hairiness, and pollen load of each pollinator's face were measured for 658 individuals from 127 bee and fly species interacting with 36 wild plant species. Pollinator dry mass was also measured on 543 individuals from 109 species. 3. Dry body mass and facial area of pollinators were positively linked. This study highlights that bees transported significantly more pollen grains on their face than flies. Furthermore, bees' faces were larger and hairier. We also found that pollinators' facial pollen load increased with facial area and hairiness when we considered all pollinators. However, hairiness is not significant within pollinator group (bees or flies), mirroring a potential phylogenetic signal. 4. Hence, this study shows a wide diversity of pollinator and plant species in which larger and hairier pollinators may transport more pollen grains, at least on their face. However, future studies involving other pollinator body parts are needed to generalise these relationships. [ABSTRACT FROM AUTHOR]

Several components of predator functional diversity have been hypothesized to influence prey suppression through either niche complementarity or mass ratio effects. Nevertheless, most studies have used a functional group approach when assessing the role of these predators in ecosystem functioning. By adopting a trait‐based approach, we evaluated the relative contributions of carabid diversity components in predicting prey suppression. Our results highlight the importance of both taxonomic and functional diversity components of carabids as key drivers of prey suppression. Prey suppression was best predicted by carabid densities, with the dominance of Poecilus cupreus potentially driving the positive effect of community total abundance through the mass ratio effect. Prey suppression increased with increasing the density of large carabids. In addition, carabid eye diameter and antennal length were key functional traits for predicting prey suppression. Furthermore, prey suppression increased with increasing carabid functional richness following the niche complementarity effect. In contrast to functional richness, functional evenness and functional divergence of carabid communities were weakly correlated with prey suppression. By identifying which diversity components of carabid communities contribute the most to increase prey suppression, our results can guide efforts aiming to predict the relationship between diversity of these predators and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Simple Summary: Permanent grasslands are main habitats for many plant species and pollinators. Their destruction as well as their intensification has a major impact on plant and pollinator biodiversity, which has a cascading effect on pollination. However, we lack an understanding of these effects, thereby limiting our ability to predict them. In this review, we synthesised the literature on the mechanisms behind this cascade to provide new insights into the relationship between land-use intensification and pollination. By matching functional traits that mediate the relationship between the two trophic levels, we identified major knowledge gaps about how land-use intensification affects plant–pollinator interactions and how it favours plants with generalised floral traits, which are likely harmful to pollination. Permanent grasslands are suitable habitats for many plant and animal species, among which are pollinating insects that provide a wide range of ecosystem services. A global crisis in pollination ecosystem service has been highlighted in recent decades, partly the result of land-use intensification. At the grassland scale, however, the underlying mechanisms of land-use intensification that affect plant–pollinator interactions and pollination remain understudied. In this review, we first synthesise the literature to provide new insights into the relationships between land-use intensification and pollination by using matching community and interaction traits. We then identify knowledge gaps and summarise how land-use intensification of grassland influences floral traits that may in turn be associated with modifications to pollinator matching traits. Last, we summarise how these modifications may affect pollination function on permanent grasslands. Overall, land-use intensification may lead to a shift in flower colour, a decrease in mean nectar tube depth and a decrease in reward production and pollen quality at the community level. This, in turn, may generate a decrease in pollinator mouthparts length and body size, that may favour pollinators that require a low amount of floral reward. We found no study citing the effect of land-use intensification on volatile organic compounds emitted by flowers despite the importance of these molecules in pollinator community composition. Overall, our review highlighted major knowledge gaps about the effects of land-use intensification on plant–pollinator interactions, and suggests that land-use intensification could favour plants with generalised floral traits that adversely affect pollination. [ABSTRACT FROM AUTHOR]

• We analysed relations between grassland variables and floral functional diversity. • We studied consequences of these relations on plant-pollinator interaction frequency. • Floral functional diversity was negatively related to total soil phosphorus content. • Interaction frequency was positively related to total floral functional diversity. • Interaction frequency was positively related to diversity of nectar sugar production. Semi-natural grasslands are threatened habitats providing many ecosystem services, such as climate regulation or water erosion control. Factors affecting the vegetative trait diversity of their plant communities are well studied, but those affecting their floral diversity are not. Local factors, such as land-use intensification and soil characteristics, can greatly influence floral trait diversity in semi-natural grasslands, which in turn can influence pollination function. We selected 16 semi-natural grasslands in France along a local land-use intensification gradient. Floral functional diversity indices were calculated from measurements of five floral traits known to influence interactions with pollinators: flower area, flowering height, floral reflectance, nectar tube depth and nectar sugar production per floral unit. Using linear mixed models, we found a negative influence of phosphorus soil content, and a positive influence of a composite soil variable including soil texture, organic carbon and total nitrogen soil content, on floral functional diversity. However, local land-use intensification did not influence floral functional diversity. Moreover, our results showed a positive relation between floral functional diversity and plant-pollinator interaction frequency as a proxy of pollination function. More specifically, we found a positive influence of the nectar resource diversity (i.e. the variability in production of nectar sugar by flowers) on plant-pollinator interaction frequency. These results, based on a correlative approach and functional diversity indices as measure of functional complementarity, suggest that the diversity of floral traits may promote niche partitioning of pollinators and pollination function approximated by plant-pollinator interaction frequency, and highlight the main role of nectar in this process. [ABSTRACT FROM AUTHOR]

Background: Grasslands provide a wide range of ecosystem services (ESs). However, there is currently no method for easily diagnosing the level of ESs produced. Our aim was to develop ES indicators based on botanical surveys, which are readily available data and integrative of grassland spatiotemporal variability. Methods: Based on academic knowledge and expertise, we identified several simple vegetation criteria that we aggregated using a multicriteria analysis tool to construct indicators of the level of ESs provided by grasslands. In this study, the indicators were calculated from over 2000 botanical surveys spread over a wide biogeographical gradient. Results: Analyses of correlation between the various indicators show that "forage supply" and "diversity conservation" were not correlated. "Forage availability" and "nitrogen availability for the vegetation" were positively linked together and negatively linked to the robustness of the plant community to extreme events. A temporal approach highlights that the "biodiversity conservation" score decreased from 1970 to 2010 and that "nitrogen availability for the vegetation" was lower in 1970 and 1980 than in 2000 and 2010. Conclusions: These results show that our aggregation method based on a large data set of botanical surveys could be appropriate for studying temporal dynamics of ESs. [ABSTRACT FROM AUTHOR]

Functional trait databases are powerful tools in ecology, though most of them contain large amounts of missing values. The goal of this study was to test the effect of imputation methods on the evaluation of trait values at species level and on the subsequent calculation of functional diversity indices at community level using functional trait databases. Two simple imputation methods (average and median), two methods based on ecological hypotheses, and one multiple imputation method were tested using a large plant trait database, together with the influence of the percentage of missing data and differences between functional traits. At community level, the complete-case approach and three functional diversity indices calculated from grassland plant communities were included. At the species level, one of the methods based on ecological hypothesis was for all traits more accurate than imputation with average or median values, but the multiple imputation method was superior for most of the traits. The method based on functional proximity between species was the best method for traits with an unbalanced distribution, while the method based on the existence of relationships between traits was the best for traits with a balanced distribution. The ranking of the grassland communities for their functional diversity indices was not robust with the complete-case approach, even for low percentages of missing data. With the imputation methods based on ecological hypotheses, functional diversity indices could be computed with a maximum of 30% of missing data, without affecting the ranking between grassland communities. The multiple imputation method performed well, but not better than single imputation based on ecological hypothesis and adapted to the distribution of the trait values for the functional identity and range of the communities. Ecological studies using functional trait databases have to deal with missing data using imputation methods corresponding to their specific needs and making the most out of the information available in the databases. Within this framework, this study indicates the possibilities and limits of single imputation methods based on ecological hypothesis and concludes that they could be useful when studying the ranking of communities for their functional diversity indices. [ABSTRACT FROM AUTHOR]

Soil compaction is known to affect plant growth. However, most of the information regarding the effects of this factor on carbon partitioning has been obtained on young plants while little is known about the evolution of these effects with plant age. The objective of this work was to investigate how soil compaction affects carbon assimilation, photosynthate partitioning and morphology of maize plants during vegetative growth up to tassel initiation. A pressure was applied on moist soil to obtain a bulk density of 1.45 g cm−3 (compacted soil (CS) treatment) while the loose soil (LS) treatment (bulk density of 1.30 g cm−3) was obtained by gentle vibration of soil columns. Plants were grown in a growth chamber for 3–6 weeks and carbon partitioning in the plant–soil system was evaluated using 14C pulse-labelling techniques. Soil compaction greatly hampered root elongation and delayed leaf appearance rate, thereby decreasing plant height, shoot and root dry weights and leaf area. The increase in soil bulk density decreased carbon assimilation rate especially in early growth stages. The main effect of soil compaction on assimilate partitioning occurred on carbon exudation, which increased considerably to the detriment of root carbon. Furthermore, soil microbial biomass greatly increased in CS. Two hypotheses were formulated. The first was that increasing soil resistance to root penetration induced a sink limitation in roots and this increased carbon release into the soil and resulted in a root feedback that regulated carbon assimilation rate. The second hypothesis relies on soil–plant water relations since, due to compaction, the pore size distribution has to be considered. In a compacted soil, the peak of the pore size distribution curve is shifted towards the small pore size. The volume of small pores increases and the unsaturated conductivity decreases substantially, when compared to non-compacted soil. Due to small hydraulic conductivity, the inflow into the roots is well below optimum and the plant closes stomata thus reducing carbon assimilation rate. The effects of soil compaction persisted with plant age although the difference between the two treatments, in terms of percentage, decreased at advanced growth stages, especially in the case of root parameters. [Copyright &y& Elsevier]

• Assessment of the conservation status of grasslands should include evaluation of ecosystem funtioning. • Easy-to-obtain proxies for ecosystem properties can be used in diverse semi-natural grasslands. • Most generic proxies are linked to ecosystem properties through non-linear relationships. • Easy-to-obtain proxies have been found for aboveground plant biomass and quality. • LDMC CWM and litter thickness can be used to approach forage digestibility and mineral content. Despite the recommendations of the 1992 European Habitat Directive regarding the evaluation of the conservation status of ecosystems, information on ecosystem functioning is still poorly integrated in long-term monitoring of European semi-natural grasslands. We investigated how to evaluate several ecosystem properties in relation to services provided by grasslands - plant and litter biomass and chemical composition, soil C and N content – by identifying non-destructive proxies involving little or no additional field sampling effort, or calculated from vegetation species composition. These proxies need to be i) informative, i.e. that can be used to approach one or more ecosystem properties based on linear or non-linear relationship models, and ii) generic, i.e. applicable across a wide range of semi-natural grassland habitats and environmental conditions. Based on a large set of field data collected in a variety of semi-natural grasslands in France, we showed that good proxies for ecosystem properties can be identified when the range of climate or soil moisture conditions was reduced. This suggests that these environmental factors influenced the functional pattern of semi-natural grassland ecosystems. The majority of proxies identified so far, including the community weighted mean of leaf dry matter content (LDMC CWM), the height of the herb layer, and litter thickness, are linked to ecosystem properties through non-linear relationships. They are generic in that they are applicable to several grassland habitat types. The height of the herb layer reflects standing plant biomass relatively well, but different non-linear models have to be used depending on climate and soil moisture conditions. Calculating LDMC CWM from species composition data provides a good approximation of the digestibility and P content of plant biomass. Similarly, litter thickness can be used to approach the digestibility and K content of plant biomass in wet grasslands. No generic proxy was found to approximate litter and soil characteristics across the wide range of grasslands habitats under study. By identifying generic and low-constraint proxies for several ecosystem properties, this work provides guidelines for assessing the functioning of semi-natural grasslands - a key criterion of their conservation status - with limited additional field effort and cost compared to plant community monitoring programs. [ABSTRACT FROM AUTHOR]

The objectives of this comparison of two biophysical models of nitrogen losses were to evaluate first whether results were similar and second whether both were equally practical for use by non-scientist users. Results were obtained with the crop model STICS and the environmental model AGRIFLUX based on nitrogen loss simulations across a small groundwater catchment area (<1 km 2 ) located in the Lorraine region in France. Both models simulate the influences of leaching and cropping systems on nitrogen losses in a relevant manner. The authors conclude that limiting the simulations to areas where soils with a greater risk of leaching cover a significant spatial extent would likely yield acceptable results because those soils have more predictable leaching of nitrogen. In addition, the choice of an environmental model such as AGRIFLUX which requires fewer parameters and input variables seems more user-friendly for agro-environmental assessment. The authors then discuss additional challenges for non-scientists such as lack of parameter optimization, which is essential to accurately assessing nitrogen fluxes and indirectly not to limit the diversity of uses of simulated results. Despite current restrictions, with some improvement, biophysical models could become useful environmental assessment tools for non-scientists. [ABSTRACT FROM AUTHOR]

Managing field margins to promote carabid diversity requires understanding the diverse responses of these insects to vegetation structure within these margins. This diversity in carabid responses could be determined by variation in species functional traits, of which body size is likely to be a key factor. In the present study, the effect of vegetation structure within differently managed field margins on species richness, activity-density and size distribution of carabids was investigated. Experimental margin plots were established in three cereal fields using a replicated block design. Carabids were sampled using pitfall traps in the margin plots, the crop edge, and the crop area of the fields. A decision tree analysis was used to classify structural variables of the vegetation according to their effect on carabids. Both a high number of carabid species and those important for effective pest control were associated with the field margins. Management influenced carabids only in the field margin. Higher plant functional diversity was identified as the primary factor promoting carabid species richness. Their activity-density was negatively correlated to the vegetation heterogeneity and positively to percentage of bare ground. Large species presented high activity-density in homogenous vegetation with high proportion of bare ground, whilst small species preferred high plant functional diversity and heterogeneous vegetation. High activity of medium sized species was associated with high but less heterogeneous vegetation. This diversity in carabid responses to the vegetation structure appears to be related not only to variation in their body size, but also in other life history traits such as diet. [ABSTRACT FROM AUTHOR]

Conservation of pollinator abundance and diversity is an important issue because it contributes to maintaining a diverse community of plant species in agroecosystems. The presence of semi-natural areas favorable to pollination is a key factor for achieving this objective of sustainability. Sowing mixtures of dicotyledonous plants that are rich in pollen and nectar as flower strips along field margins is an efficient solution to attract pollinators and to support their foraging activity on arable land. The enhancement of agroecosystems requires operational methods that make it possible to assess the impact of existing and sown semi-natural areas on pollination. We developed here a new predictive indicator that can be used at the field margin and floral levels, which predicts the pollination value of floral diversity and abundance of field margins on arable land. We based the predictive indicator on decision trees using "if-then" linguistic rules because of the lack of sufficient quantitative knowledge about the relationships between floral traits and pollination. This approach makes it possible to use quantitative and qualitative information. We associated fuzzy subsets to the decision trees and the classes of variables in order to avoid the knife-edge effect of class limits. At the species level, the indicator depends on three criteria: (i) visual attractiveness in terms of flower size, color and UV reflection; (ii) flower accessibility according to the botanical family, the symmetry and the shape of the flower; and (iii) the reward linked to pollen and nectar quantity and quality. An aggregation procedure allows us to obtain a value at the field margin level for each month as a function of the flowering period and pollination activity. Examples of calculations for honeybees, wild bees, bumblebees and hoverflies are shown. The evaluation of the predictive quality yielded significant correlations between pollinator abundance and the indicator value. The level of correlation is satisfying for this type of indicator, which might be further improved with additional data on plant traits. Coupling this indicator with a model that assesses the impact of management on plant diversity and abundance will be a further step to help agronomists who work on the improvement of arable farming management in order to lower its negative impact on pollination. [ABSTRACT FROM AUTHOR]

Determining how multiple predators provide better prey suppression is a key step towards developing conservation biological control strategies. While numerous previous studies have demonstrated that diverse predator assemblages can be more effective in controlling pest populations, others have shown that it is the presence or absence of competitively superior species that is critical to pest biological control (i.e. selection effect)., The present study investigated how increasing ground beetle body size diversity increases prey suppression. A mesocosm experiment was conducted to compare invertebrate prey suppression between nine created ground beetle assemblages. Size diversity of these assemblages was manipulated according to three diversity levels: low, medium, and high diversity., Partitioning of the diversity effects revealed that increasing the ground beetle size diversity had no effect on the strength of prey suppression. The absence of an effect of ground beetle size diversity may be because of the absence of resource partitioning among different-sized ground beetles. The amount and range of prey consumed increased with increasing ground beetle body size. Thus, prey suppression was strongly strengthened by the presence of large ground beetles in the assemblages., The present results suggest that for biological pest control, Agri-managers should emphasise practices that promote the presence of large carabids. This is not only because promoting the presence of large carabids could be at least as effective as conserving a diverse ground beetle community, but also because large ground beetles are more vulnerable to environmental disturbances and to predation than ground beetles of the other size classes. [ABSTRACT FROM AUTHOR]

Research has delivered convincing findings on the effect of biodiversity on ecosystem functioning and humankind. Indeed, ecosystems provide provisioning, regulating, supporting, and cultural services. The global value of annual ecosystem services of grasslands and rangelands is about US$ 232 ha year. Nevertheless, the precise evaluation of biodiversity benefits remains challenging. This issue is due to valuation methods, subjective assumptions, and complexity of drivers of plant community dynamics. Here, we review the primary factors that influence plant diversity of permanent grasslands, and we describe underlying processes. These factors must indeed be identified to focus policies meant to preserve and restore plant diversity and to advise farmers about efficient decision rules. We show that plant dynamics of permanent grasslands cannot be explained simply by agricultural management rules, e.g., grazing, fertilization, and mowing, implemented at the field scale. The configuration of the surrounding landscape, e.g., landscape heterogeneity, habitat fragmentation, and connectivity, acts as a species filter that defines the regional species pool and controls seed flow. The regional species pool often contains higher species richness in a heterogeneous landscape, because of a higher diversity of suitable habitats. This regional pool could be a major species sources for permanent grasslands according to the seed flow. We discuss the need to consider all of these factors to understand plant species composition of permanent grasslands and the necessity to study plant communities using both taxonomic and functional approaches. In order to report this integrative approach, we propose a conceptual model based on three ecological challenges-dispersal, establishment, and persistence-that are considered to act as filters on plant diversity, and a graphical representation of the complexity of such studies due to the interaction effects between plant dispersal abilities, forage productivity, disturbances induced by farming practices, and landscape heterogeneity on plant diversity. Last, we discuss the ability of farmers to manage each factor and the necessity of such study in the improvement of the current agro-environment schemes efficiency for farmland biodiversity restoration or preservation. [ABSTRACT FROM AUTHOR]

Question: Are leaf dry matter content, specific leaf area and leaf life span relevant plant traits to discriminate the fertility gradient in species-rich natural grasslands? In other words, is species ranking conserved when nitrogen availability or growing periods change? Location: Toulouse Research Centre, France; 150 m a.s.l. Methods: Fifteen grasses and nine dicotyledons were sown in pure stands in a random block design with three replicates. Each species was cultivated at two levels of nitrogen supply, limiting and non-limiting for growth, with three replications per nitrogen level. Leaf traits were measured across both levels of nitrogen supply and growing periods over the year. Results: Leaf dry matter content values separated the species into three life-form classes (grasses, rosette forbs and upright forbs, P < 0.001). This was not the case for specific leaf area and leaf life span. The three leaf traits were variable across growing periods and nitrogen levels, but the ranking of species was conserved over N-levels and growth periods. Furthermore leaf dry matter content was always less variable than the other leaf traits. Conclusion: We conclude that leaf thy matter content measured only on grasses could be used as an indicator to describe the N-richness of the habitat where native herbaceous vegetation develops. [ABSTRACT FROM AUTHOR]

Abstract: An agro-ecological indicator INlosses was introduced in order to estimate the risks of air and water pollution through nitrogen management on grasslands. The INlosses score in this study corresponded to the lowest score of four sub-indicators (, , and ) which, respectively, provide information on volatilisation, nitrous and nitric oxide emissions in the air and nitrate leaching in groundwater. The score of each sub-indicator was obtained by comparing nitrogen losses to a threshold which corresponded to the maximal level acceptable for the environment (e.g. 50mg NO3 L-1 for the leaching sub-indicator ). The losses in air of NH3, N2O, NO were calculated by means of emission coefficients. Nitrate leaching was estimated from the residual mineral nitrogen in grassland soil found at the beginning of the drainage period. A validation of the indicator by comparing calculated data with measurements of nitrate leaching by ceramic cups was carried out on grazed and hay grasslands. A discrepancy between observed and calculated data was observed when using data from ceramic cups to validate the indicator. Nevertheless, the indicator gave realistic results and is valid for use in order to indicate the degree of pollution risk in agricultural management. [Copyright &y& Elsevier]

• We compared prediction abilities of three grassland classifications. • Classifications differed in method and prediction ability. • No classification predicted ecological characteristics well. • When alone, only agronomic classification predicted characteristics well. • Combining classifications improved predictions. Permanent grasslands produce highly diverse ecosystem goods and services, which need to be easily assessed by decision makers. Naturalists and agronomists classify grasslands in different ways to predict ecological, agronomic and environmental characteristics of the grasslands. However, few studies have compared the prediction abilities of these different classifications using the same botanical relevés, and none has explored the utility of combining classifications. In this study, we attributed a grassland class from each of three classifications (phytosociological, agronomic and functional) to 250 permanent grasslands in north-eastern France to predict 16 characteristics: nine ecological, three agronomic and four environmental. We used statistical model selection to identify the classification or combination of classifications that best predicted each characteristic. Our results showed great prediction ability of agronomic classification, which created the best models for predicting agronomic (yield) and environmental (management, elevation) characteristics. We also identified a strong prediction ability of combining two or all three classifications to predict seven other grassland characteristics. However, grassland classifications did not predict most of the ecological characteristics well. We can assume that phytosociological classification, despite its mainstream use, predicts grassland characteristics less well than agronomic classification. We recommend combining grassland classifications to improve rapid prediction abilities. This study provides new knowledge useful for developing grassland classifications which meet the needs of agronomists and naturalists. [ABSTRACT FROM AUTHOR]