Assessing the drivers of grassland ground-dwelling arthropod community composition: Integrating landscape-scale farming intensity and local environmental conditions.

Grasslands are essential habitats for preserving arthropod communities in agricultural landscapes. The environmental state of grassland, their farming practices, and land cover heterogeneity in landscape around grassland are three factors that influence ground-dwelling grassland arthropod communities. However, the impact of the intensity of farming practices at the landscape scale has not yet been fully explored. In this study, (i) we studied complex relationships between environmental variables that describe the local conditions (i.e., grassland environmental state and farming practices) and land cover heterogeneity (i.e., land cover and landscape-wide intensity) of our study area in north-east France; and (ii) estimated the relative effect weight of landscape-wide intensity compared to other local and landscape variables on arthropod communities. We identified 14 taxonomic families, with Lycosidae, Carabidae and Staphylinidae as the families most represented in communities. We have highlighted a positive correlation between the different variables of landscape-wide intensity, as well as a positive correlation between sampled grassland intensity and the quantity of grassland in the landscape. Using Partial Least Squares Path Modelling (PLS-PM) analysis, we observed a positive effect of landscape-wide intensity on arthropod abundance-activity in grassland, indicating a potential concentration effect in the grasslands surrounded by an intensive landscape. Also, we have shown that the effect of landscape-wide intensity was at least as strong as that of other local and landscape variables. Our study is one of the first to consider land cover and farming practices simultaneously at the landscape scale. We demonstrate the importance of considering farming practices at the landscape scale to explain the state of ground-dwelling arthropod communities, and the need to take them into account when designing landscapes that are favourable to biodiversity. We argue that further studies are needed to explain the mechanisms involved in the relationship between arthropod communities and farming practices at the landscape scale.

Current and previous spatial distributions of oilseed rape fields influence the abundance and the body size of a solitary wild bee, Andrena cineraria, in permanent grasslands.

Wild bees are essential pollinators whose survival partly depends on the capacity of their environment to offer a sufficient amount of nectar and pollen. Semi-natural habitats and mass-flowering crops such as oilseed rape provide abundant floristic resources for bees. The aim of this study was to evaluate the influences of the spatial distribution of semi-natural habitats and oilseed rape fields on the abundance and the mean body size of a solitary bee in grasslands. We focused on a generalist mining bee, Andrena cineraria, that forages and reproduces during oilseed rape flowering. In 21 permanent grasslands of Eastern France, we captured 1 287 individuals (1 205 males and 82 females) and measured the body size of male individuals. The flower density in grasslands was quantified during bee captures (2016) and the landscape surrounding grasslands was characterized during two consecutive years (2015 and 2016). The influence of oilseed rape was tested through its distribution in the landscape during both the current year of bee sampling and the previous year. Bee abundance was positively influenced by the flower density in grasslands and by the area covered by oilseed rape around grasslands in the previous year. The mean body size of A. cineraria was explained by the interaction between flower density in the grassland and the distance to the nearest oilseed rape field in the current year: the flower density positively influenced the mean body size only in grasslands distant from oilseed rape. A. cineraria abundance and body size distribution were not affected by the area of semi-natural habitats in the landscape. The spatial distribution of oilseed rape fields (during both the current and the previous year) as well as the local density of grassland flowers drive both bee abundance and the mean value of an intraspecific trait (body size) in permanent grasslands. Space-time variations of bee abundance and mean body size in grasslands may have important ecological implications on plant pollination and on interspecific interactions between pollinators. Specifically, a competition between bee species for nesting sites might occur in oilseed rape rich landscapes, thus raising important conservation issues for bee species that do not benefit from oilseed rape resources.

The impact of management strategies in apple orchards on the structural and functional diversity of epigeal spiders.

Apple orchards are agro-ecosystems managed with high levels of inputs and especially pesticides. Epigeal spider communities were sampled in three seasons using pitfall traps in 19 apple orchards with four different management strategies (abandoned, under organic, Integrated Pest Management or conventional protection) and thus significantly different pesticide usage. The abundance and diversity of the spider communities was the highest in abandoned orchards. Higher diversity and evenness values were the only difference in spider communities from the organic orchards compared to the other commercial orchards. The analysis of five ecological traits (proportion of aeronauts, type of diet, overwintering stages, body size and maternal care), however, clearly showed differences in the spiders from the organic orchards. The spider species in the other commercial orchards were smaller and have higher dispersal abilities. Seven bioindicator species were identified in abandoned orchards, two species in organic ones (only Lycosidae) and one species in conventional orchards (Linyphiidae).

A thesaurus for soil invertebrate trait-based approaches.

Soil invertebrates are known to be much involved in soil behaviour and therefore in the provision of ecosystem services. Functional trait-based approaches are methodologies which can be used to understand soil invertebrates' responses to their environment. They (i) improve the predictions and (ii) are less dependent on space and time. The way traits have been used recently has led to misunderstandings in the integration and interpretation of data. Trait semantics are especially concerned. The aim of this paper is to propose a thesaurus for soil invertebrate trait-based approaches. T-SITA, an Internet platform, is the first initiative to deal with the semantics of traits and ecological preferences for soil invertebrates. It reflects the agreement of a scientific expert community to fix semantic properties (e.g. definition) of approximately 100 traits and ecological preferences. In addition, T-SITA has been successfully linked with a fully operational database of soil invertebrate traits. Such a link enhances data integration and improves the scientific integrity of data.