Responses of plants, earthworms, spiders and bees to geographic location, agricultural management and surrounding landscape in European arable fields

Abstract

Farmland species provide key ecological services that support agricultural production, but are under threat from agricultural intensification and mechanization. In order to design effective measures to mitigate agricultural impact, simultaneous investigations of different taxonomic groups across several regions are required. Therefore, four contrasting taxonomic groups were investigated: plants, earthworms, spiders and bees (wild bees and bumblebees), which represent different trophic levels and provide different ecological services. To better understand underlying patterns, three community measurements for each taxonomic group were considered: abundance, species richness and species composition. In four European regions, ten potential environmental drivers of the four taxonomic groups were tested and assigned to three groups of drivers: geographic location (farm, region), agricultural management (crop type, mineral nitrogen input, organic nitrogen input, mechanical field operations and pesticide applications) and surrounding landscape in a 250 m buffer zone (diversity of habitats in the surroundings, proportion of arable fields and proportion of non-productive, non-woody habitats). First, the variation in abundance, species richness and species composition from 167 arable sites was partitioned to compare the relative contribution of the three groups of drivers (geographic location, agricultural management and surrounding landscape). Second, generalized linear mixedeffects models were applied to estimate the effect of the individual explanatory variables on abundance and species richness. Our analysis showed a dominant effect of geographic location in all four taxonomic groups and a strong influence of agricultural management on plants, spiders and bees.The effect of the surrounding landscape was of minor importance and inconsistent in our data. We conclude that in European arable fields, the avoidance of mineral nitrogen and pesticides is beneficial for biodiversity, and that species protection measures should take into account regional characteristics and the community structure of the investigated taxonomic groups.

Intense ranchland management tips the balance of regional and local factors affecting wetland community structure

“…However, land use effects varied among taxa and community metrics, underlining the importance of studying multi-taxon responses and several measures of composition (Lüscher et al, 2014;Zulka et al, 2014). For instance, vegetation was more often affected by local conditions while macroinvertebrates were more often affected by regional factors.…”

Gains to species diversity in organically farmed fields are not propagated at the farm level

“…There was a striking correspondence between gains to species richness and organism abundance across all regions and taxonomic groups. Although this is not surprising and is a well-known property of species richness 25,30,39 , it shows that a higher abundance of individuals is likely the most important effect of organic farming on species richness. Hence, organic farming is not significantly increasing the number of species present in a given number of individuals but sustains a higher number of individuals in a given sampling unit.…”

“…To address the challenge of the intangible nature of 'biodiversity' as a whole, we analysed organism abundance, species richness and species evenness in four taxonomic groups: plants, earthworms, spiders and bees. The groups were selected to represent different habitat compartments (soil, soil surface and above-ground structures), trophic levels, mobility and expected responses to agricultural management 15,16,19,20,29,30 . To cope with the heterogeneity of agriculture, we sampled species in 205 farms in twelve contrasting regions in Europe and Africa using standardized methods ( Fig.…”

How to implement biodiversity-based agriculture to enhance ecosystem services: a review

“…With a similar objective, Herzog et al (2012) developed a core set of farmland habitat indicators estimated with a standard mapping procedure based on a generic system of habitat definitions, itself based on management intensity and Raunkiaer's plant life forms (Raunkiaer 1934). This indicator set has been used to link farmland habitats (seminatural and cultivated) to functional biodiversity, e.g., wild bees as pollinators, spiders as generalist predators, and earthworms as soil engineers, and assess the main drivers of species richness and diversity of these organisms in agroecosystems (e.g., Lüscher et al 2014;Schneider et al 2014). In a similar approach, including a more precise description of seminatural habitats at the farm level and a classic coarser description at the landscape level, Sarthou et al (2014) demonstrated that explanatory variables of seminatural habitats shaping different communities of overwintering natural enemies (i.e., all classic generalist and aphidophagous natural enemies of pests, including spiders, lacewings, Hymenopteran parasitoids, rovebeetles, and predatory species of ground beetles, hoverflies, and ladybugs) have a decreasing influence from the local level (field) to the "mid-distant landscape" (60-120 m) to the "distant landscape" (120-500 m).…”