The Importance of Field-Margin Location for Maintenance of Food Niches for Pollinators

Understanding the factors that have an impact on the diversity of forage flora in the agricultural landscape is a key issue in the maintenance and control of food niches for pollinators. Field margins are common linear structures in the agricultural landscape. In the present study, we evaluated the factors that exert an impact on the forage flora composition and on the diversity in field margins. The study was conducted in the 2010 - 2011 time period across the agricultural landscape on the Lublin Upland of SE Poland. Data on the forage flora were obtained while making floristic charts along 45 transect plots x 300 m; the total length being 13500 m. Multivariate ordination techniques (PCA and RDA) were employed to analyse forage-flora characteristics. Field margins represent valuable refuge areas for forage-species richness, but not for the abundance of forage species. On field margins, forage-species diversity benefits from the location of natural habitats (forests or meadows), primarily if the distance from these habitats is <1000 m or the field acreage is <10 ha. The shift from heterogeneous habitats to a more homogeneous landscape causes a reduction of forage floral diversity. Due to lack of dense forage-species patches, the promotion of sowing nectariferous and/or polleniferous species seems to be a reasonable management method to enhance the quantitative food niche on field margins and to support the conservation of pollinators in the areas surrounding farms.