Factors affecting field weed and field margin flora on a farm in Essex, UK

Field margins, particularly hedgerows, are important refuges for many species in intensively managed arable landscapes. Their management is influenced by the perception that weed species colonise adjacent crops. Mobile species, such as beetles, are able to use field margins as corridors to recolonise suitable habitat. This study examines whether field margins influence adjacent weed flora, and if there is evidence of the corridor effect of adjacent woodland in margin plant communities. The higher plants present in 51 field margin sites on a large farm in Essex, UK, were recorded. The weed flora in the adjacent arable crops was also assessed in 41 of the sites at 5 and 50 m into the field. Field margin floras were much more diverse than the weed flora, though 25% of species in the margins were also found in the adjacent crops. Most species of the margin were perennials, while arable weeds were dominated by annual species. There was little correlation between field margin and crop flora. The margin flora was correlated with margin structure, which ranged from woodland edge, to shelterbelt, to tall and short hedgerows. Principal component analysis of species indicated woodland sites and those close to woodland were differentiated from hedgerows. Site scores were positively correlated with distance from woodland, possibly indicating site history or colonisation along hedges were important in determining plant communities of field margins.