title: Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops.
abstract: The Farm Scale Evaluations (FSEs) showed that genetically modified herbicide-tolerant (GMHT) cropping systems could influence farmland biodiversity because of their effects on weed biomass and seed production. Recently published results for winter oilseed rape showed that a switch to GMHT crops significantly affected weed seedbanks for at least 2 years after the crops were sown, potentially causing longer-term effects on other taxa. Here, we seek evidence for similar medium-term effects on weed seedbanks following spring-sown GMHT crops, using newly available data from the FSEs. Weed seedbanks following GMHT maize were significantly higher than following conventional varieties for both the first and second years, while by contrast, seedbanks following GMHT spring oilseed rape were significantly lower over this period. Seedbanks following GMHT beet were smaller than following conventional crops in the first year after the crops had been sown, but this difference was much reduced by the second year for reasons that are not clear. These new data provide important empirical evidence for longer-term effects of GMHT cropping on farmland biodiversity.
authors.affiliation: Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK. lgf@ceh.ac.uk
authors.forename: L G
authors.initials: LG
authors.lastname: Firbank
authors.forename: P
authors.initials: P
authors.lastname: Rothery
authors.forename: M J
authors.initials: MJ
authors.lastname: May
authors.forename: S J
authors.initials: SJ
authors.lastname: Clark
authors.forename: R J
authors.initials: RJ
authors.lastname: Scott
authors.forename: R C
authors.initials: RC
authors.lastname: Stuart
authors.forename: C W H
authors.initials: CW
authors.lastname: Boffey
authors.forename: D R
authors.initials: DR
authors.lastname: Brooks
authors.forename: G T
authors.initials: GT
authors.lastname: Champion
authors.forename: A J
authors.initials: AJ
authors.lastname: Haughton
authors.forename: C
authors.initials: C
authors.lastname: Hawes
authors.forename: M S
authors.initials: MS
authors.lastname: Heard
authors.forename: A M
authors.initials: AM
authors.lastname: Dewar
authors.forename: J N
authors.initials: JN
authors.lastname: Perry
authors.forename: G R
authors.initials: GR
authors.lastname: Squire
mesh_terms: D000383:Agriculture; D027461:Beta vulgaris / Q000235:genetics / Q000502:physiology; D044822:Biodiversity; D029741:Brassica rapa / Q000235:genetics / Q000502:physiology; D018556:Crops, Agricultural / Q000235:genetics / Q000502:physiology*; D053209:Herbicide Resistance / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology*; D006109:Poaceae / Q000254:growth & development*; D012639:Seeds / Q000254:growth & development; D003313:Zea mays / Q000235:genetics / Q000502:physiology