PREDATION OF ANNUAL GRASS WEED SEEDS IN ARABLE FIELD MARGINS

Seeds of three species of annual grass weeds (Alopecurus myosuroides, Avena fatua and Bromus sterilis) were placed in field margins around a rable fields in a randomised block split-plot design experiment. The f ield margin vegetation was either sown or naturally regenerated and ei ther cut or uncut. The seeds were either placed in cages designed to e xclude small mammals and birds or were uncaged. The proportion of seed s removed was monitored on 10 occasions and mean seed loss was analyse d. In general, a greater proportion of weed seeds was removed from unc aged trays in uncut swards, suggesting predation by small mammals, whi ch inhabit tall grass. This effect was mainly due to removal of seeds of the two large-seeded species (A. fatua and B. sterilis), with A. fa tua being especially favoured. It is therefore likely that small mamma ls play a role in the population dynamics of major crop weeds by feedi ng on their seeds in field margins, especially when these are dense an d uncut.