Analysis of weed dispersal to predict chances of re-colonisation

Negative exponential models provided a good fit of the dispersal curves from the mode outward. In the “arable” treatment, the percentage seedlings - distance regression line fell below 0.5% at 5 m, in the control this level was reached at a distance of about 2 m indicating that long-distance dispersal is a rare event. Cultivation increased the peak distance of the dispersal curves significantly whereas the slope of the curves from the mode outward was hardly affected. Despite different fruit and propagule morphology, seed shadows of both species were very similar. Spatial distribution of the seedlings in the arable treatment occurred along the axis of management and against the prevailing wind direction. The results may help to improve targeting subsidies in agri-environment schemes and assessing the need for re-introduction by sowing.