The distribution pattern of ragweed (Ambrosia elatior) was studied in dry habitats of the Great Hungarian Lowland. The role of disturbance and propagule availability in the occurrence and abundance of ragweed were studied experimentaly.
Ragweed reaches the highest abundance in arable fields and old-fields abandoned in the last few years. During the secondary succession of old fields its abundanse decreases. Its occurrence is limited by the need for soil disturbance. Undisturbed areas it cannot reach high abundance, even if there are no propagule limitation and the environmental conditions are suitable.