Changes in vegetation composition and distribution within set-aside land.

Abstract

The distribution of flora under set-aside, with respect to distance from the field boundary and the contribution of different sources of origin is discussed using results from an extensive survey of 40 set-aside fields and an intensive study of one field. Perennials and biennials provided most of the cover. Perennial species generally declined with distance from the boundary whilst biennials and annuals increased. A notable exception was the annual Galium aparine which decreased with distance. Data from the intensive study showed three main sources of plant origin. These were, spread by vegetative propagation, e.g., Agrostis stolonifera; an increase in wind-disseminated species including Sonchus and Crepis spp. and a decline in diversity and cover of annuals originating from the seed bank, over the three year study period.