THE IMPACT OF SOME FIELD BOUNDARY MANAGEMENT-PRACTICES ON THE DEVELOPMENT OF DIPSACUS-FULLONUM L. FLOWERING STEMS, AND IMPLICATIONS FOR CONSERVATION

Dipsacus fullonum (Dipsacus sylvestris) is a native biennial, common i n the UK agricultural landscape, providing floral resources for potent ial crop pollinators, natural enemies of cereal pests, and other insec ts. Ln north America, the plant has become established as an invasive alien, threatening to displace native species of sensitive conservatio n status. Surveys of farmland in Cambridgeshire, UK, over a three year period indicated that the plant's distribution along field boundaries rendered it prone to damage by routine boundary management practices. In experiments, some stems cut before flowering regrew but produced s ignificantly fewer flowerheads than uncut plants; stems cut during or after flowering produced no new flowerheads. Seeds borne in flowerhead s of plants cut during or immediately after flowering failed to germin ate. Although the local persistence of D. fullonum did not appear to b e threatened by routine management in this study, resulting loss of fl oral resources has implications for the plant's insect fauna. Flexibil ity in the timing of boundary management could alleviate potential neg ative effects on beneficial insects in UK agroecosystems. Knowledge of the suppression of seed production by appropriately timed stem-cuttin g might be incorporated into control programmes in systems where the p lant is an invasive alien. (C) 1998 Elsevier Science B.V.