The effect of provenance on the performance of Crataegus monogyna in hedges.
Grants for wildlife enhancement in the British Isles, UK have supported the widespread planting of new hedges along field margins. However, much of the planted material, particularly of hawthorn Crataegus monogyna, has been obtained from the continental mainland of Europe. There is a need to assess the implications of this practice for hedgerow performance and for the conservation of indigenous genetic variation. One local ecotype and eight commercial provenances (four British and four continental European) of hawthorn were planted in an experimental hedge at both an exposed upland site and a sheltered lowland site. Sections of hedge were planted with or without fencing and with or without mulching in all combinations. Growth and thorniness were assessed over 3 years, and phenology and disease over 2 years. At both sites, the most locally obtained provenance had the latest bud-burst, exhibited the least severe symptoms of mildew and was the most thorny. It also showed the greatest height increment at the upland site, but was relatively slow-growing at the low-land site. An imported Hungarian provenance had early bud-burst, showed a high growth rate and suffered the most severe mildew. A commercially obtained British native provenance was aberrant in its extremely early bud-burst and other attributes comparable with the Hungarian provenance, indicating the possibility of misidentification at some stage of production or supply. In the absence of fencing, at the upland site hawthorn mortality was 100% compared with only 3% at the lowland site. In fenced plots there was approximately 320% greater growth when mulching was used. The results suggest that for greater establishment success and hence cost benefits in hedge planting, as well as for greater environmental benefits, there should be closer matching of hawthorn provenance to the planting site. The use of commercial material has demonstrated that locally provenanced material can be superior to any commercially available material, and that the current state of the commercial sector is insufficient to enforce the necessary controls over provenance of material used for hedge renovation.