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Providing evidence to improve practice

Individual study: Hedgerows managed within organic farmland had greater plant diversity than conventional hedgerows in Denmark

Published source details

Aude E., Tybirk K. & Pedersen M.B. (2003) Vegetation diversity of conventional and organic hedgerows in Denmark. Agriculture, Ecosystems & Environment, 99, 135-147

Summary

Organic farming, which primarily aims to avoid the use of pesticides and artificial fertilisers, is one method by which it may be possible to reduce the effects of intensive farming on the environment.  This study investigated plant diversity of comparable hedgerows within organic and conventional farming systems in Denmark.

Thirteen organic hedges on five organic farms and 13 conventional hedges on eight conventional farms (in the same district) were sampled in the southwestern part of Jutland or Weichelian outwash plains in Denmark. All hedgerows had been established 10-14 years ago by the same company; organic hedges were cultivated without pesticides. Fields adjacent to hedges (ley, barley, rape and vegetables) had been managed organically or conventionally since hedgerow establishment; no headlands or unsprayed field margins were present. Farming types only differed in the use of pesticides.

Three pairs of plots (0.5x20 m), one in the centre of the hedgerow and one 0.2m from the field edge, with pairs 20m apart, were sampled per hedge in August 2001. All plant species and species abundance were recorded. A total list of species from 120m on one side of the hedgerows was also obtained by noting supplementary species between plots.

A total of 144 plant species were found, 101 of which occurred in conventional and 128 in organic hedgerows. One protected species was found in an organic hedgerow (broad-leaved helleborine Epipactis helleborine).

There was a significantly greater number of hedge bottom species in organic hedgerows (24-53) than in conventional hedgerows (20-36). Average species richness was significantly higher in organic (15) compared to conventional (13) hedgerows. However, examined separately, boundary samples were more species rich in organic (17) compared to conventional hedges (13), but samples within the hedgerow were not (organic: 14; conventional: 12). Organic hedgerows were significantly richer in weedy, ruderal and semi-natural species; there was no difference in abundance of bryophytes or forest species.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: doi:10.1016/S0167-8809(03)00146-4