A functional classification of herbaceous hedgerow vegetation for setting restoration objectives
Hedgerows are valuable habitats for biodiversity in farmed landscapes. The herbaceous vegetation at the hedge base is an important component of this habitat but its condition in Britain has deteriorated due to a combination of nutrient and pesticide contamination, and inappropriate management or neglect. The condition of herbaceous hedgerow vegetation is included in policy targets for biodiversity conservation, so a strategy is required for its restoration. This vegetation can be highly variable, so a classification of the main types is required to set realistic objectives. Vegetation classifications based on species’ functional characteristics can have more general application that those based on species identity. Using existing datasets from a countrywide survey, a functional classification of herbaceous vegetation from hedgerows in Britain was developed. Cluster analysis of vegetation plots, based on attributes of the species present, produced thirteen vegetation types in six broad groups. These were differentiated by the association of the component species with woodland, grassland or arable habitats and by gradients of soil nutrient status and pH, light availability, disturbance and grazing tolerance. By using species’ ecological characteristics as a basis for the classification, the condition of vegetation can be established and the prevailing environment predicted. From this information, a realistic strategy for restoration can then be determined.