Is there a reliable correlation between hedgerow density and agricultural site conditions?

The aim of this study was to determine whether the number of landscape elements and site conditions are reliably associated. As example, we considered the distribution of hedgerows on sites of varying agricultural quality. Experiments were carried out on two spatial levels: the first as the "natural unit", characterised as a region having nearly homogeneous site conditions; the second as the entire area of Baden-Wuerttemberg, comprising various natural units. The association between ecological and economic information was analysed statistically. We observed that a considerable correlation between "agricultural site quality" and "hedgerow density" (-0.63) existed only on the spatial level of the natural unit, but here exclusively in the case of the less-favoured natural unit. In contrast, no such correlation was found on the spatial level of a federal state (Baden-Wuerttemberg). Although there is still a need for improving indicator deriving processes these results indicate that agri-environmental programmes concerning biotope protection would be best implemented on an administrative level, whose size and landscape homogeneity is comparable to that of the natural units.