Dispersal and habitat quality as constraining factors for herbaceous forest species in an ancient hedgerow network

Summary

Reports on the importance of hedgerows for conservation of vulnerable herbaceous forest (HF) species are conflicting. The main objective of the present study was to throw light on the possible role of hedgeworks functioning as dispersal corridors for HF species. Seventy-four plots were laid out in a hedgerow network close to ancient woodlands. A total of 30 HF species were found. Richness and cumulated frequency of HF species as well as the frequencies of six selected forest herb species were compared with hedgerow age, width, distance to woodland and weighted Ellenberg indicator values for light, soil moisture, soil pH and soil fertility. Distance to woodland followed by light and soil moisture were the most important explanatory variables of HF species distribution. Dispersal limitation appeared to constrain the distribution of HF species in the hedgerow network but habitat quality was also a restricting distribution factor. A corridor effect was revealed and we conclude that old hedgerow networks may play an important role in the agrarian landscape as a dispersal corridor for HF species that are threatened by habitat fragmentation and nutrient enrichment.