Hedging against biodiversity loss: Forest herbs' performance in hedgerows across temperate Europe

Questions How do contrasting environmental conditions among forests and hedgerows affect the vegetative and reproductive performance of understorey forest herbs in both habitats? Can hedgerows support reproductive source populations of forest herbs, thus potentially allowing progressive dispersal of successive generations along these linear habitats? Location Hedgerows and deciduous forest patches in agricultural landscapes across the European temperate biome. Methods First, we assessed differences in environmental conditions among forests and hedgerows. Next, we quantified plant performance based on a set of functional life-history traits for four forest herbs (Anemone nemorosa,Ficaria verna,Geum urbanum, Poa nemoralis) with contrasting flowering phenology and colonisation capacity in paired combinations of forests and hedgerows, and compared these traits among both habitats. Finally, we assessed relationships between plant performance and environmental conditions in both habitats. Results All study species showed a higher above-ground biomass in hedgerows than in forests. ForPoa nemoralisandGeum urbanum, we also found a higher reproductive output in hedgerows, which was mainly correlated to the higher sub-canopy temperatures therein. The "ancient forest herb"Anemone nemorosa, however, appeared to have a lower reproductive output in hedgerows than in forests, while forFicaria vernano reproductive differences were found between the two habitats. Conclusions This is the first study on such a broad geographical scale to provide evidence of reproductive source populations of forest herbs in hedgerows. Our findings provide key information on strategies by which forest plants grow, reproduce and disperse in hedgerow environments, which is imperative to better understand the dispersal corridor function of these wooded linear structures. Finally, we highlight the urgent need to develop guidelines for preserving, managing and establishing hedgerows in intensive agricultural landscapes, given their potential to contribute to the long-term conservation and migration of forest herbs in the face of global environmental change.