Hedgerow age affects the species richness of herbaceous forest plants

Abstract

AbstractQuestionsAre recent hedgerows less rich in forest vascular plants than ancient hedgerows? Does the proximity to potential source populations influence the forest species richness in recent hedgerows? Is there a difference in the dispersal potential of forest specialists found in recent and ancient hedgerows? How similar is the species composition between hedgerows of different ages?LocationSoutheastern Schleswig‐Holstein, Northern Germany.MethodsWe investigated 30 hedgerows in a pairwise design to compare the species composition of ancient and recent hedgerows.ResultsWhile recent hedgerows already function as habitats for herbaceous forest specialists, they contain significantly fewer forest species than ancient hedgerows. Besides hedgerow age proximity to ancient forests, a wide shrub layer, high pH values and a low phosphorus content are also positively associated with the number of forest specialists. The similarity in species composition between recent and ancient hedgerows increases with the age of the recent hedgerow. Epizoochorous dispersal and reproduction by seed favour the colonisation of recent hedgerows by forest species. Most environmental and hedgerow structural parameters do not differ between the age categories except for pH, which is significantly higher in recent hedgerows.ConclusionsAncient hedgerows are important for regional biodiversity, especially as source populations for recent hedgerows, and therefore need to be protected. If the recent hedgerows are managed traditionally, they can over time transform into valuable habitats similar to ancient hedgerows.