Natural colonisation of an open area by Quercus robur L. – From where did the vectors disperse the seed?

We quantified seed flow distances from seed trees of Quercus robur L. into areas with no forest cover based on a population of 147 trees growing next to an open heath land hosting many young oak seedlings. We sampled seedlings along four transects (6-700 m from the source population), and revealed likely parentage of seedlings by microsatellite genotyping data. We found seedlings that fitted the source population at distances up to 700 m, which was the furthest distance from the source population at which seedlings were sampled. However, we estimated that approximately half of the sampled seedlings did not originate from the source population, but must have been recruited from more distant oak populations, growing at least 500 m away. We conclude that the genetic origin and composition of natural regeneration of Q. robur are likely to originate from trees distributed at the landscape level rather than merely trees in the vicinity of the regenerated area. Implications for genetic management are discussed. The quantitative results fit well with qualitative reports of birds transporting acorns several hundred metres away from seed parents.