Published online by Cambridge University Press: 01 December 2009
European gorse (Ulex europaeus L.) is a spiny shrub that grows spontaneously in the understorey of forests and heathlands in western Europe. Gorse is a pioneer species and forms large seed banks that can persist for a long time while buried deeply in the soil. Although many studies have been conducted on gorse seed banks in invasive contexts and in scrubland ecosystems, few data are available on forests in a native context. The aim of the present study was thus to report on the variability of seed-bank density in ‘critical’ stages in the forest management of pine stands (five stands) in south-western France. We examined variations in the number of gorse seeds as a function of soil depth but also of the presence and abundance of adult gorse in the understorey. Seed-bank density did not show a clear decrease in seed number with pine stand age, principally because gorse also appears to be able to establish itself in mature pine stands, probably thanks to local disturbances. In the pine stands in our study, the presence and abundance of seeds in the soil appeared to depend mostly on the presence of adult gorse as seeders in the understorey. Finally, we observed that, contrary to what has generally been found in scrubland ecosystems, most gorse seeds were located in the 5–10 cm soil layer rather than in the 0–5 cm soil layer. This depletion of the first 5 cm may be linked to seed germination that was not compensated for by the production of new seeds.