Reproductive ecology and conservation of the rare Dictamnus albus L.

D. albus is a long-lived perennial herb found at xerothermic woodlands fringes and in (semi)natural grasslands, in the southern regions of Europe and Central-Eastern Asia (Hensen et al., 2005). At present, european populations are declining due to land-use changes and fragmentation: suitable habitats are becoming rare, often separated by significant distances and surrounded by agricultural landscapes (Hensen et al., 2006). In Italy it reaches its southern distribution limit. We studied the reproductive ecology of D. albus with the aim of describing plant-pollinator system from both plant and pollinator perspectives, and of assessing factors that limit its persistence. The mating system and reproductive success were investigated, showing potential self-compatibility. Combining data on nectar analysis along the raceme and pollinators’ behaviour, resulted a bottom-to-top pattern of visits by major pollinators, following a nectar gradient on the raceme. Intra-flower self-pollination is prevented by protandry and herkogamy, while the nectar-induced sequential pattern of pollinator visits avoids geitonogamy and tends to maximize pollen export, promoting outcrossing (Fisogni et al., 2011). A pollen limitation experiment was performed during two consecutive years: limitation in visits and pollen receipt was found to be potentially significant. A three-years demography study showed lower abundance of plants under wood canopy compared with edges; moreover, no flowering plants and very few seedlings were observed in mature wood, indicating an almost null recruitment success and a threat to long-term survival. Based on these results, a LIFE+ Nature & Biodiversity project: Plant-Pollinator Integrated CONservation approach: a demonstrative proposal (www.pp-icon.eu) has been recently financed (LIFE09/NAT/IT000212). The main objectives of this project are to ensure the persistence of an isolated population of D. albus and to restore the community of its natural pollinators. The integrated techniques proposed could be applied for the management of other european populations of D. albus, as well as for the conservation of several plant species and respective pollinators that are facing the same risks in Europe.