Integrated conservation of a rare threatened plant and the community of its natural pollinators: the Life+ PP-ICON project (LIFE09/NAT/IT000212)

About 90% of angiosperms profit from animal pollination for reproduction. The mutualistic pollination interactions are beneficial to plants and animals but also benefit humanity, through crop productivity and ecosystem health. Pollination systems are under increasing threat from anthropogenic sources, including habitat fragmentation, changes in land use, modern agricultural practices, use of pesticides and herbicides. Rare plants are commonly more sensitive to habitat loss and fragmentation and often occur in small populations, which may decrease the attractiveness to pollinators and reduce pollinator service. The PP-ICON project (Plant Pollinator Integrated CONservation approach: a demonstrative proposal, http://www.pp-icon.eu) focuses on the conservation of a locally rare plant (Dictamnus albus L.) and the community of its natural pollinators. At present, European wild populations of dittany are declining because of scarcity of pollination service; in addition, suitable habitats (woodland fringes and clearings) are becoming rare due to land-use changes resulting from the abandonment of traditional agro-silvo-pastoral activities. Wild pollinators are facing a widespread decline, mainly due to climatic changes, soil use changes, habitat fragmentation and pollution, which cause a scarcity of floral resources and nesting sites. The main objectives of this 4-year project are to ensure the persistence of an isolated population of D. albus, located in a protected area (Parco Regionale dei Gessi Bolognesi e Calanchi dell'Abbadessa) included in the Natura2000 network (SIC-SPA IT4050001), and to restore the community of its natural pollinators. These integrated techniques could be applied for the conservation of other plant species and respective pollinators. Actions focus on habitat management, pollinators safeguard, stakeholders awareness and dissemination. Habitat has been managed in order to establish the best environmental condition for the persistence of the target population. At the same time effective pollinators of dittany have been identified, in order to artificially rear and introduce them in the area, and suitable nesting sites have been provided. The maintenance of introduced pollinators will be assured by the growing of autochthonous nectariferous plant species, which are planted in the area. The fitness of the plant and the pollinating fauna are monitored every year, in order to assess the success of conservation actions, and check for the need of eventual redirections. After one year of implementation, preliminary project results show a positive output of the intervention on the wood, with an increase of flowering in the newly created clearings. Despite being visited by many insect species, belonging to different orders, data indicate that only medium-large bee species (Habropoda tarsata, Xylocopa violacea, Bombus spp., Eucera spp.) effectively pollinate the flowers of D. albus. By contrast, small halictid bees frequently visit the flowers without touching the stigmatic surface, behaving as nectar or pollen thieves. Based on these results, conservation actions have been redirected. Small nesting holes have been excluded in the artificial nests placed in the area, and species visited exclusively by large bees (e.g. Lathyrus latifolius) have been added to the list of nectariferous plants with scalar flowering period to be planted in the area: collected seeds will be germinated in the Botanic Garden for following plantation