A multidisciplinary approach for studying the invasion mechanisms of the alien tree species Ailanthus altissima (Mill.) Swingle

Ailanthus altissima is a fast growing species, originating in Asia, introduced in Europe for ornamental purposes in the second half of the 18th century. It is currently considered as one of the most invasive woody plant in Europe, so as to be included in the list of invasive alien species of European Union concern. This species shows a strong pioneering character, easily adapting to a wide range of urban, rural and forest ecosystems; it has spread widely in temperate and Mediterranean regions of the world. Winged seeds dispersion, numerous root suckers, as well as adaptability to different soil types and water regimes, have favored the spread of A. altissima, especially in disturbed areas along roads. It also threatens biodiversity through competition, population reduction and habitat modification. Effective management and control of such species is needed to reduce the pressure on ecosystem and limit further spread. Within the frame of the CNR-funded USEit project (Use of operational synergies for the integrated management of invasive alien species in Italy), we used a multidisciplinary approach for investigating A. altissima: we selected several pilot experimental sites across central and southern Italy, with the following aims: i) detecting and mapping the spatial distribution by GIS and remote sensing; ii) investigating the symbiotic relationships between A. altissima and associated mycorrhizae by means of stable isotopes techniques; iii) understanding the role of microbiomes in the Evolution of Increased Competitive Capacity (EICA) of A. altissima by metagenomic sequencing analysis of bacterial and fungal communities colonizing the root system of A. altissima. The original results of this study will be discussed in the frame of the current state of the art of A. altissima mechanisms of invasiveness.