1 23 Biological Invasions ISSN 1387-3547 Volume 17 Number 4 Biol Invasions (2015) 17:1095-1108 DOI 10.1007/s10530-014-0780-4 Direct and indirect effects of invasion by the alien tree Ailanthus altissima on riparian plant communities and ecosystem multifunctionality Soraya Constán-Nava, Santiago Soliveres, Rubén Torices, Lluís Serra & Andreu Bonet