Direct and indirect effects of the alien tree Ailanthus altissima
Ailanthus altissima (Simaroubaceae) (EPPO list of invasive alien plants) is a deciduous tree species native to China and North Vietnam and a widespread alien in the EPPO region. In this present study the authors evaluated the direct and indirect effects of A. altissima invasion on riparian plant communities and ecosystem multifunctionality. The study was conducted in the Mediterranean area of Southeastern Spain. Ten 10 x 10 m control plots were established where A. altissima was absent along with ten 10 x 10 m infested plots. Within each plot the percentage cover and species richness of vegetation was assessed in 40 quadrats (0.5 x 0.5 m). Understory plant biomass was evaluated in 5 quadrats in each plot. Soil samples were collected in each plot and tested in the laboratory for soil enzyme activity and soil nutrients. Structured equation modeling was used to separate direct and indirect effects of A. altissima on ecosystem multifunctionality. The presence of A. altissima was associated with lower plant species richness, lower phylogenetic diversity and lower ecosystem multifunctionality.
Constàn-Nava S, Soliveres S, Torices R, Serra L, Bonet A (2015) Direct and indirect effects of invasion by the alien tree Ailanthus altissima on riparian plant communities and ecosystem multifunctionality. Biological Invasions 17, 1095-1108.