title: Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems.
abstract: Biological invasions cause ecological and economic impacts across the globe. However, it is unclear whether there are strong patterns in terms of their major effects, how the vulnerability of different ecosystems varies and which ecosystem services are at greatest risk. We present a global meta-analysis of 199 articles reporting 1041 field studies that in total describe the impacts of 135 alien plant taxa on resident species, communities and ecosystems. Across studies, alien plants had a significant effect in 11 of 24 different types of impact assessed. The magnitude and direction of the impact varied both within and between different types of impact. On average, abundance and diversity of the resident species decreased in invaded sites, whereas primary production and several ecosystem processes were enhanced. While alien N-fixing species had greater impacts on N-cycling variables, they did not consistently affect other impact types. The magnitude of the impacts was not significantly different between island and mainland ecosystems. Overall, alien species impacts are heterogeneous and not unidirectional even within particular impact types. Our analysis also reveals that by the time changes in nutrient cycling are detected, major impacts on plant species and communities are likely to have already occurred.
authors: Estación Biológica de Doñana (EBD-CSIC), Avda. Américo Vespucio s/n, Isla de la Cartuja, E-41092 Sevilla, Spain. montse.vila@ebd.csic.es
authors: Montserrat
authors: M
authors: Vilà
authors: José L
authors: JL
authors: Espinar
authors: Martin
authors: M
authors: Hejda
authors: Philip E
authors: PE
authors: Hulme
authors: Vojtěch
authors: V
authors: Jarošík
authors: John L
authors: JL
authors: Maron
authors: Jan
authors: J
authors: Pergl
authors: Urs
authors: U
authors: Schaffner
authors: Yan
authors: Y
authors: Sun
authors: Petr
authors: P
authors: Pyšek