Invasive non-native species have significant negative ecological and economic impacts. The negative ecological impacts have been widely reported; invasive non-native species may predate or out-compete native species, be the vectors of disease and affect ecosystem services.

In the Journal of Ecology, a team of researchers from the Czech Republic, have published one of the rare studies that actually quantify community-level effects of invasive non-native plants.

The researchers assessed the effects of thirteen invasive non-native plant species on a range of plant communities by measuring species richness, diversity and evenness in invaded and uninvaded plots. Eleven of the thirteen invading plant species reduced species richness, diversity and evenness. The decrease in species richness in invaded plots is primarily due to the identity of the invading plant species. The decrease in diversity and evenness is primarily due to the height and cover of the invading non-native species and the differences in height and cover between the native and non-native plants.

This study indicates the need for conservation managers to consider that the effects of invasive plants on native plant communities differs between invading plant species and that the characteristics rather than species identity of the invading plant affects species diversity and evenness.

Original article: Hejda, M., Pyšek, P. and Jarošík, V. (2009) Impact of invasive plants on the species richness, diversity and composition of invaded communities. Journal of Ecology, 97, 393-403.
For further information on invasive non-native species please see POSTnote 303 written by the 2008 BES-POST fellow.