Invasive plant species can negatively alter soil communities.

Multiple mechanisms enable invasive species to suppress native species

Alison E. Bennett, Meredith Thomsen, and, Sharon Y. Strauss

Published online before print 17 June 2011, doi:10.3732/ajb.1000177Am. J. Bot. July 2011 vol. 98no. 7 

The latest research by Dr. Alison Bennett and Dr. Sharon Strauss at the University of California, Davis and Dr. Meredith Thomsen at the University of Wisconsin, La Crosse has shed light on some previously unknown effects of invasive species. Invasive plants are a significant threat to ecosystem biodiversity throughout the world.

Previous studies have focused on the effect of individual factors, such as release from native enemies, disturbance, or allelopathy, but the interactions among these factors have not been studied. Here the researchers studied the effects of four primary mechanisms that potentially contribute to the success of invasive velvetgrass, Holcus lanatus. Direct competition, changes to the soil community, indirect competition due to changes in herbivore feeding, and interference competition due to allelopathy were put under the scanner.

The researchers found that H. lanatus clearly hindered the germination, growth, and establishment of E. glaucus. The presence of H. lanatus altered soil communities. The researchers say the negative impact persists even after H. lanatus is removed. The researchers contend that the removal of competitors without attention to soil legacies may result in failure of native species to re-establish.