1. ¹Center for Rhizosphere Biology, Colorado State University, Fort Collins, CO, USA
2. ²USDA-ARS, Soil-Plant-Nutrient Research Unit, Fort Collins, CO, USA

Correspondence: JM Vivanco, Horticulture and Landscape Architecture, Center for Rhizosphere Biology, Colorado State Unniversity, 1173 Campus Delivery, Fort Collins, CO 80523, USA. E-mail: J.Vivanco@colostate.edu

Received 4 July 2007; Revised 3 September 2007; Accepted 3 September 2007; Published online 11 October 2007.

Abstract

Interactions between plants and soil microbes are important determinants of both above- and belowground community composition, and ultimately ecosystem function. As exotic plants continue to invade and modify native plant communities, there has been increasing interest in determining the influence of exotic invasives on native soil microbial communities. Here, using highly sensitive molecular techniques, we examine fungal abundance and diversity in the soil surrounding a particularly aggressive invasive plant species in North America, Centaurea maculosa Lam. In mixed stands, we show that this invasive weed can alter the native fungal community composition within its own rhizosphere and that of neighboring native plants. At higher densities, the effect of C. maculosa on native soil fungal communities was even greater. Our results demonstrate that this invasive weed can have significant effects not only on visible aboveground biodiversity but also on the native soil microbial community that extends beyond its rhizosphere.