Importance of Species Replication in Understanding Plant Invasions into North American Grasslands

The global homogenization of the Earth’s biota is expected to increase due to the increase in movement of people and goods between regions, and many introduced species are having a negative economic impact. The increase of introduced species can be thought of as a major global change, because ecosystems throughout the world are now impacted by exotics [1, 2]. Grasslands, which cover roughly 25% of the globe, contain perhaps the most disrupted and homogenized communities in the world. Native grasslands have been lost because of land conversion, and native species have been replaced or displaced with introduced grasses and legumes. Many species were intentionally introduced during the early 20th century to prevent erosion or to improve grazing, and many have undoubtedly done so. However, as management objectives for grasslands have expanded to include wildlife habitat, biodiversity, and C sequestration, it has become critical to understand how introduced species are affecting these new objectives as well. For example, Christian and Wilson [3] found that areas in Saskatchewan, Canada, dominated by the introduced forage grass Agropyron cristatum are sequestering less C into their soils compared to developing native prairie stands with similar land use histories