Alien and native plant establishment in grassland communities is more strongly affected by disturbance than above- and below-ground enemies

Understanding the factors that drive commonness and rarity of plant species and whether these factors differ for alien and native species are key questions in ecology. If a species is to become common in a community, incoming propagules must first be able to establish. The latter could be determined by competition with resident plants, the impacts of herbivores and soil biota, or a combination of these factors.
We aimed to tease apart the roles that these factors play in determining establishment success in grassland communities of 10 alien and 10 native plant species that are either common or rare in Germany, and from four families. In a two-year multisite field experiment, we assessed the establishment success of seeds and seedlings separately, under all factorial combinations of low vs. high disturbance (mowing vs mowing and tilling of the upper soil layer), suppression or not of pathogens (biocide application) and, for seedlings only, reduction or not of herbivores (net-cages).
Na...