Successful exotic invaders: a phylogentic comparison of soil community feedback and aboveground herbivore performance

Ecosystems worldwide are increasingly being invaded by plants from exotic origin. It has been stressed that these invaders perform better than similar native species in the invaded communities. Although plant invasions have taken place for more than a century, the mechanisms explaining the success of invaders are not well understood yet. Considerable attention has been paid to the role of plant specific traits and natural control by aboveground herbivores, both in the original and new ranges of the invading plants. Release from belowground or aboveground natural enemies has been widely stressed as the biggest advantage for invaders to become successful. These invasive plants are characterized by local dominance in their new community, thereby displacing native species, and strong dispersal reaching high abundances. Also when plants spread faster than their natural enemies or than the enemies of their enemies, multi-trophic interactions can become, at least temporarily, disrupted. These changes in relations may create invasion opportunities for species within geographical regions. In order to understand how exotic plant species change their soil environment relative to that of native species we conducted a phylogenetically controlled experiment with cross comparison of plants grown in self conditioned soil and soil conditioned by other species. The presentation will include feedback effects from the soil community to the performance of plants. In addition, we will show how native and non-native plants may differ in their host suitability to generalist aboveground invertebrate herbivores and how plant-soil feedback of native and non-native plants may influence interactions between plants and the aboveground herbivores.