Growth strategy, phylogeny and stoichiometry determine the allelopathic potential of native and non-native plants

Abstract

Secondary compounds can contribute to the success of non-native plant species if they reduce damage by native herbivores or inhibit the growth of native plant competitors. However, there is opposing evidence on whether the secondary com- pounds of non-native plant species are stronger than those of natives. Th is may be explained by other factors, besides plant origin, that aff ect the potential of plant secondary compounds. We tested how plant origin, phylogeny, growth strategy and stoichiometry aff ected the allelopathic potential of 34 aquatic plants. Th e allelopathic potential was quantifi ed using bioassays with the cyanobacterium Dolichospermum fl os-aquae . Th e allelopathic potential showed a strong phylogenetic signal, but was similar for native and non-native species. Growth strategy was important, and emergent plants had twice the allelopathic potential as compared to submerged plants. Furthermore, the allelopathic potential was positively cor- related to the foliar carbon-to-phosphorus (C:P) and total phenolic content. We conclude that eudicot plant species with an emergent growth strategy and high plant C:P ratio exhibit a high allelopathic potential. Unless non-native plant species match this profi le, they generally have a similar allelopathic potential as natives