The invasion of common milkweed (Asclepias syriaca) in sandy old-fields - is it a threat to the native flora?

摘要

Questions: Common milkweed (Asclepias syriaca L.) is an invasive 'super species' that has invaded extensive areas in Europe, forming novel ecosystems. One study has reported neutral effects of common milkweed on the native flora of sand dune grasslands in Hungary after the removal of invasive pine plantation. However, the effects of common milkweed on native flora more generally are unknown. Focusing on the potential effect of milkweed, we tested the following hypotheses: (1) the cover of native grassland species decreases with increasing cover of common milkweed; and (2) native species with low specific leaf area (SLA), height, seed mass and clonal spreading ability (i.e. low competitive ability) are more likely suppressed by milkweed compared with natives with high competitive ability.