Data from: Competitive ability of native and alien plants: effects of residence time and invasion status

Competition is commonly thought to underlie the impact of plant invasions.
However, competitive effects of aliens and competitive response of natives
may also change over time. Indeed, as with time the novelty of an invader
decreases, the accumulated eco-evolutionary experience of resident species
may eventually limit invasion success. We aimed to gain insights on
whether directional changes in biotic interactions over time, or more
general differences between natives and aliens, for instance resulting
from an introduction bias, are relevant in determining competitive
ability. We conducted a pairwise competition experiment in a
target-neighbour design, using 47 Asteraceae species with residence times
between 8-12,000 years in Germany. We first tested whether there are
differences in performance in intraspecific competition among invasion
status groups, that is casual and established neophytes, archaeophytes, or
native species. We then evaluated whether competitive response and effects
depend on residence time or invasion status. Lastly, we assessed whether
competitive effects influence range sizes. We found only limited evidence
that native target species tolerate neighbours with longer potential
coexistence times better, whereas differences in competitive ability were
mostly better explained by invasion status than residence time. Although
casual neophytes produced most biomass in intraspecific competition, they
had the weakest per-capita competitive effects on natives. Notably, we did
not find differences between established neophytes and natives, both of
which ranked highest in interspecific competitive ability. This lack of
differences might be explained by a biased selection of highly invasive or
rare native species in previous studies, or because invasion success may
result from mechanisms other than interspecific competitive superiority.
Accordingly, interspecific per-capita competitive effects did not
influence range sizes. Further studies across a broader range of
environmental conditions, involving other biotic interactions that
indirectly influence plant-plant interactions, may clarify when
eco-evolutionary adaptations to new invaders are a relevant mechanism.