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1. Establishment success of non-native invasive species is often attributable either to habitat invasibility or inherent species traits. In this study we explored the interplay between these two factors in the establishment, expansion and plasticity in growth of the clonally reproducing invasive weed mugwortArtemisia vulgarisin two contrasting habitats, as well as the potential management practice of monthly mowing.2. We investigated resource allocation patterns and spatial distribution of ramets originating from two naturalized populations over a 3-year period. Ramets from these morphologically distinct populations were transplanted into each of two contrasting habitats to determine the invasive potential of these populations and the relative resistance of each habitat to invasion.3. Total ramet production, average ramet height and spatial distribution patterns differed significantly between the two populations, but the degree of variation in the response was habitat dependent. There were no interpopulation differences in total biomass production. Plastic responses in resource allocation patterns, spatial distribution of ramets and relative growth rates were observed, demonstrating differences in invasive potential between the two mugwort populations.4. The two habitats differed in invasibility. This could have been the result of differences in community structure, competition for available resources, disturbance and/or invader traits. In addition, monthly defoliation (mowing) reduced mugwort ramet production by as much as 90% and as little as 10%.5. Synthesis and applications.This study demonstrates that variation exists in habitat invasibility, and that intraspecific variation in growth patterns occurs in mugwort. The interaction between habitat traits and species characteristics was found to be important when determining invasion success. We also demonstrated that monthly mowing following the introduction of mugwort can substantially decrease the rate of spread of this clonal species, which may provide an effective management opportunity both for this species and for other clonal invaders.Journal of Applied Ecology(2005)42, 567–576doi: 10.1111/j.1365-2664.2005.01030.x [ABSTRACT FROM AUTHOR]

The alien vine Vincetoxicum rossicum (Kleopow) Barbar. (Asclepiadaceae) is a major concern in natural areas of the Lower Great Lakes Basin. Reproduction in this perennial occurs largely by polyembryonic seeds that mature from August to November. Many seeds produced in autumn germinate the following spring, but the germinability of seeds produced in late summer is unknown. The influence of parent plant light environment on seed characteristics in this species is also poorly understood. We examined the characteristics of V. rossicum seeds harvested in late August and early November 2002 from three habitats in central New York State, USA, differing in light availability. Site had a significant effect on seed weight and germination percentage, but not on the number of embryos germinating per seed or radicle length. Seeds produced in the shaded habitat in August weighed significantly more and had lower germin ability than seeds produced in an adjacent open habitat, but this was not observed in a second open habitat. The probability of germination decreased with seed size for seeds ranging from 2 to 8 mg. For the open sites, fresh seeds produced in August had approximately double the germination percentages of those produced in November. However, for all sites, germination following 18 weeks of cold storage was greatest for seeds harvested in November. The probability of multiple embryos germinating was influenced by seed weight. The nature of this relationship varied by site, but not by harvest date or storage duration. Larger seed size resulted in longer total radicle length after 7 d, regardless of site. [ABSTRACT FROM AUTHOR]