Influence of soil legacy on the competitive ability of an invasive plant species, [i]Alliaria petiolata[i]
نویسندگان
چکیده
The novel weapons hypothesis posits that biochemical compounds secreted by an invasive species facilitate its success by reducing the performance and survival of other species. This mechanism has been proposed to explain the widespread invasion of the biennial plant, Alliaria petiolata, in North America. Root exudates produced by A. petiolata, a nonmycorrhizal plant, suppress the growth of mycorrhizal fungi, which is expected to strengthen its competitive ability relative to plant species that rely on mycorrhizal fungi for nutrient uptake services. To test this hypothesis, we grew 27 mycorrhizal tree, forb and grass species that are representative of invaded habitats in the absence or presence of competition with A. petiolata in soils with and without a legacy of the invader. A legacy of A. petiolata in soil reduced mycorrhizal colonization of competitor species by >50%. Contrary to expectations, competition between A. petiolata and other species was stronger in control than legacy soil. The invader suppressed the biomass of 19 of 27 competitor species in control soil but only 7 species in legacy soil. This pattern may have been caused by a stronger negative effect of legacy soil on A. petiolata biomass relative to competitor species. The legacy treatment reduced plant available nitrogen by >50% relative to control soil and reduced A. petiolata biomass by 56%, whereas the average biomass of competitor species was reduced by 15%. Our results suggest that despite effective suppression of mycorrhizal fungi, a legacy of A. petiolata in soil does not increase its competitive advantage against other species. Instead, the negative effect of nutrient depletion on A. petiolata was stronger than the negative effect of suppressing mycorrhizal colonization on competitor species. Therefore, the potential for A. petiolata to suppress mycorrhizal plant species through allelopathic effects on mycorrhizal fungi may be weaker than previously expected.
منابع مشابه
Competitive interactions between a nonmycorrhizal invasive plant, Alliaria petiolata, and a suite of mycorrhizal grassland, old field, and forest species
The widespread invasion of the nonmycorrhizal biennial plant, Alliaria petiolata in North America is hypothesized to be facilitated by the production of novel biochemical weapons that suppress the growth of mycorrhizal fungi. As a result, A. petiolata is expected to be a strong competitor against plant species that rely on mycorrhizal fungi for nutrient uptake services. If A. petiolata is also ...
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