Competitive Interactions between Two Non-Native Species (Alliaria petiolata [M. Bieb.] Cavara & Grande and Hesperis matronalis L.) and a Native Species (Ageratina altissima [L.] R.M. King & H. Rob.).

Kassandra R Paulus,Jordan M Marshall

doi:10.3390/plants11030374

Abstract

Alliaria petiolata and Hesperis matronalis are wide-ranging non-native species in North America. Ageratina altissima is native to North America but has become a concern as an invasive species in Asia. A replacement series experiment was established to quantify the competitive interactions between these three species and to rank their relative competitiveness with each other. We assessed leaf count, chlorophyll content, and aboveground biomass with comparisons between replacement series mixtures and competition species. Overall leaf count and aboveground biomass were greatest in A. altissima and chlorophyll content was lowest in A. petiolata. Chlorophyll content and aboveground biomass were lower for A. altissima in competition with A. petiolata compared to H. matronalis. Leaf count for A. petiolata was lower in competition with A. altissima compared to H. matronalis. Aboveground biomass for H. matronalis was lower in competition regardless of the species compared to monoculture. There were also negative trends in biomass for A. petiolata in competition with increasing neighbors. However, for A. altissima, the negative trend in biomass was with A. petiolata, H. matronalis did not negatively affect A. altissima biomass. Our rank order of competitiveness was A. altissima > A. petiolata >> H. matronalis.

Highlights

Competitive ability and impacts on native communities, especially biomass accumulation, are important characteristics to understanding overall invasiveness of a given species [1]
There was no significant difference between the three species mortality with series mixtures as a random effect
While Ageratina altissima is native to North America, it was become a concern invading disturbed forests in South Korea [33]

Summary

Introduction

Competitive ability and impacts on native communities, especially biomass accumulation, are important characteristics to understanding overall invasiveness of a given species [1]. The existing community of plants has influence on successful establishment, overcoming the lag between cryptic and apparent, and subsequent dominance of non-native species invading an ecosystem. When population inertia from the non-native species is high due to adaptations overcoming establishment hurdles (i.e., non-viable offspring) and Allee effects (i.e., failure to locate mates), the likelihood of invasion outweighs the likelihood of exclusion [3]. Those traits that facilitate establishment may translate to competitive ability. Other traits add competitive advantage, such as early leaf phenology, seed production and dispersal, allelopathy, and biomass, leading to interrelated characteristics improving competitive success [10]

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