title: Ecological application of biotic resistance to control the invasion of an invasive plant,Ageratina altissima.
abstract: Biotic resistance is the ability of species in a community to limit the invasion of other species. However, biotic resistance is not widely used to control invasive plants. Experimental, functional, and modeling approaches were combined to investigate the processes of invasion byAgeratina altissima(white snakeroot),a model invasive species in South Korea. We hypothesized that (1) functional group identity would be a good predictor of biotic resistance toA. altissima, whereas a species identity effect would be redundant within a functional group, and (2) mixtures of species would be more resistant to invasion than monocultures. We classified 37 species of native plants into three functional groups based on seven functional traits. The classification of functional groups was based primarily on differences in life longevity and woodiness. A competition experiment was conducted based on an additive competition design withA. altissimaand monocultures or mixtures of resident plants. As an indicator of biotic resistance, we calculated a relative competition index (RCIavg) based on the average performance ofA. altissimain a competition treatment compared with that of the control where only seeds ofA. altissimawere sown. To further explain the effect of diversity, we tested several diversity-interaction models. In monoculture treatments, RCIavgof resident plants was significantly different among functional groups but not within each functional group. Fast-growing annuals (FG1) had the highest RCIavg, suggesting priority effects (niche pre-emption). RCIavgof resident plants was significantly greater in a mixture than in a monoculture. According to the diversity-interaction models, species interaction patterns in mixtures were best described by interactions between functional groups, which implied niche partitioning. Functional group identity and diversity of resident plant communities were good indicators of biotic resistance to invasion by introducedA. altissima, with the underlying mechanisms likely niche pre-emption and niche partitioning. This method has most potential in assisted restoration contexts, where there is a desire to reintroduce natives or boost their population size due to some previous level of degradation.
authors.affiliation: School of Civil and Environmental Engineering Yonsei University Seoul Korea.
authors.forename: Chaeho
authors.initials: C
authors.lastname: Byun
authors.affiliation: School of Biological Sciences Seoul National University Seoul Korea.
authors.forename: Eun Ju
authors.identifier: 0000-0003-3669-9004
authors.initials: EJ
authors.lastname: Lee
keywords: Ageratina altissima; Eupatorium rugosum; diversity–interaction model; functional group; invasive plant management; priority effect