Resistance of plant communities to invasion by tall fescue: An experimental study combining species diversity, functional traits and nutrient levels

Abstract

The grass Festuca arundinacea is often planted for slope stabilisation in South Korea, and is spreading widely beyond the introduction sites. This study used a functional group approach to examine the resistance of plant combinations to invasion by F. arundinacea based on the limiting similarity and diversity-resistance hypotheses, and to elucidate the process of colonisation. The study simulated the environment of construction sites and surrounding areas that might be encountered by expanding populations of F. arundinacea. The role of nutrient condition in the ranking of functional group competitive ability was also examined. Twelve native plant species were categorised into three functional groups using combinations of functional traits. Pairwise (one-to-one competition), multiple (four different neighbouring species) and monoculture experimental settings were designed using two nutrient levels. The Relative Competition Index was used to interpret the competitive effect of neighbouring species on F. arundinacea. Species of the same functional group as F. arundinacea were unable to resist invasion, but annual plants with niche preemption ability could outcompete it. Competitive relationships between native plants and F. arundinacea were explained partially by functional group identity but were inconsistent with the limiting similarity hypothesis and the diversity-interaction. Unforeseen interactions within the artificial communities also produced unexpected effects. In designing artificial plant communities, it is necessary to consider functional traits that reflect the species characteristic of particular periods and indirect effects that modify the interaction between other species.

Keywords

• Functional group identity
• Limiting similarity
• Plant establishment phase
• Community assembly
• Priority effect
• Plant colonisation