Table 1 Overarching research questions and specific predictions tested using our mesocosm experiment.
From: Exotic plants accumulate and share herbivores yet dominate communities via rapid growth
Category | Overarching research question (numbered) and specific predictions (lowercase letters) |
|---|---|
Direct plant–herbivore interactions | 1. Compared with native plant species and native-dominated communities, do exotic plant species and exotic-dominated communities experience weaker (i.e., enemy release; Fig. 1A) or stronger (i.e., biotic resistance; Fig. 1B) interactions (measured as herbivore diversity, biomass and damage) with native and exotic herbivores? (a) Compared with native plants, exotic plants and exotic-dominated communities accumulate less native herbivore biomass (both total and proportional to plant biomass) and more exotic herbivore biomass. (b) Exotic plants and exotic-dominated communities host fewer herbivore species than natives. (c) Exotic plants and exotic-dominated communities suffer lower herbivore damage than natives. |
Net herbivore impact on plant biomass and exotic dominance | 2. Do exotic plants experience lower or higher proportional reductions in biomass production from herbivores than native plants (i.e., enemy release or biotic resistance translate into impacts on plant fitness; Figs. 1A, B)? (a) Exotic plants experience lower proportional reductions in total, belowground and aboveground biomass production from herbivores compared to natives. (b) Exotic plants make up a disproportionate proportion of plant community biomass, especially when herbivores are present. |
Indirect plant–herbivore interactions | 3. Do exotic plants have higher potential to exert and lower potential to receive apparent competition than native plants, with consequences for plant biomass (i.e., indirect enemy release; Fig. 1C)? (a) Exotic plants have higher PACexerted and lower PACreceived than natives. (b) Plants with higher PACreceived have less biomass and more herbivore damage. (c) Plants with more biomass exert higher PACexerted. |
Indirect soil biota–plant–herbivore interactions | 4. Do exotic plants experience stronger interactions with herbivores when growing in soil communities containing specialist soil biota (i.e., soil biota-mediated biotic resistance against established invasions; Fig. 1D)? (a) Exotic plant biomass will increase and native plant biomass decrease in soils containing specialist soil biota (i.e., ‘home’ soil). (b) Community enemy release of exotic plants from herbivores will be reduced in soils containing specialist soil biota (i.e., ‘home’ soils). |
