From plant traits to invasion success: Impacts of the alienFallopia japonica(Houtt.) Ronse Decraene on two native grassland species

Abstract

Alien invasive plants threaten biodiversity, productivity and ecosystem functioning throughout the world. We examined the effect of Fallopia japonica on two native grassland species (Trifolium repens, Lolium perenne). We hypothesized that its negative effects on the native species are dependent on three mechanisms: (i) allelochemicals released and accumulated in soil with a history of invasion, (ii) altered soil biota and (iii) direct resource competition. We measured the response of the native species as the difference in their functional traits when grown under the three conditions. Our results demonstrate that neither allelochemicals nor soil biota from soil with history of F. japonica invasion had measurable effects on either species. Competition with the invader strongly reduced height, biomass and specific leaf area (SLA) of T. repens, while it had a lower effect on L. perenne. Furthermore, our results reveal that F. japonica took advantage of a positive plantsoil and plant-plant interaction. The results show that the prominent mechanism underpinning the invasion success of F. japonica in the grassland was the direct resource competition. This prominent role is also confirmed by the significant interactions between competition, allelochemicals and soil biota from soils with history of invasion of F. japonica on SLA of the native species.

Fallopia japonica and Fallopia × bohemica extracts cause ultrastructural and biochemical changes in root tips of radish seedlings

“…Co-cultivation of F. Â bohemica and several forbs (Geranium robertianum, Lamium maculatum, Silene dioica, and Symphytum officinalis) in the same soil for 4 months resulted in a 57% reduction in their aboveground biomass (Murrell et al, 2011). A similar effect was observed when F. japonica and white clover (Trifolium repens) were grown in the same soil for 12 weeks, resulting in 20% lower plant heights and 68% smaller aboveground biomass (Mincheva et al, 2016). Inhibition of root growth up to 33% was reported for radish (Raphanus sativus) seedlings after the 14-daysexposure to Fallopia secondary compounds, resveratrol, (À)-epicatechin and emodin (Tucker, 2016).…”

Alien Invasive Plant Effect on Soil Fauna Is Habitat Dependent

“…As hypothesized, this increase in litter following knotweed invasion was more significant in meadow habitats compared to forest habitats. The litter of knotweeds generally decomposes 3-4 times slower than litter of native species ( [36], measurements in meadows) and is commonly of lower quality than the litter of the displaced plant species, thus potentially altering the nutrient cycling of the invaded ecosystems [37][38][39]. Most of the soil variables we measured responded to the knotweed invasion; for example, nitrate available for plants strongly increased in the invaded sites in meadow habitats and C:N ratio was highest in invaded forest habitats.…”

Invasive Alien Plant Species—Raising Awareness of a Threat to Biodiversity and Ecological Connectivity (EC) in the Adriatic-Ionian Region

“…According to Mincheva et al [35], Japanese knotweed has been well distributed in grasslands in the Piedmont region of northwestern Italy during the last 30 years. Populations have also been observed in the western Italian Alps [36].…”