Competition between young exotic invasive and native dominant plant species: implications for invasions within riparian areas

Abstract

Questions The high competitiveness of exotic invasive species has often been demonstrated, but usually with respect to native species known to have low competitive ability. Considering five exotic and five native riparian species with close characteristics regarding competitive ability, habitat and growth form, we addressed the following questions: (i) do the selected invasive plants produce more biomass than the selected native dominants under competitive pressure; and (ii) are the selected invasive species better competitors than the selected native dominants? Location Common garden experiment at the Henri Gaussen Botanical Garden, Toulouse, France. Methods We selected five native dominant species and five exotic invasive species co‐occurring along a riparian successional gradient of the middle Garonne River (SW France). Young plants of each species were planted in pots in ten intra‐ and 17 inter‐specific combinations in conditions of high water and nutrient availability. To simulate the effects of hydrological disturbance during earlier growth stages, a partial cutting of plants was applied 6 weeks after planting. We measured above‐ground and below‐ground biomass of individuals of each species after 6 mo of growth. Results There were large disparities among species performances, regardless of whether the species were exotic or native. The exotic species produced more above‐ground and below‐ground biomass than the natives species for 73% of the selected species pairs. The exotic species had higher competitive ability than the native species, mainly related to the high competitive effect of I. glandulifera. The two species with the highest biomass production and competitive ability were invasive exotics, whereas the two species with the lowest were dominant natives. Conclusions Our results predict that competition among young individuals could play a major role for the invasion success of the studied exotic species in European riparian areas.

Resource competition in plant invasions: emerging patterns and research needs

“…For some invasive species, intraspecific competition is often the predominant type of competition (Lowe et al, 2003; Vasquez et al, 2008; Young and Mangold, 2008; Blank, 2010; Mangla et al, 2011b; Skálová et al, 2013), likely reflecting stronger differences in competitive ability between invasive and native species than among individuals of the same species. For instance, examination of inter- and intraspecific competition among four native and invasive Impatiens species, Skálová et al (2013) found that the invasive I. parviflora competed better in intra- vs. interspecific competition, while the invasive I. glandulifera performed better under interspecific competition with its congeners, although it may form a large aboveground biomass even in intraspecific competition experiments (Bottollier-Curtet et al, 2013). …”

Differential short-term response of functional groups to a change in forest management in a temperate forest

“…In this study we found only invasive alien forb species, such as Erigeron annuus and Conyza canadensis, in the plots with 100% logging intensity. In the earliest stages of succession, invasive alien species can be very competitive and can outcompete other plant species (Bottollier-Curtet et al, 2013). In monocultures, an indirect consequence of the spread of alien species can be a decrease in insect pollinators and predator species richness and abundance (De Groot et al, 2007;Moroń et al, 2009).…”

Floods affect the abundance of invasive Impatiens glandulifera and its spread from river corridors

“…Its invasion of riparian habitats in the region studied was very fast, and it only took 100 years to colonize the majority of the big rivers in the Czech Republic (Py sek & Prach, 1995a, b;Rydlo, 1999). This is associated with this species' tolerance of a wide range of environmental conditions (Beerling & Perrins, 1993), including relatively low soil moisture ( Cuda et al, 2014) and shading (Andrews et al, 2009;Sk alov a et al, 2012Sk alov a et al, , 2013, and is supported by it being highly competitive (Bottollier-Curtet et al, 2013;Sk alov a et al, 2013;Gruntman et al, 2014). This is associated with this species' tolerance of a wide range of environmental conditions (Beerling & Perrins, 1993), including relatively low soil moisture ( Cuda et al, 2014) and shading (Andrews et al, 2009;Sk alov a et al, 2012Sk alov a et al, , 2013, and is supported by it being highly competitive (Bottollier-Curtet et al, 2013;Sk alov a et al, 2013;Gruntman et al, 2014).…”

“…Its abundance along these rivers has increased with residence time (Mal ıkov a & Prach, 2010) and the largest populations are still confined to river corridors, but there are many reports of it spreading into adjacent habitats (Hejda, 2004;Mal ıkov a & Prach, 2010;Pahl et al, 2013;Kostrakiewicz-Gierałt & Zaja z c, 2014). This is associated with this species' tolerance of a wide range of environmental conditions (Beerling & Perrins, 1993), including relatively low soil moisture ( Cuda et al, 2014) and shading (Andrews et al, 2009;Sk alov a et al, 2012Sk alov a et al, , 2013, and is supported by it being highly competitive (Bottollier-Curtet et al, 2013;Sk alov a et al, 2013;Gruntman et al, 2014).…”