Competition between an introduced and an indigenous species: the case of Paspalum paspalodes (Michx) Schribner and Aeluropus littoralis (Gouan) in the Camargue (southern France)

Abstract

Paspalum paspalodes, an introduced grass species, and Aeluropus littoralis, an indigenous species, develop abundantly in seasonally-flooded marshes in the Camargue (Rhône Delta, France). Although they occur together in many multispecies communities, neither species occurs when the other is dominat. The cultivation of cuttings of P. paspalodes and A. littoralis in a replacement series in a combination of five proportions (0/100, 25/75, 50/50, 75/25 and 100/0) and four salinities (0,2 4, and 6 g Cl · 1) gave contrasting results for the two species: (1) strong asymmetrical competition in favour of P. paspalodes at 0 g Cl · 1, (2) no significant effect of salinity on the mean above-ground and underground yields per plant for A. littoralis over the range tested, (3) a major decrease in the mean above-ground and belowground yields per plant for P. paspalodes with increasing salinity, (4) a reversal of the competitive balance between the species with increasing salinity. The cultivation of cuttings at high temperatures in a greenhouse in a combination of the same five proportions at two salinities (0 and 4 g Cl · 1) refuted the hypothesis that the introduced species is better adapted to summer temperatures. Because it is not salt-tolerant, P. paspalodes cannot be considered as a potentially invasive species in the Camargue. Its abundance depends on newly created and artificially maintained habitats.

The influence of water level and salinity on plant assemblages of a seasonally flooded Mediterranean wetland

“…P. distichum, an introduced grass from Asia, was the dominant perennial of the shallow-marsh and the second most abundant species at the site during the study. In its native freshwater Indian wetlands it is reported from a wide MWL range (1-89 cm) (Middleton et al 1991) but is sensitive to salinity; Meslé ard et al (1993) reported a reduction in mean yield at salinities of 3.1 mS/cm and absence at salinities of 6 mS/cm. It is likely that the grassland assemblage water regime meets the hydrological needs of P. distichum while avoiding salinity and represent a salinity 'refuge'.…”

Using limiting similarity to enhance invasion resistance: Theoretical and practical concerns

“…However, its role in early establishment success at the local scale may be limited compared with the effect of differences in fitness (Funk & Wolf, ; Kunstler et al, ). Fitness advantage can arise from greater ability to effectively use resources in a specific range of environmental conditions (Freckleton & Watkinson, ; Keddy & Shipley, ; Mesléard, Ham, Boy, van Wijck, & Grillas, ), resulting in a competitive hierarchy (Fargione et al, ; Herben & Goldberg, ). Competitive hierarchies have been shown to occur within functional groups (Turnbull, Coomes, Hector, & Rees, ; Turnbull et al, ; Wedin & Tilman, ), contrary to the within‐group equivalence predicted by limiting similarity (Hubbell, ).…”

Identification and validation of Aeluropus littoralis reference genes for Quantitative Real-Time PCR Normalization

“…Aeluropus littoralis is a perennial monocot grass with the small haploid genome of 349 Mb (2n = 2X = 14) using the C 4 mechanism for carbon fixation [2] that grows in dry salty areas or marshes [3]. Aeluropus littoralis can survive where the water salinity is periodically high [4] and tolerate up to 1100 mM sodium chloride [5]. Therefore, A. littoralis can serve as valuable genetic resource for understanding the molecular mechanisms of stress-responses in monocots, and can potentially be used for improving tolerance to abiotic stresses in economically important crops [6].…”