Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Competitive interaction between the invasive Solidago canadensis and native Kummerowia striata in lead contaminated soil.

Abstract

Higher tolerance to stressful environments may result in exotic plants being more competitive than native ones, thus promoting plant invasion. We conducted a greenhouse experiment to test this hypothesis by using invasive Solidago canadensis and native Kummerowia striata as model plant species under lead contamination. Lead was applied as Pb(AC)2.3H2O in solution at three levels (0, 300 mg kg-1 and 600 mg kg-1 soil) to simulate control and two pollution sites on which S. canadensis was found. Invasive Solidago canadensis, native Kummerowia striata, and their combination were grown under each Pb treatment. Under monoculture no differences of biomass, nitrogen (N) or phosphorus (P) contents in S. canadensis were found among treatments, but the growth of native K. striata was significantly depressed at higher soil Pb concentration. When both species were mixed, elevated soil Pb concentrations significantly increased shoot biomass ratio of S. canadensis to K. striata, implying that Pb enhanced the competition of S. canadensis over K. striata. Compared to monoculture, biomass and N and P contents of S. canadensis significantly increased under mixture with K. striata in each Pb treatment. Under both monoculture and mixed culture, Pb concentrations in shoots, roots, and rhizomes of S. canadensis increased with soil Pb content, but Pb concentrations in both above- and below-ground tissues of S. canadensis were significantly lower in mixture than that in monoculture under each Pb treatment. Both Pb treatments and mixture with native K. striata did not change biomass allocation to shoot, root and rhizome of S. canadensis. Evidence from our experiment supported the hypothesis that higher tolerance to Pb stress enabled the invasive S. canadensis to outperform the native K. striata and may have promoted its rapid invasion in Pb contaminated soil.