Competitive Interactions of Flowering Rush (Butomus umbellatus L.) Cytotypes in Submersed and Emergent Experimental Aquatic Plant Communities

Abstract

The ability to invade communities in a variety of habitats (e.g., along a depth gradient) may facilitate establishment and spread of invasive plants, but how multiple lineages of a species perform under varying conditions is understudied. A series of greenhouse common garden experiments were conducted in which six diploid and four triploid populations of the aquatic invasive plant Butomus umbellatus L. (Butomaceae) were grown in submersed or emergent conditions, in monoculture or in a multispecies community, to compare establishment and productivity of cytotypes under competition. Diploid biomass overall was 12 times higher than triploids in the submersed experiment and three times higher in the emergent experiment. Diploid shoot:root ratio was double that of triploid plants in submersed conditions overall, and double in emergent conditions in monoculture. Relative interaction intensities (RII) indicated that triploid plants were sixteen times more negatively impacted by competition under submersed conditions but diploid plants were twice as impacted under emergent conditions. Recipient communities were similarly negatively impacted by B. umbellatus cytotypes. This study supports the idea that diploid and triploid B. umbellatus plants are equally capable of invading emergent communities, but that diploid plants may be better adapted for invading in submersed habitats. However, consistently lower shoot:root ratios in both monoculture and in communities suggests that triploid plants may be better-adapted competitors in the long term due to increased resource allocation to roots. This represents the first examination into the role of cytotype and habitat on competitive interactions of B. umbellatus.

Probing the Response of the Amphibious Plant Butomus umbellatus to Nutrient Enrichment and Shading by Integrating Eco-Physiological With Metabolomic Analyses

“…Thereby, it can be used as a model to study the land-water ecotone changes in these ecosystems. The species has two types with different ploidities (diploid and triploid), and there have been numerous studies focusing on their differences in reproduction ( Fernando and Cass, 1997 ; Bhardwaj and Eckert, 2001 ), ecology (i.e., Harms, 2020 ), growth ( Hroudová et al, 1996 ), and on factors related to water level fluctuations. B. umbellatus morphological traits, mainly its well-developed rhizomes and the basal meristem, permit its survival in eutrophic sites ( Baattrup-Pedersen et al, 2015 ), allowing regrowth after weed cutting.…”