Functional trait responses of invasive Ludwigia species to contrasting hydrological conditions

Authors: DRENOVSKY, REBECCA - John Carroll University; REICHOLF, REBECCA - John Carroll University; Futrell, Caryn; GALLEGO-TÉVAR, BLANCA - University Of Seville; Grewell, Brenda

Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2025
Publication Date: 5/14/2025
Citation: Drenovsky, R.E., Reicholf, R., Futrell, C.J., Gallego-Tévar, B., Grewell, B.J. 2025. Functional trait responses of invasive Ludwigia species to contrasting hydrological conditions. American Journal of Botany. 112:5. https://doi.org/10.1002/ajb2.70038.
DOI: https://doi.org/10.1002/ajb2.70038

Interpretive Summary: Aquatic emergent Ludwigia species from a polyploid complex are among the world’s worst invasive aquatic plants. Understanding traits underlying colonization and niche breadth of invasive plants is key to developing sustainable management solutions to curtail invasions at the establishment phase when efforts are typically most effective. Hydrological regime is a major driver of wetland plant species distribution and performance. Macrophyte responses to hydrological variation may be influenced by their ploidy, as polyploid taxa are predicted to have wider niche breadths than diploids. We studied functional trait responses of Ludwigia congeners differing in ploidy (diploid; decaploid) in their invasive naturalized range, and established from shoot fragments under deep-flooded, shallow-flooded, and gradual drawdown hydrological treatments in mesocosms. At invaded field sites, we assessed phenological responses of both taxa to seasonal hydrological changes. Counter to expectations based on ploidy, establishing diploids in outdoor mesocosms expressed more traits related to flood tolerance than the decaploid taxon, including greater total leaf area, photosynthetic rates, and aerenchyma and anthocyanin production. These traits supported the diploid’s high relative growth rate, reproductive and total biomass production under flooded conditions. In contrast, higher shoot elongation rates and a trend for longer shoot internode length expressed by the decaploid taxon supported escape from flood stress. Although the decaploid taxon expressed some traits suggestive of greater drought tolerance, these trends were not significant due to high variability among replicates and did not translate to greater growth or biomass production. In contrast, longer-established plants in the field indicated a reversed pattern for flood escape versus flood tolerance traits; the diploid rapidly shifting to flowering and seed production as soils began to dry, whereas the decaploid flowered regardless of soil moisture availability. Together, these data emphasize the importance of ploidy and life stage in response to environmental stressors.

Technical Abstract: Hydrological regime is a major driver of wetland plant species distribution and performance. Macrophyte responses to hydrological variation may be influenced by their ploidy, as polyploid taxa are predicted to have wider niche breadths than diploids. We studied functional trait responses of Ludwigia congeners differing in ploidy (diploid; decaploid) in their invasive naturalized range, and established from shoot fragments under deep-flooded, shallow-flooded, and gradual drawdown hydrological treatments in mesocosms. At invaded field sites, we assessed phenological responses of both taxa to seasonal hydrological changes. Counter to expectations based on ploidy, establishing diploids in outdoor mesocosms expressed more traits related to flood tolerance than the decaploid taxon, including greater total leaf area, photosynthetic rates, and aerenchyma and anthocyanin production. These traits supported the diploid’s high relative growth rate, reproductive and total biomass production under flooded conditions. In contrast, higher shoot elongation rates and a trend for longer shoot internode length expressed by the decaploid taxon supported escape from flood stress. Although the decaploid taxon expressed some traits suggestive of greater drought tolerance, these trends were not significant due to high variability among replicates and did not translate to greater growth or biomass production. In contrast, longer-established plants in the field indicated a reversed pattern for flood escape versus flood tolerance traits; the diploid rapidly shifting to flowering and seed production as soils began to dry, whereas the decaploid flowered regardless of soil moisture availability. Together, these data emphasize the importance of ploidy and life stage in response to environmental stressors.