Vegetative regeneration of invasive Ludwigia cytotypes from clonal bud banks across resource gradients: colonizing diploid outperforms polyploid

Authors: Grewell, Brenda; DRENOVSKY, REBECCA - John Carroll University; Futrell, Caryn; IANNUCCI, MARIA - John Carroll University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/6/2017
Publication Date: 2/20/2018
Citation: Grewell, B.J., Drenovsky, R.E., Futrell, C.J., Iannucci, M. 2018. Vegetative regeneration of invasive Ludwigia cytotypes from clonal bud banks across resource gradients: colonizing diploid outperforms polyploid. Meeting Abstract. International Symposium on Aquatic Plants proceedings.

Interpretive Summary: Understanding functional traits that underlie the colonization of invasive plants is key to developing sustainable management strategies to curtail invasions at the establishment phase. Although common, recruitment of clonal plant species from bud banks is often overlooked but may be a key transition phase for successful invasive plant management. Spreading rapidly by hydrochorous dispersal of asexual shoot or rhizome fragments, emergent Ludwigia species from a polyploid complex are among the world’s worst invasive aquatic plants. Aquatic mesocosm experiments were conducted to compare trait responses of stolon and rhizome fragments differing in ploidy (diploid, decaploid) and subjected to contrasting soil nutrient availability (low, high). In this establishment stage of growth, the expectation that decaploid L. hexapetala would produce more biomass than diploid L. peploides ssp. montevidensis from either stolon or rhizome fragments was not supported. Both cytotypes were most responsive to nutrient availability when sprouted from rhizomes. Polyploid rhizomes had twice the nonstructural carbohydrate reserves than diploid congeners at the start of the experiment, yet the diploids were more efficient in utilizing stored reserves for biomass production. Diploid rhizomes produced much higher total biomass with increased nutrient availability than polyploid plants from either fragment type, irrespective of nutrient availability. However, the primary shoot length of the polyploid exceeded that of the diploid under high nutrient availability, suggesting greater spatial foraging potential. Our experiments suggest the diploid species has a superior ability to maximize resource uptake, use and allocation across contrasting resource gradients in the early, colonizing phase of growth. Management strategies should prioritize rapid response to newly colonizing diploid invaders, and reductions in nutrient loads to aquatic environments may be more effective toward controlling establishment of the diploid congener than the decaploid.

Technical Abstract: Understanding functional traits that underlie the colonization of invasive plants is key to developing sustainable management strategies to curtail invasions at the establishment phase. Although common, recruitment of clonal plant species from bud banks is often overlooked but may be a key transition phase for successful invasive plant management. Spreading rapidly by hydrochorous dispersal of asexual shoot or rhizome fragments, emergent Ludwigia species from a polyploid complex are among the world’s worst invasive aquatic plants. Aquatic mesocosm experiments were conducted to compare trait responses of stolon and rhizome fragments differing in ploidy (diploid, decaploid) and subjected to contrasting soil nutrient availability (low, high). In this establishment stage of growth, the expectation that decaploid L. hexapetala would produce more biomass than diploid L. peploides ssp. montevidensis from either stolon or rhizome fragments was not supported. Both cytotypes were most responsive to nutrient availability when sprouted from rhizomes. Polyploid rhizomes had twice the nonstructural carbohydrate reserves than diploid congeners at the start of the experiment, yet the diploids were more efficient in utilizing stored reserves for biomass production. Diploid rhizomes produced much higher total biomass with increased nutrient availability than polyploid plants from either fragment type, irrespective of nutrient availability. However, the primary shoot length of the polyploid exceeded that of the diploid under high nutrient availability, suggesting greater spatial foraging potential. Our experiments suggest the diploid species has a superior ability to maximize resource uptake, use and allocation across contrasting resource gradients in the early, colonizing phase of growth. Management strategies should prioritize rapid response to newly colonizing diploid invaders, and reductions in nutrient loads to aquatic environments may be more effective toward controlling establishment of the diploid congener than the decaploid.