Abstract Detail



Ecology

Drenovsky, Rebecca [1], Reicholf, Rebecca [2], Futrell, Caryn J. [3], Grewell, Brenda [3].

Functional trait responses of invasive Ludwigia species to contrasting hydrologic conditions.

Water regime is a major determinant of plant species occurrence and growth in wetlands.  Extreme weather events, climatic flood and drought cycles, and anthropogenic management of water levels for water supply and recreational purposes subject aquatic macrophyte populations to a broad range of hydrologic regimes during their life cycles. Plant responses to these hydrological stressors may be influenced by ploidy level, as polyploids are predicted to be more stress tolerant than diploids.  In riverine wetlands of California, two emergent floating-leaved Ludwigia cytotypes (L. peploides, diploid; L. hexapetala, decaploid) have become increasingly invasive.  We studied two cytotypes of Ludwigia established from apical shoot fragments in outdoor mesocosms under different inundation treatments (deep-flooded, shallow-flooded, gradual drawdown) and measured functional trait responses.  Based on field observations, we predicted that the decaploid would be more tolerant of drying soils, and that both taxa would experience the greatest growth under shallow inundation.  In contrast to previous studies, the decaploid sustained higher relative growth rates under all treatment conditions, but produced less biomass overall.  However, the decaploid maintained longer shoot growth under all conditions, suggesting greater foraging potential for limiting resources and greater potential for shoot fragmentation supporting vegetative reproduction.  Under progressive soil water deficit, having less biomass to support combined with a higher RGR and shoot length could help the decaploid find soil moisture more rapidly than the diploid.  In contrast, by rapidly transitioning to reproductive life stages in all treatments, alternating wet and dry soil in drawdown zones may ultimately favor seed bank recruitment and diploid persistence.


1 - Biology Department, 1 John Carroll Blvd, University Heights, OH, 44118, United States
2 - John Carroll University, Biology, 1 John Carroll Blvd, University Heights, OH, 44118, USA
3 - USDA-ARS Exotic and Invasive Weeds Research Unit, Department of Plant Sciences, One Shields Avenue, Davis, CA, 95616, USA

Keywords:
none specified

Presentation Type: Poster
Number: PEC012
Abstract ID:299
Candidate for Awards:None


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