Ecosystems Growth & Development

Resprouting potential of rhizome fragments in an invasive aquatic plant

Non-native aquatic Ludwigia species from a polyploid complex are among the world’s most problematic invasive plants. A new paper in AoBP finds out why.

Invasive plant species rely on biological traits that allow them to tolerate stress and utilise limited resources. These traits allow them to occupy niches that native species are generally unable to survive in. Clonality is a plant trait that often is linked to invasiveness, particularly in aquatic ecosystems. Aquatic Ludwigia species are among the world’s most problematic invasive plants. These emergent, clonal species respond to disturbance through fragmentation of shoots and rhizomes, spreading rapidly with water currents. While asexual recruitment of aquatic species from shoot fragments is widely recognized, regeneration from below-ground bud banks is often overlooked.

Exposed rhizomes of Ludwigia hexapetala with bank erosion from high winter flows along the Russian River, California. Image credit: Grewell et al.

In a newly published Editor’s Choice article in AoBP, Grewell et al. compared trait responses of Ludwigia species differing in ploidy (diploid, decaploid) in response to soil nutrient availability when sprouted from rhizome fragments. Superior growth ability was expected for the polyploid; however, the diploid congener outperformed the decaploid under nutrient enrichment. Comparing these results to previous studies with Ludwigia shoot fragments, rhizome fragments appear to have a much greater growth potential. These results will help to inform future management of this invasive species in aquatic ecosystems, specifically that disturbance to below ground structures should be minimised to prevent fragmentation of rhizomes. The authors also suggest that management strategies should prioritise rapid response to newly colonising invaders and reducing nutrient loads in these aquatic environments.