Response of Elodea nuttallii (Planch.) H. St. John to manual harvesting in the north-east of France

Published source details Di Nino F., Thiébaut G. & Muller S. (2005) Response of Elodea nuttallii (Planch.) H. St. John to manual harvesting in the north-east of France. Hydrobiologia, 551, 147-157.
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Summary

Action: Use cutting/mowing to control problematic plants

A controlled study in 2003 in a stream invaded by Nuttall’s waterweed Elodea nuttallii in northeast France (Di Nino et al. 2005) reported that harvested and unharvested plots supported similar cover of native aquatic macrophytes over one growing season. Statistical significance was not assessed. Immediately before intervention, all plots were dominated by Nuttall’s waterweed (20% cover; 5 g/m² biomass) with no native submerged macrophytes. Over eight months after intervention began, harvested plots typically contained less Nuttall’s waterweed than unharvested plots. This was true in 14 of 16 comparisons of cover (for which harvested: 3–35%; unharvested: 20–90%) and 16 of 16 comparisons of biomass (harvested: <1–180 g/m²; unharvested: 10–822 g/m² biomass). However, harvested plots had greater cover of native aquatic macrophyte taxa in only 6 of 32 comparisons (for which harvested: 2–5%; unharvested: 0–4%). Methods: The study used a 100-m-long section of an upland stream. Nuttall’s waterweed was “harvested” (presumably by cutting, but not clearly reported) from two 15-m-long sections, either once (February) or twice (February and May). A 36-m-long section upstream was left unharvested. Macrophytes were surveyed immediately before intervention (February) and monthly for eight months after (until October). Biomass measurements were of whole dried plants.